The device of the expansion tank of the closed type heating system. Filling a closed heating system

Independent design, selection of components and installation of the heating system is one of the most difficult activities. Most often, they try to initially reduce the complexity of these steps. For this, an open heating system is preferred. Expansion tanks, circuits, pumps - how to correctly determine the optimal parameters for these heat supply components?

Features of arrangement of open heating

The classic open-type heating system for a private house differs from a closed one in terms of pressure. It is equal to atmospheric. Therefore, for the arrangement of this type of heat supply, much fewer components and accurate calculations are required. But this does not mean that an open heating scheme can be drawn up unprofessionally.

To automatically stabilize the pressure of the coolant in the pipes, the system has an open expansion tank for open heating. It is the design of this component that distinguishes the open heat supply scheme from the closed one. The movement of the coolant can be carried out in two ways:

• Due to thermal expansion of hot water. This requires an accelerating riser. According to this scheme, an open heating system with natural circulation is designed;
• Installation of pumping equipment. It allows you to increase the speed of movement of the coolant. A pump in an open heating system is required if the total length of the lines exceeds 25 m.

In addition, it is necessary to reduce the coefficient of friction of water when it passes through pipes. For this, the diameter of the latter must be at least 30 mm. Otherwise, hydraulic resistance will increase, which will reduce natural circulation.

The defining component in the scheme is a boiler for an open heating system. It is important not only to choose the right design and principle of operation of the device, but also to follow all the installation rules.

Despite the fact that the cost of an open heating system with a pump will be significantly lower than that of a similar closed system, installation of the first one is difficult. This must be taken into account when designing heat supply.

Selecting an open heating scheme

At the first design stage, it is important to choose the right scheme for an open heating system with a pump. It depends on the parameters of the house, the required thermal mode of heat supply and financial capabilities.

Consider the main parameters that will directly affect the choice and further calculation of an open heating system:

• Total area of ​​heated premises. If this characteristic is less than 60 m², a gravity system can be installed;
• Floors of the house and ceiling height. For a gravitational system, a prerequisite is the presence of an accelerating flow. Without it, air may appear in the open heating system and circulation will deteriorate;
• Estimated thermal mode of operation. For low-temperature, an open heating system with a circulation pump is used. Otherwise, a slight expansion of the water will not create the necessary circulation.

Only after a thorough analysis of these indicators, as well as the calculation of heat losses in the house, can you decide whether to install open-type heating with or without a pump.

It is best to calculate the heat loss of a building using specialized programs. Their demo versions are distributed free of charge.

Gravity heating system

The main difference between gravity and the rest is the complete absence of any mechanisms for the forced movement of fluid through pipes. Those. This process is carried out only due to the thermal expansion of hot water.

For the correct operation of the heat supply, an accelerating riser is installed without fail. It is mounted directly after the boiler and is located vertically. Its height must be at least 3.5 m. If this condition is not met, then the heated liquid coming from the boiler for an open heating system will not have sufficient speed.

In addition to this factor, it is necessary to take into account the following specifics of the organization of an open heating system with natural circulation:

• Mandatory pipe slope. The supply line from the riser should be inclined towards the heaters. Return - to the boiler. Tilt level - 1 cm per meter;
• The boiler is located at the lowest point of the circuit;
• For normal operation, open-type expansion tanks are needed for heating systems. They are also mounted for circuits with forced circulation.

It is not recommended to install an electric boiler for an open gravity-type heating system. Just like the gas counterpart. This is due to the high probability of air pockets, which can lead to overheating of the heat exchanger.

To increase the efficiency of work in an open heating circuit with natural circulation, the diameter of the accelerating riser pipe should be 1 size smaller than the cross section of the main line.

Forced circulation in heating

Recently, owners of private houses and summer cottages have been modernizing the heating system by installing just one component - a pump. It is designed to improve the circulation of the coolant.

In general, the arrangement of an open heating system with a circulation pump is no different from that described above. It is important to choose the right location for the pump. It is mounted on the return pipe in front of its entrance to the heating boiler. The optimal distance should be 1.5 m.

For this open heating scheme, the following points must be considered:

• The pump is installed on the bypass. This is necessary to ensure the circulation of water in the event of a breakdown or power outage;
• Be sure to install a check valve. It will prevent the reverse circulation effect;
• During installation, the direction of movement of the coolant is taken into account.

The advantage of using an open type heating circuit with a pump is to reduce the inertia of the system. Due to the increase in circulation, the batteries and radiators will heat up faster.

For an open heating circuit with a circulation pump, its parameters should be calculated - pressure and performance.

Complete set of open heating system

In addition to the pump in an open heating system, other components should be selected. The performance and efficiency of the entire heat supply scheme will depend on the correct choice.

For the correct calculation of an open heating system, its rated power is first calculated. If the thermal insulation of the building is good, you can take the ratio that 1 kW of thermal energy is required per 10 m² of area. For a more accurate calculation, it is recommended to use special programs. With their help, you can draw up a correct scheme of open heat supply, calculate the optimal characteristics of its components.

For a minimum configuration of the heating system, you will need the following elements:

• Boiler;
• Expansion tank;
• pipelines;
• Radiators and batteries.

The requirements for the last two are low. Most often, polymer pipes are used for arranging heat supply. But experts recommend using a steel pipe for an accelerating riser. This is due to the high temperature in this part of the open-type heating system for a private house.

Almost all models of polymer pipes are designed for temperature effects not higher than + 90 °. This should be taken into account when configuring the system.

Boiler selection for open heating

First of all, it must be warned that the installation of gas and electric boilers for an open heating system is prohibited. Often, air jams form in the system, which will negatively affect the operation of the equipment and can lead to emergency situations. Therefore, solid fuel models or diesel fuel boilers remain the only alternative.

The installation of the boiler must be carried out in accordance with all requirements. It is located in a separate room where fuel cannot be stored. The boiler room must have forced air circulation. To optimize the operation of the equipment, the installation of sandwich chimneys is recommended.

In addition to these factors, there are specific requirements for the normal adaptation of the boiler of an open heating system:

• Do not install long-burning boilers. They are designed for low-temperature operation of the system. In this case, the expansion of the coolant will not be enough for circulation;
• If a pumping group is not installed in the system, a separate installation of a check valve is required;
• The boiler in an open-type heating system for a private house should be located at the lowest point in the circuit.

If the equipment does not include a temperature sensor, it should be installed separately. For measurement accuracy, it is mounted on the supply pipe directly after the boiler.

To remove air in an open heating system, installing an air vent will not solve the problem. It works only if the pressure in the system exceeds atmospheric pressure.

Expansion tank models for open system

To compensate for the thermal expansion of the coolant and timely control of its level, it is necessary to install an expansion tank for open heating. It is located at the highest point of the system and can perform several functions at once.

First, the optimal volume of an open-type expansion tank for heating systems is calculated. It should be at least 5% of the amount of coolant in the system. The standard design has 3 nozzles that perform the following functions:

• inlet pipe. With its help, the expansion tank is connected to an open heating system. Usually its diameter is 1 size smaller than that of the accelerating riser to which installation is performed. Therefore, an adapter is needed;
• circulation pipe. Through it, hot water flows further along the highway;
• signal pipe. Necessary for notification of a critical decrease in the coolant level. When the tap is opened, no water comes out of it - the system should be supplemented.

Additionally, an expansion tank for open heating can be upgraded. In some cases, it can perform the function of a make-up node. This requires an additional pipe, which is connected to the water supply. With a critical decrease in the volume of hot water, you can quickly supplement the system by opening the shut-off valves.

There are several schemes for mounting an expansion tank. For open-type heat supply with a pump, it can be mounted on a distant riser. This option is rarely used, since the efficiency of such a scheme is extremely low. Most often, the expansion tank is installed on the near riser for timely monitoring of the heating status.

Filling the heating system is not as simple as it might seem at first glance. Some users drive air through pipes for a long time, do not heat up at cold radiators, and complain about improper installation, although in fact the issue is in the wrong filling.
How and what to fill in radiators and underfloor heating, more on this later, but first a few words about proper installation.

System design for hassle-free pouring

If there is no gravity flow in the drain of the system, i.e. the drain cock is not the lowest point, then it will be possible to drain the system completely only by blowing air from the compressor. Such a scheme is now being used more and more, as more and more houses are being made, and it becomes difficult or not possible to set a gravity drain.

With this option of draining, the pouring tap can also play the role of a creamy one. It is installed on the return line in front of the cleaning filter at the boiler, if possible at the lowest point of the pipes, in order to drain the maximum by gravity.

Auto fill not allowed

To fill such a tap, they usually put on a rubber hose, which is connected to the plumbing system, or to the pump if a special liquid is poured.
It is impossible to make a permanent connection of this tap to the water supply - you can forget to close it, it can leak. It is unacceptable to equip and automatic make-up from the water supply when the pressure in the system drops. All this threatens with siltation, failure of components with a constant exchange of water, which users will not notice.

To bleed air, the system is provided

All radiators are supplied with Mayevsky cranes for air bleeding. Also, air valves, preferably manual rather than automatic, should be installed on all U-shaped non-typical pipe elevations, if any. For example, when bypassing a door or near a high-mounted indirect heating boiler.

An automatic air vent is always present in automated boilers and this is sufficient for the system. With a non-automated boiler, a safety group is used, installed at the highest point of the pipes (supply at the outlet of the boiler) and equipped with such a device.

What water to fill in the system

The system needs to be filled with ordinary tap water, it will work satisfactorily on it all the time. When designing the elements, they were calculated for the usual aggressiveness of water. Pour boiled, distilled water, or additional additives - create problems and waste money.

Plain water is the best coolant for the system. Filling anti-freeze based on toxic glycols is an exceptionally necessary measure when the system is often left unattended in the off state in winter.

Using an anti-freeze

Antifreezes for home heating systems based on propylene glycol or ethylene glycol have several major drawbacks.

• Both substances belong to the same hazard group - poisons.
• They have less heat capacity, less heat transfer - the speed of movement through the pipes should be greater, in large houses this feature is taken into account in the project.
• They foam, it is more difficult to get rid of airing.
• They are expensive.
• They must be changed after a specified period and no later, and again spend money.
• It is unacceptable to drain them into the sewer - you need to take them out for recycling for money.

Ethylene seems to be more preferable than propylene - it is 2 times cheaper, it foams less. But it is more poisonous, but with normal careful use this is not a critical drawback - both the first and second types belong to harmful substances.

Ways to fill the radiator system

Filling from a water pipe using a rubber hose worn on tap fittings is the simplest. It is enough to open the tap and fill the radiator with coolant to a pressure of 2 atm. Usually in water pipes the pressure is the same or a little more.

If a special liquid is poured from containers, you will have to use a pump. Usually they invite specialists who have submersible electric pumps. A manual water pump can also be used.

There are times when there is no electricity or pressurized water supply, and there is no pump. Then you can fill the system with a long hose and a large funnel. Climbing up to the attic, the roof, creating a height difference of 5 meters, you can create a pressure of 0.5 atm at which the system will work. But one should always strive to create an optimal pressure of 1.5 - 2.0 atm, for better operation of automatic air vents.

Air bleed during pouring

Before filling, expansion tanks must be filled with air at a pressure of 1.5 - 1.7 atm.

With any filling method, water must displace air from the system, which must have a free outlet. At the top point, the air valve opens and the main part of the air exits through it.

After reaching the working pressure, it is necessary to bleed air from all radiators and other points where there are Mayevsky taps. Then top up the system again to the nominal pressure.

Bringing the system to working condition after pouring

In radiators, in pipes, after pouring, it is possible to find small air bags at height differences. They will be gradually eliminated in the process of fluid movement.

There is a lot of dissolved air in the coolant itself, which will collect into bubbles, accumulate in the highest places (at the air vents), and create foam.

Therefore, after pouring, the system is allowed to work, to reach the nominal temperature. During the warm-up process, manual bleeding of air is repeatedly done through all Mayevsky taps, and the system is topped up to the nominal pressure.

Cold radiators remain, what to do

It is not uncommon for the last radiators in dead-end branches to remain cold after filling and test run. At the same time, the coolant comes out of the tap. This means that there are air pockets in the pipes.

The problem can be solved if the branches parallel to this radiator are blocked, more often it is enough to close the radiators adjacent to it at a dead end with taps. Then the pump will be able to push through these plugs and the air will go to the automatic air vent in the boiler or to other taps.

When there is a lot of foam, the pump makes noise after filling

There is so much dissolved air in the coolant that even water, due to pressure drops, foams on the pump impeller. This can be heard from the characteristic noise emitted by the pump - it works in air bubbles.

To eliminate it, it is enough to stop the pump, wait 15-30 minutes, during which time the air accumulates in large bubbles, goes to the outlet points.

Antifreeze foams easily and noise and abnormal pumping can be a headache. To eliminate it, first you need to think again “why they poured ethylene glycol”, then wait for hours, and bleed, bleed the air on the taps.

Filling the warm floor

If it is better to supply the coolant to the radiator system from the return line (they do it) to displace air upwards, then to the underfloor heating collector - only from the supply, in the direction of the liquid in working condition. Otherwise, the control valves may not let through ... At the supply, a tap opens and the coolant enters the distribution manifold.

Before that, all valves on the pipelines are closed, then one valve is opened and its circuit is filled until the coolant exits at the drain valve of the collector (from which it is desirable to organize the hose into a bucket).

So all the contours are filled in turn, after which the warm floor is considered flooded.

Airing the loop can be eliminated by punching, with the closure of parallel branches, but this state of affairs is a mistake in creation - height difference, etc.

The working volume of the coolant in the heating network may decrease due to a number of reasons - leakage, evaporation, steam discharge through an automatic valve, repair work. In an open type scheme, the main riser is emptied and filled with air from the expansion tank, closed - the pressure is significantly reduced. In any case, it is necessary to recharge the heating system, which can be done in several ways.

Signs of a critical shortage of coolant

Not all owners of private houses monitor the technical condition of water heating, it works - and all right. When a latent leak forms, the system continues to function for some time until the amount of coolant drops to a critical level. This moment is tracked by the following signs:

1. In an open system, the expansion tank is first emptied, then the main riser rising from the boiler is filled with air. Result: cold batteries when the supply pipe overheats, turning on the maximum speed of the circulation pump does not help.
2. The lack of water during gravity distribution manifests itself in a similar way, in addition, the gurgling of water in the riser is heard.
3. On the gas heater (open circuit), there are frequent starts / burner starts - clocking, the TT boiler overheats and boils.
4. The lack of coolant is reflected on the pressure gauge - the pressure gradually decreases. Wall models of gas boilers automatically stop when they fall below the threshold of 0.8 bar.
5. Floor-standing non-volatile units and solid fuel boilers continue to properly heat the remaining water in a closed system until the volume released by the coolant is filled with air. The circulation will stop, overheating will occur, the safety valve will work.

An important clarification. When boiling a TT-boiler operating in an open gravitational system, no explosion will follow, since the coolant communicates with the atmosphere. The water heated by the heater will evaporate, then a fire will start in the boiler room. Although the described process takes a lot of time, such situations are far from uncommon.

We won’t explain why the system needs to be recharged - this is an obvious measure to maintain the heating performance. It remains to choose a method of replenishing the heating system.

Choice of refueling option

To replenish the coolant supply, several methods are used:

1. Manual make-up is the cheapest and most versatile option, suitable for all types of wiring.
2. Automatic replenishment from the water supply is practiced only in pressurized systems.
3. To fill a closed network with non-freezing coolant, a manual pressure test pump is also used. An automated circuit device with an electric pumping station connected to an antifreeze tank is practiced in industrial boiler houses.

At home, antifreeze is pumped into the heating network using a pressure pump

Note. If the radiator network and underfloor heating are filled with antifreeze, a simple make-up is done with a small hand pump. But most often filtered tap water is used in the heating system, why - because of the price of non-freezing coolants (especially harmless propylene glycol).

The principle of operation of the automatic make-up unit is based on the operation of a pressure reducing valve that reacts to a decrease in pressure in the heating system. When it falls below the set value, the valve mechanism opens and starts the water from the line. A pumping station operates in a similar way, pumping antifreeze from a separate tank.

Unit with a gearbox (left) and a station pumping coolant from the tank (right)

1. The node consists of 2-3 inexpensive elements and will never turn on without the knowledge of the homeowner.
2. No matter how reliably and efficiently the heating network is installed, there is a possibility of leakage and valve operation.
3. Situation: pipe break, prolonged outflow of coolant in the absence of owners. A completely autonomous "smart" make-up will flood the whole house, ruin the flooring and costly repairs.
4. Imagine an identical situation in an apartment building - a leak from an individual system and the inclusion of automated replenishment will flood the neighbors from below.
5. The smallest sand will accumulate under the valve seat and the element will lose its tightness over time. Under pressure from the water supply side of 4-7 bar, spontaneous replenishment will begin. The most harmless scenario is the discharge of excess coolant through the fuse on the boiler safety group.

Than to eliminate the consequences of the described troubles, it is better to allocate a fraction of time for personal control over your heating. Having found signs of a loss of coolant, you yourself will make a decision - to feed the system immediately, look for a leak or make repairs. For a negative example of using such automation, see the video of our expert:

Manual make-up scheme

The simplest option for filling the system is implemented in 90% of double-circuit wall-mounted boilers, where a cold water supply pipe is a priori connected. A manual valve is installed inside the housing, connecting this line with the heating return line. Often, a boiler feed valve is found on solid fuel heat generators with and without a water circuit (for example, heating units of the Czech brand Viadrus).

Reference. On some models of gas heaters equipped with a DHW heat exchanger (in particular, Beretta), manufacturers instead of a manual tap put an automatic make-up valve with an electromagnetic drive. If the coolant pressure drops below 0.8 bar, the boiler itself draws water to the required level.

In wall-mounted double-circuit heat generators, the make-up valve is located below, where pipelines are connected

To assemble a classic make-up unit suitable for any type of system, you will need the following parts:

• a tee with a side outlet DN 15-20, corresponding to the material of the heating pipe, - a fitting for metal-plastic, polypropylene, and so on;
• poppet (spring);
• ball valve;
• couplings, fittings.

The task of the check valve is to prevent water from the heating network from returning to the water supply. If we are talking about pumping antifreeze with a pump, you can’t do without a valve at all. The fittings are installed exactly in the order of enumeration:

1. The tee cuts into the heating return after the circulation pump.
2. A check valve is connected to the branch pipe of the tee.
3. Next comes the ball valve.

Advice. If there is no fine filter at the inlet of the water supply to a private house, it is advisable to provide one on the feed line. The element will protect the heating system from the ingress of fine sand and rust particles accumulating on the check valve plate and in the seats of three-way valves.

The principle of operation of the unit is simple: when the tap is opened, water from the centralized line enters the heating pipelines, since its pressure is higher (4-8 Bar versus 0.8-2 Bar). The filling process of a closed system is monitored by the pressure gauge of the boiler or the safety group. If you accidentally overpressure, use the Mayevsky tap on the nearest radiator and bleed off excess water.

To control the amount of coolant in the expansion tank of an open heating network located in the attic of the house, the tank must be equipped with 2 additional pipes with a diameter of ½ inch:

Comment. If you are interested in calculating the minimum volume of the expansion tank, follow the link.

The circuit with a non-return valve and a stopcock is also applicable for filling solar systems (solar collectors) and geothermal circuits of heat pumps with antifreeze. How to use the make-up boiler valve is described in the video:

Automatic make-up unit

If you are firmly confident in the reliability and build quality of the system, you can mount an automated circuit that adds water from the cold water pipe. What to buy:

• pressure reducing valve (easier - reducer);
• 3 ball valves;
• 2 tees;
• pipe for the bypass device.

An important point. The water entering the gearbox must be pre-cleaned with a coarse mesh filter, otherwise the valve will quickly become clogged. If such a filter is not provided at the entrance to the building, install it in front of the make-up unit.

In this scheme, the pressure gauge shows the pressure on the side of the heating network, the bypass and taps are needed to service the make-up module

The main actuating element of the circuit - the gearbox - consists of the following parts:

• fine filter at the inlet pipe;
• spring seated valve with rubber seals;
• pressure regulator handle with printed scale, range - 0.5 ... 4 bar (or higher);
• manual shut-off valve;
• outlet check valve.

Note. There are more expensive models of make-up gearboxes with a built-in pressure gauge that measures the pressure on the side of the heating system. Since this device is already in the security group or boiler, it makes no sense to spend extra money and duplicate it. An exception is when the make-up is embedded far away from the heat source (read the next section).

As you can see, the reduction machine already contains all the necessary elements - a filter, a check valve and a regulator. It remains to assemble a simple circuit with a bypass and service valves designed to remove and service the gearbox.

It is easy to control the valve - use the regulator to set the minimum pressure threshold in the heating system, open the valves of the direct line, and close the bypass. How to properly adjust the automatic valve is shown in a short video:

Advice. If you plan to put a coarse filter in front of the gearbox, provide an additional service tap in order to clean the mesh without turning off the water in the whole house.

To organize the automatic addition of antifreeze to the system, you can adapt a "hydrofor" - a water station with an electric pump designed for water supply from a well. The pressure switch of the unit must be reconfigured for a minimum pressure of 0.8 bar, a maximum pressure of 1.2 ... 1.5 bar, and direct the suction pipe to a barrel with non-freezing coolant.

The feasibility of this approach is highly questionable.

1. If the "hydrofor" works and begins to pump up antifreeze, you still have to look for and fix the cause of the problem.
2. With a long absence of the owners, make-up will also not save the situation in the event of an accident, since the size of the tank is limited. The pumping station will extend the heating operation for some time, but then the boiler will turn off.
3. Putting a large barrel is dangerous - you can flood half the house with toxic ethylene glycol. Non-toxic propylene glycol is too expensive, as is spill cleanup.

Examples of organizing automatic refueling from containers of different capacities

Conclusion. Instead of additional pumps and automatic gearboxes, it is better to purchase an electronic unit of the Ksital type. After a relatively inexpensive installation, you will be able to control the operation of the heating through a cell phone or computer and quickly respond to emergencies.

How to connect to the heating system

With a closed circuit, there is not much difference where to connect the make-up pipeline - to the supply or return. We recommend using the classic proven method - the tie-in point should be located on the return line next to the boiler, after the circulation pump and expansion tank. Causes:

• the node is located in the furnace room, next to the equipment and appliances;
• pumping water into the return is immediately reflected on the pressure gauge installed on the supply behind the boiler;
• the tie-in is located at the lowest point, the flow is distributed in 2 directions - into the boiler and radiators, the air is squeezed out evenly.

Classic tie-in scheme of the make-up module

The piping of solid fuel units involves the installation of a condensate protection circuit with a three-way valve. It is impossible to make make-up in front of this valve - it will immediately close from cold water and the boiler pressure gauge will begin to lag with readings. Crash inside the circuit, between the 3-way valve and the heat source.

In the same way, make-up cuts into the return line of an open system. The second option is to add coolant directly to the tank, the disadvantage of the method is to lay the supply pipe to the attic.

The right connection is shown on the left - inside the primary boiler circuit

The make-up line connection is also allowed at other points:

• to a separate fitting of a solid fuel boiler, provided by the manufacturer;
• to the bottom of the hydraulic gun;
• to the return manifold of the distribution manifold;
• to the outlet of the indirect heating boiler.

These options are usually implemented in complex and branched systems of country cottages. Connecting the make-up to the boiler is demonstrated in the next video:

Finally, about the safe addition of coolant

When filling water or partial make-up, follow our recommendations:

1. When the system is hot, replenish slowly by opening the valve a quarter of the lever travel. In this way, it will be possible to avoid the formation of air pockets and protect the boiler heat exchanger from temperature shock.
2. Refuel from scratch when the heat generator is not running and the circulation pump is switched off.
3. Check the pressure in the expansion tank and go through all the radiators, opening the Mayevsky taps for.
4. If your boiler is equipped with modern electronics, be sure to read the instructions regarding make-up. Often it is necessary to activate a special service mode in the unit.
5. Excess pressure is easily released through the nearest air vent.

Complex system make-up module can be connected to the low loss header and manifold

Reference. Cast iron heat exchangers easily crack from sudden temperature changes, and steel fireboxes are covered from the inside with condensate. The latter mixes with soot and forms a dense coating.

Pumping antifreeze with a hand pump is not fraught with pitfalls. Crimping plants are equipped with their own pressure gauge, which allows you to control the actual pressure at the tie-in point.

Even a minor repair of one of the radiators or a heating pipe is inevitably associated with a complete drain of the coolant from the heating system. After completion of work, the circuit will have to be filled with water. The question arises - how to start the heating correctly? What temperature should the water be, at what speed should the liquid be poured? How to prepare and flush the home heating network? It is better if the work is done by the masters - many factors will have to be taken into account.

Types of heating systems in private houses

Residents of apartment buildings do not have to start the heating system on their own. Before starting repairs, specialists will warn all neighbors about the work and drain the liquid from the whole riser. The filling will also be handled by services that serve communications.

In a private house, heating can be installed in accordance with one of 2 standard schemes:

1. open.

1. closed.

An open network, which is also called a gravity network, is built without the installation of circulation pumps that distill the coolant inside the network. The circulation of the liquid is carried out due to natural processes: hot water rises, where in the expansion tank installed at the top point, the carrier contacts the air. The cooled water descends to the lower part of the circuit, to the boiler, and is supplied for heating.

Open systems are rarely mounted. You can meet the "classics" only in houses where old boilers, metal pipes and cast-iron radiators are used for heating. The volume of coolant in these types of heating networks is large, respectively, the energy consumption is not economical.

Closed circuits are heating with the connection of pumping equipment, which ensures constant circulation of hot water inside the system. Energy consumption (gas or electricity) is minimal, because the volume of liquid is only a few tens of liters. Due to the constant movement of water, the boiler is turned on only to heat the coolant to a predetermined temperature.

Replacing the coolant: reasons and frequency

Replacing water in a closed and open heating circuit is carried out:

• During the first start of heating.

• After seasonal drying.

• When starting after repair work.

Regular topping up of liquid is required during operation, if there was no drain after the heating season.

Why drain water from a home system

The question to which there is no definite answer is whether it is necessary to drain the circuit annually after the end of the heating season? The decision depends on the type, age and material of manufacture of the main elements - pipes and radiators, as well as on the total volume of liquid.

Most often, systems with old cast-iron radiators are drained for the summer. The reason is the appearance of a leak after turning off the boilers. Old cast iron fins are screwed together with old gaskets. When there is hot water inside the batteries, the seals expand to provide a stable seal at the seams.

After the water cools, the material from which the gaskets are made naturally shrinks, and at the junction of the ribs, a leak begins. But a long downtime of old radiators without water is fraught with accelerated corrosion, rust inside the radiator and old pipes crumbles in a dry environment, and can disable the entire riser.

In closed new circuits, filling the heating system is not a costly process. But it is not recommended to completely drain the liquid every year - this is not necessary.

The frequency of replacing and topping up fluid in the heating system

How often do you need to change the fluid in the heating system? A few general rules:

• In open-type circuits of private houses, it is enough to simply add water if the system is tight, without exposing old communications to stress checks in the form of long dry downtime. Replacement is necessary only in case of emergency repair or preventive sealing, after flushing.

• Closed heating systems need preventive flushing and change of coolant after a few years.

The frequency of filling with new fluid depends on the characteristics of the water, the life of the synthetic coolant, and the general condition of the system. With strong airing of the extreme points, it is recommended to identify the cause - find the place of the leak and check the tightness of the heating network. Typically, water changes are carried out every few seasons.

The choice of coolant: what to fill in the home system

Before pouring new fluid into a closed-type heating system, it is imperative to select a coolant. Only 3 options:

1. Water.

1. Distilled water.

1. Synthetic carrier.

Important! Water can be used in any home heating system, as long as part of the circuit does not come into contact with cold outside air. If the boiler room is outside the house, the pipes are laid in the ground without thermal insulation, it is necessary to use non-freezing liquids - when the boiler is turned off, frozen water will lead to cracking of the pipes.

Can the system be filled with tap water

Do not try to save money by pouring tap water into the new system. Tap water is “enriched” not only with chlorine, which, when heated, adversely affects the surfaces it comes into contact with. Under the influence of temperature, which can reach 60 - 80 °, plaque begins to form on the inner walls of pipes, connectors, radiators. The deposits resemble scale inside an electric kettle with the same consequences: hard deposits eventually block the internal gaps. As a result, some of the radiators can remain cold even at high media temperatures.

In addition to troubles with water stone, which forms a layer of plaque on the walls of pipes, the use of ordinary tap water can cause problems due to chemical reactions that occur in the media when heated. Aggressive impurities do not have the best effect on the condition of the coating inside radiators, corrode seals, and accelerate corrosion processes.

Conclusion - with a small amount of liquid, it makes no sense to save. It is better to pour distilled water into a closed-type heating system.

Advantages:

• Low cost.

• Reduced viscosity, good fluidity.

• No impurities.

• No chlorine.

• Increased boiling point.

Distillate as a coolant has a beneficial effect on the operation of the entire system: purified water warms up faster, the load on pumping equipment is reduced, there is no risk of clogging inside pipes, deposits on the inner walls.

Synthetic coolants: application features

On sale there are ready-made solutions and concentrates based on:

• propylene glycol.

• Ethylene glycol.

• Glycerin.

Despite the imperfect performance of ethylene glycol, it is better not to pour solutions based on it into the home heating network - the substance is dangerous to health.

When buying, you should focus not on the price, but on the degree of concentration of the active substance. Different brands of coolant are diluted in a certain proportion. Before preparing the solution, be sure to read the instructions for diluting the composition.

Synthetic carriers degrade over time, so before throwing away the canister from the concentrate, find information on the expiration date and mark with a marker near the boiler or inlet pipe so that you do not forget to replace the coolant in time.

Replacing the coolant in a standard closed home heating network

The launch of the heating system in a private house with filling with water is carried out using a complex technology. To work, you will have to buy or borrow special equipment and follow the instructions. If you are not sure of the integrity of the circuit, there are visible damage to the elements, be sure to call a specialist.

Preparatory stage: what is required for work

Before filling the heating system in a private house, determine the method of pouring liquid into the circuit. There are 4 options for resolving the issue:

1. Networks equipped with valve automation are filled without third-party intervention. The principle is that when the pressure level inside the circuit drops, the valve automatically opens and filling takes place until the optimum operating pressure is reached.

1. Heating with a modern double-circuit boiler is filled from a water pipe: the systems are connected.

1. A circuit with an expansion membrane tank is easier to fill through the pipes where the expander is located, after dismantling the tank.

1. With the help of a special supercharger - a pump for pumping water into the heating system, which is connected to the inlet pipe.

From the tools you will need keys of the appropriate diameter for dismantling the tank, a pump if you plan to fill the distillate, a sealing tape for connections.
If the question is being resolved how to start heating in a private house after downtime, or if it is necessary to replace the old carrier, you will have to purchase a special flushing agent.

Leak test: how to make a pressure test

The old network must be checked for tightness and no leaks. Also, a mandatory check is carried out at the first start-up of heating. Do not neglect the crimping stage, especially if the house has areas with floor heating that will be under the screed and decorative coating. Fixing a leak after the repair is completed is expensive and not easy.

Before starting the test of the old heating, all the water is drained. To drain the carrier, open the tap. You need to act slowly and carefully. Before draining, be sure to check the temperature of the water - the media must cool to 30 o. The drain valve is located at the lowest point of the circuit.

Important! Use a measuring container when draining the coolant to find out the exact volume of liquid. There will be no question about the amount of water that needs to be poured into the heating network.

After drying, the air valve is opened - the Mayevsky tap. Air will fill the circuit and equalize the pressure within the system.

Start pressing. Using a pump: connect a hose to the inlet pipe. The valve at the top is left open so that air can escape freely.

The fluid is injected until a pressure exceeding the working indicator by 1.5 times is reached. That is, if the operating pressure is 1.5 bar, when checking, it is necessary to increase the indicator to 2.0 - 2.25 bar (but not more than the maximum indicator allowed for the boiler).

Close the top valve after water begins to flow from it. Assess tightness. Check the dryness of all difficult areas:

• Places of entry and exit of pipes from radiators.

• Pipe connections.

• Points at the inlet and outlet of the boiler.

• Other threaded connections.

The liquid under high pressure is left for several hours: if during this time there is no leak, then the heating is in order.

There are two ways to create excessive pressure: liquid (water injection) and dry (air injection). The difficulty of self-checking lies in the fact that when pouring water, an unpleasant situation can arise if there is a gap in the circuit (crack or leaky connection). It is better to entrust the crimping to the master.

Do you plan to leave water as a heat carrier? Simply drain the excess until the pressure drops to an operating value of 1.5 bar.

Flushing your home heating system

Cleaning must be done:

• If the system is old.

• If ordinary water was used as a coolant.

Before washing, dilute the cleaning agent with water in the proportion indicated in the instructions. Pour the product with a pump, fill the circuit with water.

Leave for several hours. During this time, the solution dissolves the sediment accumulated in the radiators, removes deposits from the inner walls.

After flushing, drain all the liquid and proceed to fill the system. Also, flushing is mandatory before filling a closed-type heating system with antifreeze.

Filling with coolant: step by step

Before starting to fill the liquid, measure the required amount of coolant. If synthetic solutions are used, prepare the mixture by diluting the concentrate with distillate to the desired volume.
Before connecting the pump for pumping coolant into the heating system:

• Close the drain cock.

• Check the air bleed valves: all taps must be closed.

• Mayevsky's crane, located at the top point, is left open.

A pump is connected to the pipe through which the liquid will be poured. Typically, pumps are equipped with flexible hoses with threaded connections. The water intake hose is lowered into the container with the carrier.

Start filling the system. It is important to choose the optimal power of the pump, avoiding too fast filling. Simultaneously with the set of water, monitor the open tap. Filling is stopped after the carrier begins to flow out of the open Mayevsky tap.

Checking and preparing for launch

The last step before starting the heating is to remove excess air and check. It is necessary to bleed the air remaining in the circuit from all air valves. To do this, alternately open the taps at the extreme points, release air. The taps are closed after the water starts to flow.

When all the air is bled, check the pressure indicator. Normally, the indicators of all pressure gauges installed in the circuit should match, and be at around 1.5 - 1.8 bar. When using antifreeze, the indicator is sometimes increased to a maximum of 2 bar.

After checking the pressure, turn on the boiler. At a carrier temperature not exceeding 40 °, the system operates up to 1 hour. Then the heating is turned off. After cooling, another check is performed at a higher temperature. The carrier is heated to 60 - 70 o. In this mode, heating is left for 2 - 3 hours.

Starting an open heating system

Filling an open heating system is easier. No special tools needed. It is enough to determine the upper point of finding water in the expansion tank. You will need an assistant who will monitor the air taps.

Work rules

The liquid is drained through the drain pipe located at the lowest point. If necessary, the circuit is flushed. Filling the system is performed in the following sequence:

• Shut off the drain valve.

• Open the air bleed valves.

• Distillate is slowly poured into the expansion tank.

Continue to fill the system with short breaks so that the air rises evenly to the surface. Filling is carried out until the moment when liquid begins to flow from the air taps. The valves are closed.

Add water to the expansion tank up to the mark. You can not fill the expander completely. When heated, the volume of liquid increases, and water over the edges of the tank will begin to pour out. The maximum coolant level is 2/3 of the internal volume of the tank.

System check and maintenance

After completion of work, air is bled from the radiators. Check each valve one by one. Add the required amount of water to the tank.

When operating an open system, it must be remembered that the warm carrier is constantly in contact with air, and, accordingly, evaporates. Therefore, periodically it is worth looking into the expansion tank. When the level drops, simply top up with enough water.

Before checking, be sure to turn off the boiler and wait until the water has cooled to room temperature. Do not add media to hot water. Use liquid with a temperature up to 40 o.

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Main characteristics

Closed-type heating systems have their own characteristics:

1. The coolant is hermetically sealed and does not come into contact with air.
2. To maintain pressure inside the system, special expansion tanks are used that support this indicator.
3. The coolant practically does not evaporate, which does not require its constant renewal.

Such systems also require the presence of a circulation pump, which mixes the liquid in the pipes.

There are several options for filling a closed heating system with liquid:

• For filling, you will need a pump that will supply water directly from a well or other source. We connect the discharge hose of the device to the drain pipe, on which you must first open the shut-off valve. It should be said that when performing such work, it is necessary to open all the shut-off and Mayevsky valves (for air outlet) to allow water to enter any point of the system.
• Expansion tanks in such mechanisms are mainly mounted to the pipe with a thread, which makes it very easy to remove them. Thus, you will have access to the pipe. Using this hole, you can pour water into this system. Very often, expansion tanks are installed at the highest point, which makes the procedure even more convenient. When water is visible from the pipe, you can finish filling and mount the expansion tank in place.

To create pressure in the system after that, you can remove the nipple, which is located at the top of the tank, and pump it to the required level with a conventional pump.

It is very important to constantly monitor the pressure gauge so as not to exceed the pressure level in the system and not provoke an accident. As you can see, pumping water into such structures is relatively simple, but it is very important to follow the sequence.

How to pour the coolant into the heating system with your own hands, see the video:

stroybud.com

How to distinguish a closed heating system from an open one

The process of filling heating with water largely depends on its design:

• Open. This system uses the natural circulation of the coolant (usually water), when there is no additional pressure. The basis of its work is the elementary laws of thermodynamics: the liquid circulates here slowly, because an additional pump is not used. At the highest point of the open circuit, a special expansion tank is mounted to compensate for the increase in water volume when heated. This container takes in excess water during expansion, returning it back in a cooled state. The tank is not airtight, so the liquid constantly evaporates from it: its volume has to be replenished from time to time. The boiler in an open system, as opposed to the tank, should be mounted at the very bottom of the diagram.

• Closed. A completely sealed system in which the heated coolant moves under the influence of a circulation pump. Closed-type heating is also equipped with an expansion tank, however, unlike an open system, it is completely sealed here and can be installed anywhere in the system, and not just from above. Inside the container there are two compartments separated by a rubber membrane. The lower part of the expansion tank is filled with liquid, and the upper part is filled with air: due to its pressure on the membrane, a comfortable pressure level (1.5 atm.) is maintained in the circuit. When the temperature of the coolant rises, it penetrates through the valve into the expansion tank and compresses the air. After cooling, the liquid is pushed back into the circuit by compressed gas.

The list of situations when there is a need to fill the heating system with water:

1. On first start. As already mentioned, this procedure is usually carried out by those plumbers who were involved in the installation of the heating system.

1. Repair. The preliminary discharge of the coolant is accompanied by repair measures when it is necessary to repair or replace the shut-off valves, radiator, pipeline section, etc.

1. After seasonal reset. Systems with cast-iron radiators are tried to be emptied after the end of the heating season, as this reduces the wear of intersectional paronite gaskets by an order of magnitude. In addition, in some cases, the coolant can also be drained for the winter: this usually happens in country houses that are not used in winter.

1. Reducing the quality of the coolant. The fluid inside the system is constantly exposed to critical influences, either heating up or cooling down. This provokes precipitation (if water is used) in the form of lime and rust. For synthetic coolants, such an operating mode is fraught with the fact that the viscosity level changes. You should also take into account the fact that in metal circuits, the liquid gradually accumulates iron impurities in itself. All this leads to a decrease in the efficiency of heating and its operational resource, up to the failure of individual elements. Therefore, there are certain recommendations on the frequency of replacement of the coolant, depending on the situation. For example, it is recommended to change distilled water in a system with a double-circuit boiler once a year, before the start of a new heating season.

Preparation

Regardless of whether a new, just installed system is being launched, or the circuit was reset to repair or replace the coolant, the engineering network must undergo certain preparation before filling:

• Drain. Before pouring a new coolant into the system, the old one must be completely drained. To do this, turn off the boiler and wait for the water temperature to drop to room temperature. Further, by opening the drain valve at the bottom of the heating circuit, all the liquid is drained: it must be collected in special containers for subsequent disposal. After waiting for the system to be completely empty, open the Mayevsky valve at its upper point - this will allow the pressure in the pipes to stabilize.

• Flushing. It is necessary in order to remove all debris from inside the circuit - chips, scale, limescale, etc. This is done using a pump connected to the network, which pumps the flushing solution inside. It often takes several cycles until the water comes out completely clean. The water for the last wash is enriched with neutralizers to remove additives in the first portions.

• Pressing. It allows you to test before pouring the coolant how tight all the joints and connections of the system are. For this, excess pressure is created inside the circuit by forcing air or using a coolant. To carry out the test, you will need a mechanical (electric) pump. There is also an option to connect the water supply, but this kind of procedure is much more difficult. Before switching the pump to the inlet pipe of the system, all joints and connecting nodes must be carefully inspected. If no defects were found, excess pressure is created inside the circuit (it is necessary to exceed the norm by 1.5 times).

• Elimination of leaks. All leaks found during pressing must be eliminated. If the flaw is at the junction, then it is repacked by installing a new seal. Leaks in the middle of the pipe are solved by replacing the damaged section.

• Checking the set. A closed heating system must be checked for the presence of the necessary protective equipment before filling with water. First of all, we are talking about Mayevsky cranes, bypasses, thermometers and pressure gauges. If any of these elements is missing, it will most likely cause problems in the heating operation.

Calculation of the volume of coolant

In cases where water is used as a coolant not from the pipeline, it is important to know exactly how much liquid is needed.

You can determine this in the following ways:

1. When resetting the system, measure the drained liquid using a meter or a special container of known volume. The same method can be applied during flushing and pressing the circuit.

1. Separately summarize the volume of the elements included in the system. The parameters of the boiler, batteries and expansion tank are indicated in the passport documentation for these products, and the volume of the pipeline is determined using special tables from the plumbing guide.

Filling a closed heating system

Having prepared the required amount of coolant, you can start filling the pre-washed and tested system. The most convenient way to do this is with a vibration pump.

Given the particular importance of this procedure, accuracy will be required during its implementation:

1. For the last time, all joints are checked for defects and leaks.

1. Shut-off valves are blocked through which the coolant is discharged from the heating circuit. This is done to avoid unnecessary fluid loss.

1. Check if the air valves are working. If it turns out that their level of performance is insufficient, it is recommended to fully open the Mayevsky valve for the duration of the entire filling procedure. You can also leave the valve in the open position in the upper section of the network, which will significantly speed up the release of air accumulated in the pipes.

1. They begin to pour water through the nozzles adjacent to the boiler. In this case, it is desirable to supply the liquid as slowly as possible: in this case, the internal air can be freely discharged through the open fittings. Rushing at this stage usually results in traffic jams. To avoid water hammer, the tap on the pipe through which water is supplied must be opened no more than half.

1. In the course of filling the circuit, all taps and valves from which liquid begins to splash are closed: before starting the process, it is advisable to place an empty basin or bucket near each of them. For this reason, water is harvested with a certain margin, taking into account possible losses.

1. When pouring water, it is recommended to change the position of the pump from time to time, switching to higher outlets. This is especially true for filling a closed system in houses with several floors.

1. Checking the quality of the filling. To fill the amount of coolant, it is recommended to determine not only the total figure, but also the volume of individual sections of the circuit. This will make it possible to control the quality of filling during its implementation using counters on the inlet nozzles. This will allow you to monitor the amount of already pumped coolant, comparing it with the volume of individual elements of the system. If, after filling a certain area, it turns out that it took less liquid than was calculated, then an air lock has formed inside. If the filled volume of the coolant exceeds the calculated data, you need to look for a leak.

1. Release of excess air. Upon completion of the filling procedure of a closed system, it is necessary to remove all air from it. The main pipe is deaerated using an air valve, which is usually on the boiler. If the forced circulation method of the coolant is used in the circuit, then air is bled from the pumping equipment using an air valve, which is usually located in front of the device.

Each radiator must also be freed from air pockets, starting with the heating elements on the ground floor. This procedure is very simple: with the help of a key or a screwdriver, the Mayevsky tap is opened, closing it only after water appears in the hole. In conclusion, you need to check the return line using the valves installed on it. Having released all the air, the pressure in the closed system must be increased to 1.5 atm., And only after that, turn off the water supply.

Feeding the system

To ensure efficient operation of a closed heating circuit, the pressure in it must be kept at a constant level. This is directly affected by the volume of coolant circulating through pipes and batteries. In any case, it will gradually leak out, despite the high level of tightness of the system: to make up for these losses, fluid replenishment will be required. The issue is solved by special make-up valves, which are equipped with sections of the circuit with the lowest pressure (most often - next to the pump, directly in front of it).

Small houses with low power heating systems are usually equipped with mechanical type valves. In such a scheme, compensation for pressure surges occurs due to the rubber membrane of the tank. In order to avoid the occurrence of emergencies, it is necessary to constantly monitor the pressure parameters.

Automatic completion

Double-circuit boilers, as a rule, have a device for automatic filling of the coolant. Install this electronic control unit on the inlet pipe. The convenience of this solution lies in the fully automatic control of the pressure in the system through the timely pumping of fluid.

In the event of a critical underestimation of the pressure in the network, the signal from the pressure gauge is sent to the control unit. He, in turn, activates the supply valve, which begins to let water into the system until the pressure is completely stabilized. However, convenience comes at a price, which is expressed in the high cost of automatic filling devices.

How to pour water into an open heating system

In order to fill the open heating system of a private house with a coolant, a slightly different procedure is used. The main difference from closed networks lies in the internal pressure of the circuit: here it corresponds to atmospheric pressure, which makes it possible to use an expansion tank as the main control device. In open heating systems, it is mounted above all other elements.

Step-by-step instructions for filling an open heating system with water:

1. Draining the old fluid and cleaning the circuit. This is done in the same way as in the case of a closed system.

1. To fill water into an open system, an expansion tank is used, which looks like an open tank. After removing the lid, they begin to pour water: filling a small circuit is usually done with a bucket. Filling large systems in this way is quite tedious, so it is better to use a household vibration pump. This will require a capacious tank with pre-prepared water. The pump is equipped with flexible hoses on clamps: one end is immersed in a container of water, and the other in an expansion tank.

1. It is recommended to supply water slowly so that the air has enough time to escape. When using a vibration pump, it is necessary to ensure that the pressure in the circuit during its filling is within 1.5-2 atm. When it is lowered, more water is added to the preparation tank so that it is possible to immerse the suction hose deeper. The water supply is shut off after it begins to pour into the expansion tank.

1. At the end of the procedure, it is necessary to free the circuit from air pockets. To do this, Mayevsky's taps are opened in turn on all existing radiators, closing them only after the appearance of water. In order not to soak the floor, it is recommended to substitute a portable container under the taps. After releasing the gas from all batteries, top up the water in the tank. As practice shows, the final release of the open system from air occurs through the expander after the first furnace.

During intensive use of open heating (most often in winter), the coolant will gradually evaporate through the expansion tank. This is explained by the high temperature of the coolant. To maintain the performance of the system, it must be periodically topped up, making sure that its temperature does not rise above +80 degrees.

What water is better to fill in the heating system

There are several types of water poured into the heating circuit:

• Water supply. This also includes liquid taken from a well, well or nearby reservoir. The main advantage of this option is its cheapness. However, the quality of such a coolant is rather low: it acts quite aggressively on the inner walls of the circuit due to the salts and oxygen dissolved in it.

• Boiled. Boiling allows you to remove from the water part of the oxygen and salts that precipitate. However, it is quite difficult to prepare water for a volumetric circuit in this way.

• Cleaned with reagents. To neutralize harmful impurities, instead of boiling, it is convenient to use special chemicals - reagents. Water prepared in this way needs to be carefully filtered before being poured into the system.

• Distilled. It is sold in plumbing stores in containers of various sizes. Rainwater also has similar properties, which some owners of private houses specially collect for subsequent use in heating networks.

• Antifreeze. They are used instead of water in cases where the heating system is prone to freezing (the crystallization temperature of antifreeze is much lower than that of water). This method of filling the heating circuit is rarely used because of its high cost.

Conclusion

Filling the heating circuit with water is a rather complicated and time-consuming procedure, which is recommended to be performed by at least two people. During its implementation, it is important not to rush, carefully following all the recommendations. The preparation of water for filling into the circuit deserves special attention: in cases where, for financial or other reasons, liquid from the water supply is used, it must at least be boiled. To remove sediment and rust particles gradually accumulating in the coolant, it is recommended to equip the system with special mud filters.

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How to fill the heating circuit with water

Due to the fluidity and high heat capacity, heat transfer fluids are used to transfer heat from the boiler to consumers, among which water occupies the first place.

It is used to fill even the most capacious heating systems. It is widely available and inexpensive, which determines the widest scope.

Both pumped from natural reservoirs or wells, and tap water has many impurities and mineral inclusions. When boiling, the impurities settle like scale on the walls of the boiler and form growths similar in composition on the pipes. These deposits are extremely harmful to systems with the latest modifications of heating units. Therefore, water must first be purified, boiled, or, if funds allow, purchase distillate.

The second drawback of water is the ability to contain oxygen, which causes corrosion of the metal. Due to the high mineralization, coupled with the oxygen released during heating, it is not recommended to change the water in the heating circuits more than once a year.

Weighty advantages of water as a heat carrier are optimal viscosity and heat capacity. It accumulates and gives off heat better than antifreeze by 15-20%. Inferior to them in terms of fluidity, due to which it does not seep through the seals of the detachable joints of the system, in terms of viscosity, due to which it moves faster through the pipes.

Calculation of the volume of coolant for filling

To correctly fill your own heating system with water, you need to determine it will be required in liters. The volume of the coolant without any problems can be calculated by yourself. To do this, we need to sum up

V syst. heating = V boiler + V expansion tank + V radiator + V pipes

The useful volume of the boiler is usually indicated by the manufacturer in the technical documentation for the equipment he produces. The capacity of sectional radiators too. If such information cannot be found, then there are average indicators:

V of one section of the radiator, depending on the material of the case:

The total volume of the radiator is found by multiplying this figure by the number of sections.

V expansion tank of a closed type before purchase is selected so that its useful volume is equal to or slightly exceeds the volume of water, taking into account thermal expansion. So this parameter must also be known.

For open-type heating systems with an expansion tank that freely communicates with the atmosphere, the volume is taken according to the actual dimensions.

Volume in pipes:

V pipes = 0.786×D 2×L

where D is the inner diameter of the pipes, L is the length of the pipes.

The volume of the system will then be:

V system \u003d V pipes + V boiler + V expansion tank + V consumers.

Where V consumers, this is the sum of the volumes, the boiler and other devices. Their volumes can be found in the technical documentation or calculated. It is tedious to increase the calculated volume by 15-20 percent, i.e. multiplying by 1.15 or 1.20.

A more time-consuming way is to fill the system with tap water and then drain, measuring the volume with a meter or measuring containers.

Sometimes tap water is used, but this greatly reduces the heating time. Saving a ruble, we lose thousands. It is better in this case to pass water through special membrane or chemical cationic filters.

To fill the heating, we also need adapter hoses and a pump for pumping liquid.

The dependence of the pouring technique on the cause

The reasons for filling affect the sequence of work. If this is a new system, then we check it visually and carry out tests, pressure testing by pumping in air or liquid about 2-2.5 atmospheres (the norm is 1.25 part of the working pressure, but not less than 2 atmospheres). We check the absence of pressure drop on the pressure gauge.

To fill small heating circuits, you can take a car pump instead of a compressor. Sometimes pressure testing is carried out directly with liquid using a centrifugal pump, after connecting the expansion tank to the system. For small volumes, a hand pump with a liquid compartment can be used.

If we carry out periodic cleaning of the system with the replacement of water, then it is necessary to first drain the liquid, having prepared a place or container for it. After waiting for the coolant to cool, we release excess pressure by unscrewing the nipple. At the top point, we open the valve or Mayevsky valve to communicate with the atmosphere. At the bottom point, gradually open the drain valve. With a sharp opening, water hammer occurs, leading to damage. Here you need to be careful.

After draining the coolant, we fill the system with flushing liquid and use the pump to circulate it.

Then they are washed with clean water with additives and a neutralizer designed to neutralize the additives of the first wash.
After these operations, as in the first case, heating is pressure tested. Identified leaks and weak points are usually in places of welding and threaded connections.

Cast iron batteries are equipped with connecting gaskets, which dry out over time, coarsen and leak when cooled. They should be replaced and additional tightening of the batteries should be carried out. After the repair work, again crimping and with a positive result, we proceed to the next stage.

Heating is filled with water through the lower point with the top open. Having connected the electric pump, we pump water into the system through the tap. Moreover, the valve is half open or less to prevent water hammer. Gradually, the system fills up, which confirms the noise from the movement of water and a slight gurgling. We finish when water starts to flow from the top point.

Then we begin to bleed air from connected consumer appliances, a boiler, boilers, an expansion tank with a membrane and batteries using the available taps and valves. Next, we connect a transparent hose to the upper point of the system, which we lower into a container with a coolant. Turning on the pump, we additionally fill the heating until water flows out of the transparent hose in the container without air bubbles.

If possible, after that, you can loop the pumping system with a hose and drive the coolant several times. This will provide additional degassing. And finally, air is pumped behind the expander membrane, providing the necessary pressure for the operation of the heating circulation pump, which we turn on for a run without heating.

To fully check the quality of filling the system, it is necessary to turn on the heating and heating on a trial basis, determine the absence of air pockets and the uniformity of heating using a thermal imager or an infrared temperature meter.

At the same time, with the help of taps or modern temperature controllers, the installation and regulation of temperatures in the premises is carried out. The effectiveness of thermal insulation is also evaluated. It is necessary to provide a supply of purified water and a means of adding it to the system in order to eliminate evaporation losses. All these actions are designed to ensure trouble-free operation of heating for the winter period.

Heating make-up rules

Recently, not only in private houses, but also in apartments, they began to arrange individual heating. Usually, double-circuit boilers with a make-up module are installed. And it’s easier to learn how to recharge yourself than to call the master, for this:

• We open the tap at the bottom of the boiler, then at the top of the system the air release valve and when water appears, close it and the feed tap.
• We turn on the boiler and if murmuring and gurgling are heard in the pump, then we remove the outer casing from the boiler and find it.
• We loosen, but do not unscrew the screws with a screwdriver, to bleed air from it until moisture appears. The pump has a cover screwed on for this. Although the instructions say that these boilers have automatic air venting devices, they cannot remove all of it.

Especially at the first start-up of heating, it is necessary to gradually, smoothly heat up the coolant to avoid damage from water hammer. You can not immediately turn on the boiler at full power. When heating is stopped, it is also important to lower the temperature slowly.

This is especially important for extended heating networks, which have significant deformation and thermal expansion. From this expansion or contraction, the retaining fasteners or molds generate stresses that are discharged abruptly, transferring the impact of the liquid.

Fluid, depending on flow sections, can increase the force of impact and produce destruction elsewhere, usually at bends. And if resonance occurs, then the loads increase many times and the pipes even break off the mounts. They begin to "play" and "dance."

With rapid filling with liquids, in pipes, due to air pockets, pressure increases are also formed, which are discharged by water hammers. This is where the recommendation to drain and fill the heating comes from slowly, opening the tap a quarter or half. Resonance phenomena, depending on size, weight, fastenings, deposit thickness and other factors, vary. This imposes additional restrictions. You need to take your time and be careful.

That is why the design of heating networks of enterprises and apartment buildings is done by specialists taking into account many factors. Heating of individual houses is done according to standard projects.

Technological progress and cheaper smart home equipment allows using a smartphone to control and change heating parameters remotely. The main thing is to be in the coverage area of ​​​​cellular communications and the Internet. This further expands the possibilities of using water, because timely measures can be taken to prevent its defrosting.

Other amenities, such as raising the room temperature before arrival and economy mode during departure, are included.

The choice of water for heating is advisable if a backup heating system is provided. If heating in winter is used periodically or there is a possibility of shutdown and defrosting of the equipment, then it is better to use antifreeze liquids. For example, in a dacha with short-term visits characteristic of dacha winter life.

Refueling with non-freezing coolant

Before figuring out how to fill various heating systems with antifreeze liquids or antifreeze, you should understand their varieties.

For normal operation of heating systems, antifreezes (anti - against, freeze - freeze) must be:

1. non-toxic, excluding the possibility of the slightest threat to people;
2. non-flammable, and their vapors are explosion-proof;
3. inert to the materials from which the heating system is made;
4. have a heat capacity not less than its calculated value;
5. be fluid.

In its "pure" form, antifreezes are aggressive, capable of destroying pipelines, boilers and heating appliances. To reduce or completely eliminate the negative properties of non-freezing liquids, they are diluted with water in the proportions indicated by the manufacturer of the compositions.

Additives are also used: anti-corrosion, stabilizing, cleaning, anti-foaming and others. The less water, the lower the freezing point and the higher the cost. When diluting antifreezes, it is usually necessary to add the additives that come with the kit. Additives work at a certain concentration.

Without a complex of additives, the compositions cannot be used, since they provide the specified parameters. For the same reason, it is not recommended to mix different coolants, especially with different bases. Their service life is drastically reduced.
Antifreezes have an increased viscosity, they cannot be used in heating with natural circulation.

The average shelf life of organic coolants is 3-5 years, after which the additives lose their properties and the liquid becomes aggressive. When replacing, the old antifreeze must be pumped out and taken for recycling, which further increases costs.

Once upon a time, cars used water for cooling, but now this is a rarity. Now in the world more than 70 percent of heating systems work on water, but the percentage is decreasing all the time. The reason for the widespread use of antifreezes is both their high cost and increased requirements for equipment, toxicity and the need for their disposal. The spent antifreezes, for more complete removal, are drained in a state heated to 45 degrees.

Now the main equipment is designed for water and manufacturers who value their reputation often indicate that they do not guarantee operation on antifreeze. Or indicate the permitted type of antifreeze under certain conditions. It's dangerous to experiment on your own.

Anti-freeze compositions are critical to overheating. They begin to decompose and form gases, solid deposits. Air locks, burns in boilers and equipment failure are formed. At temperatures of 80 degrees and above, vaporization begins, so modern boilers have heating up to 75 degrees, supported by automation. When exceeded, an emergency shutdown of the boiler occurs. With organic coolants, the temperature is reduced to 70 degrees.

For the safe operation of the heating circuit with antifreeze, automation is needed that turns off the heating unit when the temperature is exceeded. If there is no such device in the heating system circuit, antifreeze should not be used as a coolant.

Usually, the type of coolant is indicated in the technical documentation for boilers and equipment. The use of another coolant removes responsibility from the manufacturer and terminates its warranty service.

For refueling heating systems, coolants based on ethylene glycol, propylene glycol and glycerin are produced.

cheapest ethylene glycol

The disadvantage is toxicity, a dose of 100 - 250 grams is fatal to humans. It has the third hazard class according to GOST. Vapors are also toxic. Permissible MPC norm - 5 milligrams / cu. meter. Therefore, it cannot be used in open heating systems. It is also forbidden for double-circuit boilers, because the product may leak into the hot water supply line.

To exclude this, craftsmen make the water supply pressure higher than heating. But even this does not give a full guarantee and, in case of damage, may cause the boiler to fail. The use of ethylene glycol is only permitted for closed heating systems.

Heating leaks and breaks are very likely. If the system is filled with an inexpensive but toxic ethylene glycol cleaner, leaks can pose a health hazard to homeowners. The relatively low price is the reason for the application. You can't buy health like antifreeze. Therefore, the choice is yours.

Ethylene glycol has 1.5-3 times greater penetrating power and aggressiveness to seals.

Automobile antifreezes, antifreezes, should not be used categorically, as they contain more toxic additives.

For glycol coolants:

1. the maximum temperature should be no more than 70 degrees, which further increases the size of the batteries;
2. viscosity is 40-60% higher and pumping requires 1.5-2 times more motor power and minimization of bends, bends and increased pipe size;
3. volumetric expansion during heating is 140-150% more, it is required by the same amount, an increased volume of the expansion tank;
4. density is 15 - 20% higher, strength characteristics increase.

The construction of a new system designed for the use of synthetic heat carriers, respectively, costs 1.3-1.5 times more expensive than the construction of a water analogue. The considerable cost of the non-freezing liquid itself should not be forgotten either.

Alteration of water is also not used, since the service life is reduced and, as a result, it is more expensive. Glycol mixtures are also aggressive to zinc, causing delamination and sludge that completely clogs pipes. In older structures, galvanized pipes are common.

However, taking into account the above disadvantages, ethylene glycol is still used. It is necessary to fill the systems only after all the equipment of the heating system is adapted for filling with antifreezes.

A special feature is the need to locate the filling equipment on impervious surfaces to prevent glycol from entering the living quarters and carefully control the connections of the adapter hoses. Although this, neat craftsmen, do when refueling with any antifreeze.

The specifics of the use of propylene glycol

Recently, it has been actively replacing other types of heat carriers, although in terms of its physical and technical parameters it almost does not differ from ethylene glycol and requires almost the same change in the equipment of heating systems.
According to GOST, it belongs to the second hazard class and also requires disposal. MPC vapors - 7 milligrams / cu. meter.

The advantages of this non-freezing coolant:

1. relatively environmentally friendly and harmless to humans. This is the main reason why many manufacturers now recommend it for single-circuit and double-circuit boilers;
2. has lubricating properties, which facilitates the operation of pumps;
3. with complete evaporation of water, it does not freeze, while maintaining fluidity;
4. corrosiveness is very low, and with additives it improves even more;
5. If spilled, just rinse with water and wipe.

Polypropylene glycol liquid has disadvantages. This
its cost, which is 1.5 - 2 times higher than ethylene glycol, because it is produced mainly abroad. Fluid is corrosive
to metal pipes, not compatible with pipelines constructed from galvanized pipes, because upon contact with zinc, the additives of the composition lose their properties. At a temperature above the permissible level, decomposition begins with the formation of gases, foam and a solid insoluble precipitate.
Despite all these shortcomings, it is considered one of the best coolants.

Feature of glycerin coolants

As harmless as propylene glycol at acceptable temperatures. They were historically the earliest to be used for these purposes, getting glycerin from fat. The spill is not dangerous. The advantage is the price, which is lower than that of propylene, while remaining higher than ethylene glycol. Therefore, it is used by counterfeiters to dilute polypropylene glycol.

Even some European manufacturers add it to about 10%, so you need to be careful and read the composition. On the other hand, in the European Union, glycerin is not used as the main component of the coolant.

Glycerin has wider temperature limits up to 105 degrees. Hazard class two.

Flaws:

1. when the maximum temperatures are exceeded during decomposition, a poisonous gas with an unpleasant odor is released;
2. when evaporated, it becomes gel-like, burns and decomposition begin, it is necessary to regularly compensate for evaporation by adding distillate;
3. have increased viscosity and require pipes of larger diameter;
4. easily foams, which is partially removed by additives;
5. has a high penetrating ability and requires the use of paronite and teflon gaskets.

It has significant corrosive activity, and has long been rejected by automakers. Due to modern additives, this is reduced and reduced to nothing. Yes, even with proper use.

Glycerin coolants, however, are recommended to a greater extent than ethylene glycol ones for their harmlessness and, with a complex of additives, work satisfactorily in heating networks. The trouble is that in pursuit of money, they produce products without a full range of additives or without them at all. You need to be careful when buying.

A special type can be attributed to heating systems with electrode boilers, in which the coolant is also a heating element. Heating occurs when current flows through the solution during its ionization.

The solution, in addition to the above, should have a calculated electrical resistivity of the order of 3.5 - 4 kΩ cm. For this, an aqueous solution or a solution of propylene glycol with additives is used, which create the necessary electrical characteristics.

Useful video on the topic

The video will visually present the process of filling the heating circuit and setting up the expansion tank:

Common to all coolants is gradualness when starting the system. The temperature must be increased slowly, in steps, not only because of the coolant, but also additives, which also change their properties with temperature. The process of filling systems with both water and antifreeze is similar, but the requirements for the quality of work and safety when filling with antifreeze are increasing. Antifreezes that have expired require disposable containers and removal for disposal.

sovet-ingenera.com

You need to think about how to install an expansion tank in the heating system of a private house in advance, before purchasing it. This makes it easier to determine the location of the tank and the method of laying the pipeline for connection to the heating network. But situations are different, it is impossible to foresee everything in advance. It is worth studying the essence of the issue a little, and you yourself will be able to figure out where to install and how to properly connect the expansion tank, including with your own hands.

The installation location of the tank depends on the type of heating system and the purpose of the tank itself. The question is not what the expansion tank is for, but where it should compensate for the expansion of water. That is, in the heating network of a private house there may be not one such vessel, but several. Here is a list of functions that are assigned to tanks installed in different places:

• compensation of thermal expansion of water in open-type heating systems;
• the same for closed systems;
• serve as an addition to the regular expansion tank of the gas boiler;
• perceive the increasing volume of water in the hot water supply network.

An open tank, where the coolant is in contact with atmospheric air, is the hallmark of an open heating system. In this case, the expansion tank is installed at the highest point in the heating network of a private house. Often such systems are made gravity flow with increased pipeline diameters and a large amount of coolant. The capacity of the tank should be appropriate and be about 10% of the total water volume. Where, if not in the attic, to put such an overall tank.

For reference. In old one-story houses, you can often see small expansion tanks for an open heating system installed in the kitchen next to a floor-standing gas boiler. This is also correct, the container under the ceiling is easier to control. True, it does not look too good in the interior. To put it mildly.

Alternative homemade tanks

Heating systems of a closed type are distinguished by the fact that a membrane expansion tank for water can be placed anywhere. But still, the best installation option is in the boiler room, next to the rest of the equipment. Another place where it is sometimes necessary to install a closed expansion tank for heating is the kitchen in a small house, since the heat source itself is located there.

About additional containers

Following new trends, many manufacturers complete their heat generators with built-in tanks that perceive the volume of coolant that increases when heated. These vessels cannot correspond to all existing heating schemes, sometimes their capacity is not enough. In order for the coolant pressure to be within normal limits during heating, an additional expansion tank for the wall-mounted boiler is installed in accordance with the calculation.

For example, you converted an open gravity system to a closed one without changing the lines. The new heating unit was selected according to the heat load. Whatever the capacity in it, it will not be enough for such an amount of water. Another example is heating with underfloor heating in all rooms of a two- or three-story house plus a radiator network. Here, the volume of coolant will also come out impressive, a small tank will not cope with its increase and the pressure can rise greatly. That's why you need a second expansion tank for the boiler.

Note. The second tank to help the boiler is also a closed membrane tank, located in the furnace room.

When hot water supply at home is provided by an indirect heating boiler, then the question also arises - what to do with the expanding water when heated. One option is to install a relief valve, as is done on electric water heaters. But the indirect heating boiler is much larger in size and through the valve it will lose too much hot water. Where is the best place to choose and install an expansion tank for a boiler.

For reference. In buffer tanks (heat accumulators) of some manufacturers, it is also possible to connect a compensating tank. Moreover, experts recommend putting it even on large-capacity electric boilers, which is shown in the video:

How to put the tank

When installing an open tank in the attic, a number of rules should be observed:

1. The container must stand directly above the boiler and be connected to it by a vertical riser of the supply line.
2. The body of the product must be carefully insulated so as not to waste heat on heating a cold attic.
3. It is imperative to organize an emergency overflow so that in an emergency situation hot water does not flood the ceiling.
4. To simplify level control and make-up, it is recommended to bring 2 additional pipelines into the boiler room, as shown in the tank connection diagram:

Note. The emergency overflow pipe is usually directed to the sewer network. But some homeowners, in order to simplify the task, take it out through the roof straight to the street.

The installation of a membrane-type expansion tank also has its own characteristics. Given the way this product works, it can be placed vertically or horizontally in any position. It is customary to fasten small containers to the wall with a clamp or hang them from a special bracket, large ones - just put them on the floor. There is one point: the performance of a membrane tank does not depend on its orientation in space, which cannot be said about the service life.

A vessel with a closed type will last longer if it is mounted vertically with the air chamber up. The fact is that sooner or later the membrane will exhaust its resource, which will cause cracks to appear in it. The internal arrangement of the tank is such that, when placed horizontally, air from its half will quickly penetrate through the cracks into the coolant, and that one will take its place. We'll have to urgently put a new expansion tank for heating. The same result will quickly appear when the container is hung upside down on the bracket.

In a normal vertical position, air from the upper part will not rush to penetrate through the cracks into the lower part, just as the coolant will reluctantly go up. Until the size and number of cracks increase to a critical level, the heating will work properly. This process sometimes takes a long time, you will not notice the problem immediately. But no matter how you place the vessel, you should adhere to the following recommendations:

1. The product must be placed in the boiler room in such a way that it is convenient to service it. Do not install floor-standing units close to a wall.
2. When wall-mounting the expansion tank of the heating system, do not place it too high, so that when servicing it is not necessary to reach the shut-off valve or air spool.
3. The load from the supply pipelines and shut-off valves should not fall on the tank branch pipe. Fasten the pipes together with the taps separately, this will facilitate the replacement of the tank in case of breakage.
4. It is not allowed to lay the supply pipe on the floor through the passage or hang it at head height.

How to beautifully place the equipment in the boiler room

Connection methods

It is hydraulically correct to connect the device at a point located on the return line in front of the boiler and circulation pump, which allows the latter to work optimally. Although the tank can also be connected to the supply line, then the membrane will last less due to contact with a higher temperature coolant. The second moment: when working on the supply of a solid fuel boiler in an emergency, steam can penetrate into the tank. Air and steam are compressible media, and in this case, the rubber "pear" will no longer compensate for the expansion of water.

The correct connection of the expansion tank to the heating system is always carried out through a shut-off ball valve with an American. Thanks to this, the element can be taken out of service at any time and quickly changed without waiting for the coolant to cool. If you install a tee and a second tap on the connection, as shown in the connection diagram, then the container can be emptied beforehand:

Note. When installing and connecting an expansion tank for a boiler, the same rules should be followed. Only the tank itself should be designed for pressure in the water supply network, and not for heating, which is described in detail and intelligibly in the video of our expert:

How to check and pump up an expansion tank

Before connecting and filling the tank with coolant, it is necessary to check the pressure in the air chamber of the tank for compliance with the pressure in the heating network. To do this, a plastic plug is unscrewed or removed from the side of the air compartment, and under it there is a conventional spool familiar to you from car cameras. You measure the pressure with a pressure gauge and adjust it to fit your system, pumping it up with a pump or lowering it by pressing the spool rod.

For example, the design pressure in the network after filling should be 1.3 bar. Then in the air compartment of the expansion tank it is necessary to make 1 Bar, that is, 0.2 Bar less. The trick is that the rubber "pear" of the tank is pressed from the side of the water. Otherwise, when cooling, the compressed coolant will begin to draw air through automatic air vents, which is unacceptable. After setting, open the tap, fill the entire system with coolant and calmly start the boiler.

Note. Some manufacturers indicate the factory pressure in the air compartment on the packaging of their products. On it, you can choose a suitable tank and not bother with pumping.

Conclusion

All work related to the installation, connection and configuration of the expansion tank is not highly qualified and can be done by hand. Moreover, during operation, it is better for you to be able to do the pressure check yourself. Its decrease or jumps are the first reason why the automatic gas boiler turns off the burner. Therefore, in such cases, the first thing to do is to check the air chamber of the tank with a pressure gauge if there are no serious coolant leaks in other places.

The heating system, being a complex engineering structure, consists of many elements with different functional purposes. An expansion tank for heating is one of the most important parts of the heating system circuit.

When the coolant is heated, the pressure in the boiler and the heating system circuit increases significantly due to the temperature increase in the volume of the heat-carrying liquid. Given that the liquid is a practically incompressible medium, and the heating system is hermetic, this physical phenomenon can lead to the destruction of the boiler or pipelines. The problem could be solved by installing a simple valve that can bleed the excess volume of hot coolant into the external environment, if not for one important factor.

During cooling, the liquid contracts and air enters the place of the discharged coolant into the heating circuit. Air locks are a headache for any heating system, because of them, circulation in the network becomes impossible. Therefore, it is necessary. The constant addition of a new coolant to the system is very expensive, heating cold water is much more expensive than heating the heat-carrying fluid that came to the boiler through the return pipeline.

This problem is solved by installing the so-called expansion tank, which is a tank connected to the system with one pipe. Excessive pressure in the heating expansion tank is compensated by its volume and ensures stable operation of the circuit. Externally, expansion tanks for the heating system, based on the results of the calculation and the type of heating circuit, are different in shape and size. Currently, tanks are produced in various shapes, from classic cylindrical tanks to the so-called "tablets".

Types of heating systems

There are two schemes for the building's heating networks -. An open (gravity-flowing) heating system is used in centralized heating networks and allows you to directly take water for hot water needs, which is impossible in private housing construction. Such a device is located at the top point of the heating system circuit. In addition to leveling pressure drops, the heating expansion tank performs the function of natural air separation from the system, as it has the ability to communicate with the outside atmosphere.

Thus, structurally, such a device is a compensation tank of the heating system that is not under pressure. Sometimes, by mistake, a system with gravitational (natural) circulation of a heat-carrying fluid can be called open, which is fundamentally wrong.

With a more modern closed circuit, an expansion tank of a closed-type heating system with a built-in internal membrane is used.

Sometimes such a device can be called a vacuum expansion tank for heating, which is also true. Such a system provides for the forced circulation of the coolant, while air is removed from the circuit through special taps (valves) installed on the heaters and at the top of the system pipelines.

Device and principle of operation

Structurally, a closed expansion tank in a heating system is a cylindrical tank with a rubber membrane installed inside, which separates the internal volume of the vessel into air and liquid chambers.

The membranes are of the following types:

The gas pressure is adjusted for each system individually, which is described by the instructions attached to such devices as an expansion tank for heating a closed type. Some manufacturers in the design of their expansion tanks provide for the possibility of replacing the membrane. This approach somewhat increases the initial cost of the device, but later, if the membrane is destroyed or damaged, the cost of replacing it will be lower than the price of a new expansion tank.

From a practical point of view, the shape of the membrane does not affect the efficiency of the devices, it should only be noted that a slightly larger volume of heat-carrying liquid can fit into a closed-type balloon expansion tank for heating.

Their principle of operation is also the same - with an increase in water pressure in the network due to expansion when heated, the membrane stretches, compressing the gas on the other side and allowing excess coolant to enter the tank. During cooling and, accordingly, a drop in pressure in the network, the process takes place in the reverse order. Thus, the regulation of constant pressure in the network occurs automatically.

It is necessary to focus on the fact that if you buy an expansion tank of the heating system at random, without the necessary calculation, then it will be very difficult to achieve the stability of the heating network. If the tank is much larger than necessary, the pressure required for the system will not be created. If the tank is smaller than the required size, then it will not be able to accommodate the excess volume of the heat-carrying liquid, which can result in an emergency.

Calculation of expansion tanks

To calculate an expansion tank for closed-type heating, you first need to calculate the total volume of the system, which consists of the volumes of the pipelines of the circuit, the heating boiler and heating devices. The volumes of the boiler and heating radiators are indicated in their passports, and the volume of pipelines is determined by multiplying the internal cross-sectional area of ​​\u200b\u200bthe pipes by their length. If there are pipelines of different diameters in the system, then their volumes should be determined separately, and then added up.

Further, for devices such as an expansion tank for closed-type heating, the calculation is carried out according to the formula V = (Vc x k) / D, where:

Vc is the volume of heat-carrying fluid in the heating system,
k - coefficient. volumetric thermal expansion, taken for water 4%, for 10% ethylene glycol - 4.4%, for 20% ethylene glycol - 4.8%;
D - indicator of the efficiency of the membrane block. Usually it is indicated by the manufacturer or it can be determined by the formula: D \u003d (Rm - Rn) / (Rm +1), where:

Pm - the maximum possible pressure in the heating network, usually it is equal to the maximum working pressure of the safety valve (for private houses it rarely exceeds 2.5 - 3 atm.)
Рн is the pressure of the initial pumping of the air chamber of the expansion tank, taken as 0.5 atm. for every 5 meters of the height of the heating circuit.

In any case, it should be assumed that expansion tanks for heating should provide an increase in the volume of coolant in the network within 10%, that is, with a volume of heat-carrying fluid in the system of 500 liters, the volume together with the tank should be 550 liters. Accordingly, an expansion tank of the heating system with a volume of at least 50 liters is required. This method of determining the volume is very approximate and may result in unnecessary costs for the purchase of a larger expansion tank.

Currently, online calculators for calculating expansion tanks have appeared on the Internet. In the case of using such services for the selection of equipment, it is necessary to carry out calculations on at least three sites in order to determine how correct the algorithm for calculating one or another Internet calculator is.

Manufacturers and prices

At present, the problem of buying an expansion tank for heating lies only in the correct selection of the type and volume of the device, as well as in the financial capabilities of the buyer. There is a wide choice of models of devices of both domestic and foreign manufacturers on the market. However, it should be noted that if the purchase price for such devices as a closed-type expansion tank for heating is much lower than that of the main competitors, then it is better to refuse such an acquisition.

The low cost indicates the unreliability of the manufacturer and the low quality of the materials used in its manufacture. Often these are products from China. As with all other products, the price for a high-quality expansion tank for heating will not have a significant difference of the order of two to three times. Conscientious manufacturers use approximately the same materials and the price difference of models similar in parameters of about 10-15% is determined only by the location of production and the pricing policy of sellers.

Domestic manufacturers have proven themselves well in this market segment. By installing modern technological lines in their production, they have achieved the release of products that are not inferior in their parameters to the best world brands at a lower cost.

It should be borne in mind that it is important not only to buy an expansion tank for closed-type heating, it also requires its correct installation.

Having the necessary skills, subject to the instructions, it is possible to install it yourself. If the master still has any doubts about his knowledge, then it is best to turn to professionals to ensure the stable operation of the heating network and eliminate possible malfunctions.

Let's try to figure out why you need and how to install an expansion tank in the heating system.

We will consider options for an open system with natural circulation and for a closed heating system using a circulation pump. Let's start, however, with definitions.

Our task is to choose a tank that suits us in terms of volume and mount it correctly.

general information

What is an expansion tank and what is it for?

Its very name gives a hint: for an extension. With a fixed mass of the coolant in the heating circuit and pipes, the elasticity of which tends to zero, with a change in the temperature of the coolant, the pressure in the system will inevitably change. Thermal expansion, remember? Water or any other coolant, when heated, expands.

Once the force exceeds the tensile strength of the pipe or radiator... Boom!

The reason for a possible accident is that water, changing its volume when heated, remains practically incompressible. Hence the concept of water hammer: there are no elastic interactions in a liquid medium, to put it simply.

The obvious solution is to create in the system a reservoir with an easily compressible substance - air. With an increase in the volume of water in the presence of such a reservoir, the pressure will increase slightly.

Useful: so that oxygen from the air tank does not contribute to the corrosion of pipes, dissolving in water, in tanks for closed systems it is separated from the water by a rubber membrane.

However, we have described only one of the functions of the expansion tank.

In addition to private houses with fixed volumes and a circuit and a coolant in it, an expansion tank can be found:

• In open systems in contact with atmospheric air;
• In central heating systems with top filling. There, the expansion tank is located in the attic and is connected directly to the supply pipeline of the house heating system.

In both cases described, the installation of an expansion heating tank is needed in order to get rid of air locks. The difference between the two threads in the case of central heating is only about two meters. B is even less.

Clarification: the author can still hear the exclamations of more or less knowledgeable people who, at the height of the heating season, saw a 10 times greater drop in the elevator unit.
Typically 6 kgf / cm2 on the supply pipeline and 4 - on the return (1 atmosphere of overpressure corresponds to a water column of 10 meters).
Do not confuse warm with soft: it is not water from the supply that enters the heating system, but a mixture.
The elevator recirculates the return water in the heating system by injecting a jet of hotter water with a higher pressure from the supply pipeline into it through a nozzle.
As a result, as stated, the difference between the mixture and the return flow does not exceed 2 meters, or 0.2 kgf / cm2.

With such a difference, the water pressure will not be able to squeeze out the air plug from the upper part of the heating system. Hence a simple solution: put some kind of container for collecting air where it will accumulate, and bleed it when the system is started. In the case of an open system, of course, no active actions are needed.

All the air in the system will be pushed up and into the expansion tank. In an open system, it will immediately reunite with the atmosphere. In a closed one, it will wait until the owner of the house opens the air valve.

How and where is the expansion tank placed

So, we are going to design and assemble a heating system with our own hands. If she also earns - our joy will not be the limit. Are there any instructions for installing the expansion tank?

open system

In this case, simple common sense will prompt the answer.

An open heating system is, in essence, one large vessel of complex shape with specific convection currents in it.

The installation of the boiler and heating appliances in it, as well as the installation of pipelines, must ensure two things:

1. Rapid rise of the water heated by the boiler to the upper point of the heating system and its discharge through the heating devices by gravity;
2. The unhindered movement of air bubbles to wherever they rush in any vessel with any liquid. Up.

The conclusions are clear:

1. The installation of a heating expansion tank in an open system is always carried out at its highest point.
   Most often - at the top of the accelerating manifold of a single-pipe system. In the case of top filling houses (although you hardly have to design them) - at the top filling point in the attic.
2. The tank itself for an open system does not need shutoff valves, a rubber membrane, and even a lid (except to protect it from debris).
   This is a simple water tank open on top, into which you can always add a bucket of water to replace the evaporated one.
   The price of such a product is equal to the cost of several welding electrodes and a square meter of steel sheet 3-4 mm thick.

closed system

Here, both the choice of the tank and its installation will have to be taken quite seriously.

Let's collect and systematize the basic information available on thematic resources.

• The installation of the expansion tank of the heating system is optimal in the place where the water flow is closest to laminar, where there is a minimum of turbulence in the heating system.
  The most obvious solution is to place it in a straight dispensing area in front of the circulation pump.
  At the same time, the height relative to the floor or the boiler does not matter: the purpose of the tank is to compensate for thermal expansion and dampen water hammer, and we perfectly bleed air through air valves.

A typical tank setup. Its location in a single-pipe system will be the same - in front of the pump along the water course.

• Tanks in the factory are sometimes supplied with a safety valve that relieves excess pressure.
  However, it is better to play it safe and make sure that your product has it. If not, buy and mount next to the tank.
• Electric and gas boilers with electronic thermostats often come with built-in thermostats. Before you go shopping, make sure you need them.
• The fundamental difference between membrane expansion tanks and those used in open systems is their orientation in space.
  Ideally, the coolant should enter the tank from above. This subtlety of installation is designed to completely remove air from the compartment of the tank that is intended for liquid.
• The minimum volume of the expansion tank for a water heating system is taken approximately equal to 1/10 of the volume of the coolant in the system. More is acceptable. Less is dangerous. The volume of water in the heating system can be roughly calculated based on the heat output of the boiler: as a rule, 15 liters of coolant per kilowatt are taken.
• A pressure gauge mounted next to the expansion tank and the make-up valve (connecting the heating to the water supply) can provide you with an invaluable service. The situation with a stuck spool of the safety valve, alas, is not so rare.
• If the valve releases pressure too often, this is a clear sign that you miscalculated with the volume of the expansion tank. It is not necessary to change it at all. It is enough to purchase another one and connect it in parallel.
• Water has a relatively low coefficient of thermal expansion. If you switch from it to a non-freezing coolant (for example, ethylene glycol), you will again need to increase the volume of the expansion tank or install an additional one.

Conclusion

As usual, you will find additional information on the selection and installation of expansion tanks in systems of different types in the video at the end of the article. Warm winters!

Installing an expansion tank in the heating system ensures its performance and reliability. Devices of this type are used in open and closed systems, with gravity or forced circulation of the coolant.

Expansion tank functions

What is the purpose of the expansion tank? The heating system is filled with a fixed amount of fluid (water or antifreeze) that is prone to thermal expansion. This means that an increase in the temperature of the coolant inevitably leads to an increase in pressure in the system. Since pipes, radiators and other elements of an engineering structure are inelastic, increased pressure will lead to depressurization of the system - a breakthrough will occur at the weakest point.

Water is characterized by low compressibility, so a special device is built into the system - a membrane or open tank. Its function is that when the pressure rises, air will be compressed. This makes it possible to provide protection against water hammer. The installed expansion tank protects the system from excessive pressure increase.

Membrane tanks are designed for a closed-type heating system - they are a container with an elastic waterproof membrane inside, which divides the internal volume into two parts. The membrane is needed so that air does not come into contact with the coolant. Otherwise, airing the network and increasing the risk of corrosion of the steel elements of the system cannot be avoided.

In an open type system, the tank communicates with the atmosphere, due to which air is bled from the pipes. For this reason, the installation location of an open tank is strictly regulated - it must be located at the highest point in the system.

How to connect an expansion tank

How to make a reliable connection of the expansion tank in an open system!? An open-type heating system is characterized by the fact that the movement of the coolant in it is ensured by convection.

The principle of operation is as follows: the coolant heated by the boiler unit is delivered directly to the highest point of the system, as a result of which it enters the heating radiators by gravity and, having cooled down, returns to the boiler through the “return” pipeline. There is always dissolved oxygen in water, which is released during convection, which means that air bubbles tend to rise up.

When considering this diagram, it becomes obvious that the only possible location for the expansion tank is the top point of the system. For a single-pipe system, this is the upper part of the accelerating manifold.

Connection diagram of a membrane tank in an open-type heating system

As a tank, you can use any container of a suitable size made of a heat-resistant material. A cover (not sealed) is needed for it only to protect against debris entering the system. If a small metal barrel was not at hand, the tank is welded from sheet steel 3-4 mm thick.

The tank must be installed in compliance with certain rules, in particular:

• the tank must be placed above the boiler unit and connected by a vertical riser through which heated water is supplied;
• it is recommended to insulate the body of the tank to reduce heat loss, especially if the tank is located in an uninsulated attic at home.

Over time, the water from the tank evaporates and periodically it needs to be topped up. This can be done using an ordinary bucket. If the tank is installed in the attic, which is difficult to reach, a water supply pipe is brought to the tank installation site, and an emergency overflow is organized to avoid flooding the house with hot water in case of an emergency. The emergency overflow pipe is usually connected to the sewer network, but owners of private houses often simplify the task by bringing it outside through a wall or roof.

Expansion tank in a closed heating system

Equipment for the heating system is selected at the stage of its design, taking into account the requirements for the performance of the boiler unit, the length of the pipelines and the volume of the heat carrier involved. A scheme is being developed that indicates the installation locations of all elements of the system, including the expansion tank. In a closed type heating system, a membrane device must be used.

Expander in a closed heating system

When linking a project to an existing boiler house, it is important to take into account the following points:

• The tank should be placed in such a way as to provide normal access for installation and further maintenance. Floor models are not recommended to be installed close to the wall.
• If the unit is mounted on a wall, it is advisable to place it at such a level that you can easily reach the air spool and shut-off valve. Usually the tank is placed under the ceiling of the room, only if it is not possible to mount it at a convenient height.
• The supply pipe must not be placed on the floor across the passage or suspended at human height.
• Pipelines connected to the expansion tank must be fixed to the wall. It is important to avoid a situation where the load from them and from the valves falls on the tank nozzles. Fixing pipes and taps separately makes it easy to replace the expansion device in case of failure.

At the stage of equipment selection, it is necessary to calculate the required volume of the expansion tank. The minimum value of this parameter is 1/10 of the total volume of fluid circulating in the system. It is acceptable to use a larger tank. But an insufficiently capacious tank can become a source of problems, as it is not able to compensate for the increased pressure in the system.

Expansion tank placement rules

For approximate calculations of the volume of coolant in the system, the thermal power of the boiler unit can be taken as a basis. On average, 15 liters of liquid per kilowatt are used. Accurate calculations are made taking into account the length of pipelines, the volume of radiators, etc.

Important! Many models of gas and electric boilers are mini-boiler rooms, that is, they are immediately equipped with a pump for forced circulation of the coolant, as well as an expansion tank. A separate tank does not need to be purchased if the parameters of the built-in membrane tank are sufficient to ensure the functionality and safety of the existing heating system.

When purchasing a membrane expansion tank, pay attention to whether the selected model has a safety valve, due to which excess pressure is automatically released. If this is not provided for by the design of the device, you should buy a safety valve separately and install it in the immediate vicinity of the tank.

Where is the best place to put the tank

The optimal place for mounting a membrane tank is a straight section of the pipeline, which is characterized by a laminar flow of water, that is, the absence or minimum number of turbulences. A good location is the spill area near the circulation pump.

Note! Installation of an expansion tank of a closed-type heating system can be carried out at any convenient height. There is no need to place it at the highest point as it functions solely as a water hammer protector. Unlike an open-type heating system, the air accumulated in the pipeline is vented using special valves - air taps.

From a hydraulic point of view, it is best to install the membrane tank on the return line so that the circulation pump is located between it and the boiler. In this case, the pumping equipment will function optimally.

Scheme of possible placement of the tank

If desired, the tank can also be placed on the supply line, this will not affect the performance of the heating system. But the membrane tank itself will last for a relatively short time, since the polymer membrane will constantly be in contact with the coolant, which has just been heated to 90 degrees, and not with water that has cooled to 45-60 degrees and returned through the pipeline.

Attention! Installing a membrane tank on the supply line is highly discouraged if the boiler is solid fuel. There is a risk that due to an emergency, the water in the boiler will begin to boil and steam will enter the tank. Water vapor, like air, is a compressible medium, due to which the membrane cannot compensate for the thermal expansion of water.

Expansion tank installation process

Now let's figure out how to install an expansion tank in the heating system. There is an important rule for connecting the device: the tank must be connected to the heating system mains using a shut-off ball valve with an American. This principle of installation makes it possible, if necessary, to block the movement of water in the system at any time, remove the faulty membrane tank and install a new one.

Otherwise, it would be necessary to wait for the coolant to cool down and dismantle part of the piping. Ideally, a tee is installed on the liner, as well as a second tap - in this case, before removing the expansion tank, it can be emptied into a substituted container.

Hanging the expander upside down, if the membrane malfunctions, the unit will fail immediately

How to correctly orient the membrane expansion tank in space? The tank is installed with the air chamber up or down, the tank is placed “on its side”. From the point of view of performance, this does not really matter, since in any case the device will perform its functions properly.

However, it is worth considering such a moment: if the air compartment is located below, then the coolant is supplied from above, and the bubbles of air dissolved in it will rise into the pipeline and be removed using an air valve. Otherwise, an air bubble will form in the "water" compartment of the membrane tank over time.

In turn, when the tank is located with the air chamber up, its service life is extended. Over time, from constant contact with hot water, the polymer membrane loses its tightness, cracks appear in it. If the air chamber is located below, then water immediately begins to seep into the air compartment, which will quickly disable the expansion tank, while air will penetrate into the coolant. When the air chamber is located on top, the diffusion of water through the cracks is many times slower, and the device is able to work much longer.

Helpful Hints:

• If you install a pressure gauge next to the expansion tank and the valve, which feeds the heating system from the water supply, it will allow you to control the pressure in the system in order to bleed the excess in time if the safety valve spool is stuck and does not work automatically.
• The frequently repeated release of pressure by the valve indicates that the capacity of the expansion tank has been selected incorrectly. Instead of changing it to a larger tank, it is enough to connect a second tank in parallel.
• Replacing the existing expansion tank with a larger one or connecting a second one will also be required if it is decided to replace the water in the system with antifreeze. This is due to the fact that non-freezing coolants have a higher coefficient of thermal expansion.

If there is no pressure gauge, the expansion tank circuit should be equipped with a safety group

Setting

Before connecting the tank and filling it with coolant, it is required to check the pressure level in the air chamber of the tank - it must correspond to the pressure in the heating system. To do this, remove or unscrew the plastic plug that closes the spool (similar to those installed in car chambers). Using a manometer, it is necessary to measure the pressure and adjust it to the indicators of the heating system. To do this, air is pumped up by the pump or vice versa, it is bled by pressing the spool rod.

Note! The tank should be set in such a way that the pressure in its air chamber is 0.2 bar less than the calculated pressure in the system filled with coolant. If the pear-shaped membrane is not pressed from the water injection side, the coolant, shrinking during cooling, will be able to draw air through.

After completing the settings, open the tap and fill the entire system with coolant. Then the boiler unit is started.

The adjustment step is not required if the factory pressure in the air compartment of the expansion vessel is correct. Manufacturers of some brands of equipment indicate the level of pressure in the tank on the packaging, which makes it possible to choose the option that will be optimal when buying.

Conclusion

You can correctly install the expansion tank, prepare a customizable membrane tank for work yourself, without the help of a specialist. The experience gained can be useful in the future if you need to quickly identify the source of problems associated with a decrease or pressure surges in the system, due to which the burner flame goes out. In such cases, it is recommended first of all to carefully inspect the system for coolant leaks and measure the pressure in the air chamber of the membrane tank.

When planning to create a water heating system in your own home, the owner is faced with a choice of several options. The list of the most important questions includes the type of system (whether it will be open or closed), and what principle the coolant will be transferred through pipes (natural circulation due to the action of gravitational forces, or forced, requiring the installation of a special pump).

Each of the schemes has its own advantages and disadvantages. But still, nowadays, more and more preference is given to a closed system with forced circulation. Such a scheme is more compact, easier and faster to install, and has a number of other operational advantages. One of the main ones is a fully sealed expansion tank for closed-type heating, the installation of which will be discussed in this publication.

But before you purchase an expansion tank and proceed with its installation, you need to at least get a little familiar with its device, the principle of operation, as well as which model will be optimal for a particular heating system.

IN what are the advantages of a closed heating system

Despite the fact that recently a lot of modern devices and systems for space heating have appeared, the principle of heat transfer through a liquid with a high heat capacity circulating through pipes - without a doubt, remains the most widespread. Water is most often used as a carrier of thermal energy, although in some circumstances other liquids with a low freezing point (antifreeze) must be used.

The heat carrier receives heat from the boiler (furnaces with water circuit) and transfers heat to heating devices (radiators, convectors, "warm floor" circuits) installed in the premises in the required quantity.

How to determine the type and number of heating radiators?

Even the most powerful boiler will not be able to create a comfortable atmosphere in the premises if the parameters of the heat exchange points do not correspond to the conditions of a particular room. As it is right - in a special publication of our portal.

But any liquid has common physical properties. First, when heated, it significantly increases in volume. And secondly, unlike gases, this is an incompressible substance, its thermal expansion must be compensated in some way, providing free volume for this. And at the same time, it is necessary to provide that, as it cools and decreases in volume, air does not enter the pipe circuits from the outside, which will create a “plug” that prevents the normal circulation of the coolant.

It is these functions that the expansion tank performs.

Still not so much in private construction, there was no special alternative - an open expansion tank was installed at the highest point of the system, which coped well with the tasks.

1 - heating boiler;

2 - supply riser;

3 - an open expansion tank;

4 - heating radiator;

5 - optional - circulation pump. In this case, a pumping unit with a bypass loop and a valve system is shown. If desired, or if necessary, you can switch forced circulation to natural, and vice versa.

A closed system is completely isolated from the atmosphere. A certain pressure is maintained in it, and the thermal expansion of the liquid is compensated by the installation of a sealed tank of a special design.

The tank in the diagram is shown pos. 6, embedded in the return pipe (pos. 7).

It would seem - why "to fence the garden"? A conventional open expansion tank, if it fully copes with its functions, seems to be a simpler and more inexpensive solution. It probably costs a little, and besides, with certain skills, it is easy to make it yourself - weld it from steel sheets, use an unnecessary metal container, for example, an old can, etc. Moreover, you can find examples of the use of old plastic canisters.

Does it make sense to spend money on a sealed expansion tank? It turns out that there is, since a closed heating system has many advantages:

• Complete tightness absolutely excludes the process of evaporation of the coolant. This opens up the possibility of using, in addition to water, special antifreezes. The measure is more than necessary if the country house in winter is not used constantly, but “arrivals”, occasionally.
• In an open heating system, the expansion tank, as already mentioned, must be mounted at the highest point. Very often, an unheated attic becomes such a place. And this entails additional troubles for the thermal insulation of the container, so that even in the most severe frosts the coolant in it does not freeze.

And in a closed system, an expansion tank can be installed in almost any part of it. The most appropriate place for installation is the return pipe directly in front of the boiler inlet - here the parts of the tank will be less exposed to temperature effects from the heated coolant. But this is by no means a dogma, and it can be mounted in such a way that it does not interfere and does not disharmonize its appearance with the interior of the room, if, say, the system uses a wall-mounted boiler installed in the corridor or in the kitchen.

• In an open expansion tank, the coolant is always in contact with the atmosphere. This leads to a constant saturation of the liquid with dissolved air, which is the reason for the activation of corrosion in the pipes of the circuit and in radiators, to increased gas formation during the heating process. Aluminum radiators are especially intolerant of this.
• A closed heating system with forced circulation is less inert - it warms up much faster at start-up, much more sensitive to adjustments. Completely unjustified losses in the area of ​​the open expansion tank are excluded.
• The temperature difference in the supply pipe and in the return pipe in the currents connected to the boiler is less than in an open system. This is important for the safety and durability of heating equipment.
• A closed circuit with forced circulation to create circuits will require tons of smaller diameter pipes - there is a gain both in material costs and in simplifying installation work.
• An open-type expansion tank must be controlled to prevent overflow during filling, and to prevent the liquid level in it from falling below a critical level during operation. Of course, all this can be solved by installing additional devices, for example, float valves, overflow pipes, etc., but these are unnecessary complications. In a closed heating system, such problems do not arise.
• And, finally, such a system is the most versatile, as it is suitable for any type of battery, it allows you to connect underfloor heating circuits, convectors, and thermal curtains. In addition, if desired, hot heat supply can also be arranged by installing an indirect heating boiler in the system.

Of the serious shortcomings, only one can be mentioned. This is an obligatory "safety group", including instrumentation (pressure gauge, thermometer), safety valve and automatic air vent. However, this, rather, is not not a wealth, but a technological cost that ensures the safe operation of the heating system.

In a word, the advantages of a closed system clearly outweigh, and spending on a special hermetic expansion tank looks quite justified.

How is the expansion tank for closed-type heating arranged and how does it work?

The expansion tank device for a closed-type system is not very complicated:

Usually the whole structure is placed in a steel stamped case (pos. 1) of a cylindrical shape (there are tanks in the form of a “tablet”). For the manufacture of high-quality metal with an anti-corrosion coating is used. Outside the tank is covered with enamel. For heating, products with a red body are used. (There are blue tanks - but these are water batteries for the water supply system. They are not designed for elevated temperatures, and all their parts are subject to increased sanitary and hygienic requirements).

On one side of the tank there is a threaded pipe (pos. 2) for tapping into the heating system. Sometimes fittings are included in the package to facilitate installation work.

On the opposite side there is a nipple valve (pos. 3), which serves to pre-create the necessary pressure in the air chamber.

Inside, the entire cavity of the tank is divided by a membrane (pos. 6) into two chambers. On the side of the branch pipe there is a chamber for the coolant (pos. 4), on the opposite side - an air chamber (pos. 5)

The membrane is made of an elastic material with a low diffusion index. It is given a special shape, which provides an "ordered" deformation when the pressure in the chambers changes.

The principle of operation is simple.

• In the initial position, when the tank is connected to the system and filled with coolant, a certain volume of liquid enters the water chamber through the pipe. The pressure in the chambers equalizes, and this closed system takes on a static position.
• With an increase in temperature, the volume of the coolant in the heating system expands, accompanied by an increase in pressure. Excess liquid enters the expansion tank (red arrow), and bends the membrane with its pressure (yellow arrow). At the same time, the volume of the chamber for the coolant increases, and the volume of the chamber for the air, respectively, decreases, and the air pressure in it increases.
• With a decrease in temperature and a decrease in the total volume of the coolant, the excess pressure in the air chamber contributes to the movement of the membrane back (green arrow), and the coolant moves back into the pipes of the heating system (blue arrow).

If the pressure in the heating system reaches a critical threshold, then the valve in the "safety group" should work, which will release excess fluid. Some models of expansion tanks have their own safety valve.

Different models of tanks may have their own design features. So, they are non-separable or with the possibility of replacing the membrane (a special flange is provided for this). The kit may include brackets or clamps for mounting the tank on the wall, or there may be stands - legs for placing it on the floor.

In addition, they may differ in the design of the membrane itself.

On the left is an expansion tank with a membrane - diaphragm (it has already been discussed above). As a rule, these are non-separable models. Often a balloon-type membrane is used (figure on the right), made of an elastic material. In fact, it is itself a water chamber. As the pressure increases, such a membrane stretches, increasing in volume. It is these tanks that are equipped with a collapsible flange, which allows you to independently replace the membrane in the event of its failure. But the basic principle work does not change at all.

Video: device expansion tanks brand "Flexcon FLAMCO"

How to calculate the required parameters of the expansion tank?

When choosing an expansion tank for a particular heating system, its working volume should be a fundamental point.

Calculation by formulas

You can find recommendations to install a tank, the volume of which is approximately 10% of the total volume of coolant circulating through the circuits of the system. However, it is possible to carry out a more accurate calculation - for this there is a special formula:

Vb =Vwith ×k / D

The symbols in the formula are:

Vb- the required working volume of the expansion tank;

Vс- the total volume of the coolant in the heating system;

k- coefficient taking into account the volumetric expansion of the coolant during heating;

D- coefficient of efficiency of the expansion tank.

Where to get the initial values? Let's go in order:

1. The total volume of the system ( VWith) can be defined in several ways:

• It is possible to detect by the water meter what total volume will fit when the system is filled with water.
• The most accurate method that is used in calculating the heating system is the summation of the total volume of pipes of all circuits, the capacity of the heat exchanger of the existing boiler (it is indicated in the passport data), and the volume of all heat exchange devices in the premises - radiators, convectors, etc.
• Quite acceptable error gives the simplest way. It is based on the fact that 15 liters of coolant are required to provide 1 kW of heating power. Thus, the nominal power of the boiler is simply multiplied by 15.

2. The value of the coefficient of thermal expansion ( k) is a tabular value. It varies non-linearly depending on the heating temperature of the liquid and on the percentage of antifreeze in it. ethylene glycol additives. The values ​​are shown in the table below. The heating value line is taken from the calculation of the planned operating temperature of the heating system. For water, the value of the percentage of ethylene glycol is taken - 0. For antifreeze - based on a specific concentration.

Heat carrier heating temperature, °C	Glycol content, % of total volume
	0	10	20	30	40	50	70	90
0	0.00013	0.0032	0.0064	0.0096	0.0128	0.016	0.0224	0.0288
10	0.00027	0.0034	0.0066	0.0098	0.013	0.0162	0.0226	0.029
20	0.00177	0.0048	0.008	0.0112	0.0144	0.0176	0.024	0.0304
30	0.00435	0.0074	0.0106	0.0138	0.017	0.0202	0.0266	0.033
40	0.0078	0.0109	0.0141	0.0173	0.0205	0.0237	0.0301	0.0365
50	0.0121	0.0151	0.0183	0.0215	0.0247	0.0279	0.0343	0.0407
60	0.0171	0.0201	0.0232	0.0263	0.0294	0.0325	0.0387	0.0449
70	0.0227	0.0258	0.0288	0.0318	0.0348	0.0378	0.0438	0.0498
80	0.029	0.032	0.0349	0.0378	0.0407	0.0436	0.0494	0.0552
90	0.0359	0.0389	0.0417	0.0445	0.0473	0.0501	0.0557	0.0613
100	0.0434	0.0465	0.0491	0.0517	0.0543	0.0569	0.0621	0.0729

3. The value of the efficiency coefficient of the expansion tank ( D) will have to be calculated using a separate formula:

D = (Qm – Qb) / (Qm + 1)

Qm- the maximum allowable pressure in the heating system. It will be determined by the threshold of the safety valve in the "safety group", which must be indicated in the product passport.

Qb- pre-pumping pressure of the air chamber of the expansion tank. It can also be indicated on the packaging and in the product documentation. It is possible to change it - pumping with a car pump or, conversely, bleeding through a nipple. It is usually recommended to set this pressure within 1.0 – Indicate the nameplate power of the heating boiler, kW, based on the intended location of the expansion tank - with fastening to the wall or with placement on the floor.

There is one more nuance. Some heating boilers have their own built-in expansion tank. This does not mean at all that it is not necessary to carry out calculations - it happens that the volume of the built-in tank is clearly not enough. In this case, you will have to purchase and install an additional one, with a working volume equal to the difference between the calculated indicators for the entire system and the parameters in the built-in tank.

And one more note. If the heating system works on the principle of forced circulation, then, even with small volumes of coolant, an expansion tank with a capacity of at least 15 liters should be installed.

Expansion tank for closed-type heating do-it-yourself installation

For a person with plumbing skills, installing an expansion tank on their own will not be difficult. The principle of its insertion into the system is shown in the diagram:

On the return pipe (pos. 1), in the area as close as possible to the entrance to the heating boiler (pos. 2), but usually in front of the circulation pump (pos. 3), a cut is made into which the tee is packed (pos. 4). The installation method can be different - it all depends on the type of pipes used - metal, polypropylene or metollaplast.

A ball valve (pos. 7) is packed on the branch pipe (pos. 6) of the expansion tank itself (pos. 5). It is necessary in order to ensure the possibility of shutting down the expansion tank in case of need for repair or maintenance work. For the same purposes, it makes sense to place a connection with a union nut - “American” (pos. 8) between the tap and the tank. In working position, the valve must be constantly open.

From the tap there is a connecting section of the pipe (pos. 9) to the tee. Its length and configuration (number of bends or turns) they don’t matter much - but it’s usually done along the shortest and most convenient path from the installation site of the tank to the return pipe.

Now let's see what needs to be done on the tank itself.

Illustration	Brief description of the operation to be performed
	The tank was taken out of the factory packaging, the necessary tools and accessories were prepared for work.
	If necessary, an adapter is packed on the threaded pipe of the expansion tank. It is important to achieve exceptionally reliable sealing of the joints. It is best to pack on tow using Unipack paste or using a special thread sealing thread (cord) impregnated with a sealing compound (as shown in the figure).
	The adapter is tightened, and you can proceed to the installation of the crane. It should be noted right away that in the example shown, a flaw was made - the master does not establish a detachable connection - "American" between the tap and the tank. That is, if it is necessary to dismantle the tank with the tap closed, this will be very difficult to do. Recommendation to all installers - do not forget about this moment.
	A thread is being wound for packing the crane, ...
	... the valve is put in place and tightened tightly. It should immediately be provided that the “lamb” is in a position convenient for use after placing the tank on the wall.
	From the tap, a transition is mounted to the pipe of the required configuration, in accordance with the drawn up scheme for the general installation of the expansion tank. In fact, this part of the work is finished.
	Now you can check the pressure in the air chamber of the expansion tank. On its opposite side there is a nipple - almost exactly the same as on car wheels. In many models, it is covered with a special plastic cap, which, if necessary, access to the valve is simply unscrewed.
	You can check the pressure with a car pressure gauge. If it exceeds the indicators that were used in the calculation of the system, then it can be bled to the required level by pressing the valve stem. In case of insufficiency, you will have to pump up - an automobile pump is quite suitable for this.
	In the considered version, the tank already has devices for its placement, even in two versions - legs for installation on a horizontal surface (blue arrows) and a mounting plate for hanging on a wall (yellow arrow). The tank is mounted in the selected location, and then connected by a pipe section to a tee embedded in the return line. On this installation can be considered complete.
	Another version of the tank, on the body of which there are no structural elements for fastening at the installation site. But they, as a rule, are included in separate parts in the package.
	Usually this is a bracket - a mounting platform for attaching to the wall, and a long screw band clamp.
	The summer of the clamp is straightened and threaded into the slots of the mounting platform.
	All this is done in such a way that the protruding side of the tank falls into a special groove of the mounting platform (shown by arrows), and the clamp is higher than the side.
	After installing the tank in the mounting area, the ends of the clamp are connected, first tightened manually ...
	.. and then - until it stops, using a screwdriver or wrench.
	In this form, the tank will be ready for hanging on the wall.
	Installation of plumbing fittings to the tank pipe is carried out in the same order as already mentioned above.
	The nipple is located openly, only with a dustproof plastic cap. Checking pressure and pumping, if necessary, is no different from the previously considered option.
	By the way, tanks usually come from the factory with a pre-set pressure in the air chamber, and you can immediately select the desired parameter. It is indicated on the packaging and in the technical documentation of the product. Further installation of the tank is carried out in the already known order - mounting on the wall in the selected place and connecting the pipe with a tee.

After the final installation, be sure to open the tap and fill the system with coolant. If no leaks are found in the connecting nodes, the installation of the expansion tank can be considered complete.

Video: inserting an expansion tank into a polypropylene pipe circuit

At the end of the article, it must be emphasized once again that a closed heating system with a sealed expansion tank must necessarily have a reliable “safety group”. If it is located in a place that is not very convenient for regular visual control, it makes sense to install an additional pressure gauge in the immediate vicinity of the expansion tank - it will be much easier to monitor the condition of the entire system.