Open type expansion tank for heating - types, types, application. How to choose an expansion tank for a heating system Which expansion tank to choose

An important part of the heating system is the expansion tank. This is the exit tank excess coolant, expanding when heated.

Without an expansion tank it is impossible correct functioning any heating system.

Purpose of the expansion tank for boilers

At the moment of heating the volume of any body increases.

This is due to the physical properties of the substance. Liquid bodies, and in pipes and heating radiators these are coolants, when heated for every 10 °C increase approximately by 0.3%.

Since liquid cannot be compressed, then its surplus appears that need to be sent somewhere. For this, an expansion tank is installed.

This device receives excess liquid from the heating pipes and makes up for the lack of coolant when it cools and, as a result, contracts.

Important! In the absence of an expansion tank, during heating of the coolant, increase in pressure, which leads to rupture of pipes and radiators.

The expansion tank provides safe operation of all components of the heating system.

It depends on its correct installation life time. Thus, the reservoir is needed in order to:

• temporarily remove excess coolant from the heating system when it is heated;
• remove excess liquid from the reservoir when the maximum level is exceeded;
• make up for the lack of coolant in the pipes when cooling;
• maintain heating system pressure by adjusting the coolant volume;
• accumulate and release air and vapors from a liquid into the atmosphere, which appear when it is heated.

Types of tanks

Exists two kinds heating system tanks:

• open;
• closed.

Open

Installed in systems with natural coolant circulation. It is mounted at the highest point and represents open or half-open container round or rectangular shape.

At a certain level, a tube is inserted into it to drain excess coolant. Open tank be sure to insulate so that the coolant does not cool down.

Photo 1. Open type expansion tank, suitable for heating systems with natural circulation.

Advantages:

• simplicity and unpretentiousness of maintenance;
• lack of additional elements;
• Ease of Management.

Flaws:

• openness and contact with the atmosphere, as a result of which corrosion of the device itself is possible;
• due to openness observed large evaporation of coolant, which leads to the need for constant monitoring of the liquid level;
• installation at the top point of the main riser delivers inconvenience when adding liquid to the system.

Closed

A closed-type reservoir is installed in heating systems with forced circulation of coolant. He is sealed container with installed Mayevsky tap to vent excess air. To monitor the pressure inside the tank, it is equipped with a barometer. Such a tank can be installed anywhere in the room.

Photo 2. A closed expansion tank is usually installed in heating systems with forced circulation.

Advantages:

• complete tightness of the system;
• , which eliminates corrosion of pipes and radiators;
• ease of installation;
• efficiency.

Flaws:

• the need to install additional equipment to control the pressure inside the container;
• risk of damage to the device due to pressure surges.

Membrane

Membrane type tanks - a separate type of closed tanks. They represent sealed container with an elastic membrane inside.

The membrane serves to regulate the fluid pressure in the system. She divides the tank into two parts. One part is filled with inert gas, and the other is designed to receive excess coolant.

When liquid enters one part, the pressure on the membrane increases, as a result of which it moves towards the side where the air is located. When the coolant cools, the reverse process occurs. The pressure from the liquid side decreases, and the compressed air pushes the membrane back.

Membrane containers can have replaceable and non-replaceable membrane. In the second case, if it breaks down, you will have to replace the expansion tank completely, which is why containers of the first type are more popular.

Advantages:

• no contact with air and, as a result, preventing metal corrosion;
• installation in any convenient place indoors;
• no need for thermal insulation;
• ease of installation;
• reliability;
• efficiency, because the coolant does not evaporate from pipes and radiators and is not cooled.

Flaws:

• impossibility of making it yourself without special materials and tools;
• periodic checking of inert gas pressure;
• in case of structural failure in some cases you will have to replace the entire tank.

Reference! Membrane tanks are installed in closed heating systems using pump. Such systems depend on the availability of electricity.

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How to calculate the volume of the tank

When calculating the volume of the expansion tank, several factors must be taken into account:

To calculate the tank capacity, the formula is used:

Vb=(Vc * K)/D, where:

Vb— tank capacity;

Vс— volume of coolant in the system;

TO— liquid expansion coefficient. For water, this figure is 4%, so the formula uses 1,04;

D— the expansion coefficient of the tank itself depends on the material of manufacture and the temperature difference during heating. To accurately determine “D” you can use the formula:

D = (Pmax - Pstart)/ (Pmax + 1), where:

Pmax— this is the value of the maximum pressure inside pipes and radiators;

Rnach is the pressure inside the tank planned by the manufacturers ( usually 1.5 atm.).

Thus, the volume of the tank depends largely on its own characteristics.

Attention! All indicators and characteristics should not be above established standards. When calculating the volume of the device, the data should be equal to or slightly greater than the results obtained.

Many sites offer online payments expansion tanks.

Installation in a private house

When connecting the tank to the heating of a private house, you should decide on its type. Each type of connection is made according to the instructions and has its own characteristics.

Features of connecting an open type container:

• installed directly above the boiler at the highest point of the riser;
• the tank body is carefully insulated;
• An emergency liquid drain must be equipped.

Important! It is better to direct the emergency drain into the sewer, to prevent living creatures from falling under the hot stream of coolant.

Features of installation of closed and membrane type tanks.

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

Water has low compressibility, so a special device is built into the system - a membrane or open tank. Its function is that as pressure increases, air will be compressed. This makes it possible to provide protection against water hammer. An installed expansion tank protects the system from excessive pressure build-up.

The main task is to perform reliable installation of the tank

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 to prevent air from coming into contact with the coolant. Otherwise, airing of the network and an increased risk of corrosion of steel elements of the system cannot be avoided.

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

How to connect an expansion tank

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

The operating principle 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 flows by gravity into the heating radiators and, when cooled, 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.

When considering this diagram, it becomes obvious that the only possible installation 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 for a membrane tank in an open type heating system

As a tank, you can use any container of a suitable size made of heat-resistant material. A lid (not sealed) is needed only to protect it from debris getting into the system. If you don’t have a small metal barrel 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 of the house.

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

Expansion tank in a closed heating system

Equipment for the heating system is selected at the design stage, taking into account the requirements for the performance of the boiler unit, the length of pipelines and the volume of coolant involved. A diagram is being developed that indicates the installation locations of all system elements, including the expansion tank. In a closed heating system, it is necessary to use a membrane device.

Expander in a closed heating system

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

• The tank should be placed in such a way as to ensure normal access for installation and further maintenance. Floor-standing models are not recommended to be installed close to the wall.
• If the device 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. Typically, 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 should not be placed on the floor across the passage or suspended at human height.
• The pipes connected to the expansion tank must be secured to the wall. It is important to avoid a situation where the load from them and from the shut-off valves falls on the tank pipes. Separate mounting of pipes and taps makes it easier to replace the expansion device in case of failure.

At the equipment selection stage, 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 liquid circulating in the system. It is permissible to use a larger tank. But a tank that is not large enough can become a source of problems, since it is not able to compensate for the increased pressure in the system.

Rules for placing the expansion tank

For approximate calculations of the volume of coolant in the system, you can take the thermal power of the boiler unit as a basis. On average, 15 liters of liquid are used per kilowatt. Exact calculations are made taking into account the length of pipelines, 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. There is no need to purchase a separate tank 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, thanks to which excess pressure is automatically released. If one is not provided for by the design of the device, you should buy a safety valve separately and install it in close proximity to the tank.

Where is the best place to put the tank?

The optimal place for installing a membrane tank is a straight section of the pipeline, which is characterized by laminar flow of water, that is, the absence or minimal amount of turbulence. A convenient place is the spill area near the circulation pump.

Note! The expansion tank of a closed heating system can be installed at any convenient height. There is no need to place it at the highest point, since it functions solely as a surge protector. Unlike an open-type heating system, the air accumulated in the pipeline is released 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 tank placement

If desired, the tank can be placed on the supply line; this will not affect the operational properties of the heating system. But the membrane tank itself will not last a relatively long time, since the polymer membrane will be in constant contact with the coolant that 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 not recommended if the heating 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, which is why the membrane will not be able to 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 connection. This installation principle makes it possible, if necessary, to shut off the flow of water in the system at any time, remove the faulty membrane tank and install a new one.

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

By hanging the expander upside down, if the diaphragm malfunctions, the unit will fail immediately

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

However, it is worth considering this point: if the air compartment is located at the bottom, 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 positioned with the air chamber upward, its service life is extended. Over time, from constant contact with hot water, the polymer membrane loses its tightness and cracks appear in it. If the air chamber is located at the bottom, then water will immediately begin to seep into the air compartment, which will quickly damage the expansion tank, while air will penetrate into the coolant. When the air chamber is located on top, the diffusion of water through cracks occurs many times slower, and the device can operate much longer.

Useful tips:

• If you install a pressure gauge next to the expansion tank and the valve, thanks to which the heating system is fed from the water supply, it will allow you to control the pressure in the system in order to bleed off excess in time if the safety valve spool is stuck and does not operate automatically.
• Frequently repeated release of pressure by the valve indicates that the capacity of the expansion tank is selected incorrectly. Instead of changing it to a larger tank, just 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 circuit of the expansion tank should be equipped with a safety group

Settings

Before connecting the tank and filling it with coolant, you need to check the pressure level in the air chamber of the tank - it must correspond to the pressure in the heating system. For this purpose, you should remove or unscrew the plastic plug that covers the spool valve (similar to those installed in car cameras). Using a pressure gauge, 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 a pump or, vice versa, it is bleed by pressing the spool rod.

Note! The tank should be adjusted so that the pressure in its air chamber is 0.2 bar less than the design pressure in the system filled with coolant. If the pear-shaped membrane is not pressed on the water injection side, the coolant, compressing during the cooling process, 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 starts up.

The adjustment step is not required if the factory pressure in the air compartment of the expansion tank corresponds to the required parameters. Manufacturers of some brands of equipment indicate the pressure level in the tank on the packaging, which makes it possible to select the optimal option when purchasing.

Conclusion

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

An expansion tank for closed heating is considered one of the most important elements of engineering systems in a country house. You can buy it in a specialized store in any locality. The cost of such a device is quite high, so people with little financial resources prefer to make it themselves at home.

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General information

Before you begin purchasing and installing the product, you need to decide where the expansion tank will be located and how best to install it. In addition, you should definitely take into account all the technical specifications and study the operating rules in detail.

How and where to install a heating expansion tank



Design elements

The design of an expansion tank for a heating system is distinguished by its simplicity and minimal number of elements. All this allows us to reduce the cost of the structure and simplify its installation in a private home.

The expansion tank consists of the following parts:

1. 1. Stamped body. It has a cylindrical shape and is made of various types of steel. In the process of creating this element, only high-quality material is used that has the necessary characteristics (resistance to elevated temperatures, strength). The inside of the body is coated with an anti-corrosion compound, and the outside is coated with enamel. All this allows you to extend its service life and prevent emergency situations.
2. 2. Fittings (the connecting part of a pipeline installed for branching, turning, transitions to another diameter, as well as if frequent assembly and disassembly of pipes is necessary). They are used to simplify the installation process and achieve better sealing of the system.
3. 3. Threaded pipe. This part is used for insertion into the heating system and is located on one side of the tank.
4. 4. Nipple valve. It is installed on the opposite side and acts as a device that creates the required pressure in the air chamber.
5. 5. Separating membrane. This element is located in the inside of the expander and divides it into 2 compartments. A chamber is formed near the pipe for the coolant, and on the other side for air. Typically, the membrane is made of a material that has good elasticity and low diffusion. It has a certain shape, which helps to deform during pressure surges in one of the chambers.






Operating principle

The operation scheme of a closed expansion tank is quite simple. Not only a specialist, but also a beginner who has a basic understanding of the process can understand it.

The device fulfills its obligations in the following way:



If a sharp increase in pressure occurs and its indicators reach the limit values, then a special valve is activated, which releases part of the liquid. Thanks to this, the pressure is normalized and the risk of an accident is reduced.

Correct filling of a closed heating system.



Advantages and disadvantages

A closed expansion tank, like any other product, has its advantages and disadvantages. They must be taken into account before installation, which will avoid unforeseen situations that can bring many problems to the owners of a private home.

Among the advantages are the following:



Despite the large number of advantages, a closed expansion tank also has several disadvantages. They lead to increased financial costs and decreased efficiency.

The negative aspects include:



Where to install the expansion tank correctly

Installation stages

In order for the expander to work efficiently and not cause an accident, it must be installed correctly. To do this, you need to carry out a number of preparatory measures that will significantly simplify the process and reduce the risk of making mistakes.

Volume calculation

Professionals advise using an expansion tank, which will increase the total volume by about 10%. This will be enough for the normal and uninterrupted functioning of the entire heating system. If glycol, rather than water, is used as a coolant, then this figure should be increased to 50%. This large difference is due to the expansion coefficient. The same applies to open type vacuum tanks.

The calculation can be carried out in the following ways:



Operating principle and selection of expansion tank

Basic Rules

To ensure high efficiency and maximum safety, it is necessary to take into account the basic rules for installing a closed heating expansion tank. In addition, they will help to avoid negative consequences and eliminate the likelihood of breakdowns during operation.

1. 1. Experts recommend installing such structures on the return line in front of the circulation pump (relative to the direction of movement of the coolant). If such an arrangement is not possible, then a straight horizontal section is selected.
2. 2. It is best to connect an expander that has a built-in safety valve. With its help, it will be possible to relieve pressure in the system and avoid an emergency.
3. 3. If the safety valve operates frequently, it is necessary to replace the expander with a larger reservoir. Another way out of the situation would be the parallel installation of an additional tank.
4. 4. The tank must be equipped with a pressure gauge, which will simplify monitoring the operation of the device.

Heating is the key life support system of a private home and its stable operation is very important. One of the parameters that needs to be monitored is blood pressure. If it is too low, the boiler will not work; if it is too high, the equipment will wear out too quickly. To stabilize the pressure in the system, an expansion tank for heating is required. The device is simple, but without it the heating will not work for a long time.

Why do you need an expansion tank for heating?

When the heating system operates, the coolant often changes its temperature - it either heats up or cools down. It is clear that the volume of liquid changes. It either increases or decreases. Excess coolant is forced out into the expansion tank. So the purpose of this device is to compensate for changes in the volume of coolant.

Types and device

There are two water heating systems - open and closed. In a closed system, coolant circulation is provided by a circulation pump. It does not create additional pressure, it simply pushes water at a given speed through the pipes. In such a heating system there is a closed expansion tank for heating. It is called closed because it is a sealed container, which is divided into two parts by an elastic membrane. In one part there is air, in the other the excess coolant is displaced. Due to the presence of a membrane, the tank is also called a membrane tank.

An open heating system does not require a circulation pump. In this case, an expansion tank for heating is simply any container - even a bucket - to which heating pipes are connected. It doesn't even require a lid, although it may have one.

In the simplest version, it is a container welded from metal, which is installed in the attic. This option has a significant drawback. Since the tank is not sealed, the coolant evaporates and it is necessary to monitor its quantity - top up all the time. This can be done manually - from a bucket. This is not very convenient - there is a risk of forgetting to replenish water supplies. This threatens to cause the system to become airy, which can lead to its breakdown.

Automated water level control is more convenient. True, then, in addition to the heating pipes, you will also have to run a water supply into the attic and also somewhere to route the overflow hose (pipe) in case the tank overflows. But there is no need to regularly check the amount of coolant.

Volume calculation

There is a very simple method for determining the volume of an expansion tank for heating: 10% of the volume of coolant in the system is calculated. You should have calculated it when developing the project. If this data is not available, you can determine the volume experimentally - drain the coolant, and then fill in a new one, measuring it at the same time (put it through a meter). The second way is to calculate. Determine in the system, add the volume of radiators. This will be the volume of the heating system. From this figure we find 10%.

Formula

The second way to determine the volume of an expansion tank for heating is to calculate it using the formula. Here you will also need the system volume (indicated by the letter C), but other data will also be needed:

• the maximum pressure Pmax at which the system can operate (usually the maximum boiler pressure is taken);
• initial pressure Pmin - from which the system begins operation (this is the pressure in the expansion tank, indicated in the passport);
• coolant expansion coefficient E (for water 0.04 or 0.05, for antifreeze it is indicated on the label, but usually in the range of 0.1-0.13);

Having all these values, we calculate the exact volume of the expansion tank for the heating system using the formula:

The calculations are not very complicated, but is it worth bothering with them? If the system is open, the answer is clear - no. The cost of the container does not depend very much on the volume, plus you can make it yourself.

Expansion tanks for closed type heating are worth counting. Their price depends greatly on volume. But, in this case, it is better to take it with a reserve, since insufficient volume leads to rapid wear of the system or even its failure.

If the boiler has an expansion tank, but its capacity is not enough for your system, install a second one. In total, they should give the required volume (the installation is no different).

What will result from insufficient expansion tank volume?

When heated, the coolant expands, its excess ends up in the expansion tank for heating. If all the excess does not fit, it is released through the emergency pressure relief valve. That is, the coolant goes into the sewer.

Then, when the temperature drops, the volume of coolant decreases. But since there is already less of it in the system than there was, the pressure in the system drops. If the lack of volume is insignificant, such a decrease may not be critical, but if it is too small, the boiler may not work. This equipment has a lower pressure limit at which it is operational. When the lower limit is reached, the equipment is locked. If you are at home at this time, you can correct the situation by adding coolant. If you are not there, the system may unfreeze. By the way, working at the limit also does not lead to anything good - the equipment quickly breaks down. Therefore, it is better to play it safe and take a slightly larger volume.

Tank pressure

In some boilers (usually gas ones), the passport indicates what pressure must be set on the expander. If there is no such record, for normal operation of the system, the pressure in the tank should be 0.2-0.3 atm lower than the working one.

The heating system of a low-rise private house usually operates at 1.5-1.8 atm. Accordingly, there should be 1.2-1.6 atm in the tank. The pressure is measured with a conventional pressure gauge, which is connected to a nipple located in the upper part of the container. The nipple is hidden under a plastic cover; unscrew it and gain access to the spool. You can also relieve excess pressure through it. The principle of operation is the same as that of a car spool - you bend the plate with something thin, bleeding the air to the required levels.

You can also increase the pressure in the expansion tank. To do this, you will need a car pump with a pressure gauge. Connect it to the nipple and pump it up to the required readings.

All of the above procedures are carried out with the tank disconnected from the system. If it is already installed, there is no need to remove it. You can check the pressure in the expansion tank of the heating system on site. Just be careful! It is necessary to check and adjust the pressure in the expansion tank for heating when the system is not working and the coolant has been drained from the boiler. For the accuracy of measurements and tank settings, it is important that the pressure on the boiler is zero. That’s why we drain the water carefully. Then we connect the pump with a pressure gauge and adjust the parameters.

Where to put it in the system

The expansion tank in a closed system is placed after the boiler before the pump, that is, so that it creates a flow in the opposite direction. This way the system works more reliably. So the specific installation location depends on where you have the circulation pump.

It is connected to the system via a tee. You cut a tee into the pipe, direct the perpendicular outlet upward, and screw the tank onto it. If the wall does not allow you to place a container, you will have to make an elbow, but the tank will be turned upward. Now we can assume that the expansion tank is installed.

But for the convenience of checking, it is advisable to install another tee after the tank, and install a shut-off valve on the free outlet of it. This makes it possible to check the membrane tank without draining the entire system - it cuts off the tank. Turn off the tap and bleed water from the boiler. Check the pressure on the disconnected branch (in the boiler). It must be zero. Afterwards, you can carry out all other setup work.

A properly selected and connected expansion tank for closed-type heating plays an important role. It will protect the heating circuit and extend the operating life of the equipment. A closed, sealed container will eliminate the need to endlessly repair the system and change devices. It's worth getting to know her. Is it true?

We will tell you how to choose a closed expansion tank model in accordance with the technical data of the system. We'll show you how to install and connect it correctly. In addition, the article provides recommendations that must be followed to extend the life of the equipment.

All of them, regardless of volume and performance, are designed to level out the expansion (special liquids, water) that occurs when its temperature increases.

This is done in order to avoid destructive damage to fittings, fittings, rupture of pipes, and extrusion of gaskets.

Any closed tank is a sealed steel tank, divided into parts by an elastic membrane, which changes its position as the temperature of the coolant increases/decreases

Example: the coolant (water) expands by four percent as the temperature rises to 95 °C. Which is quite enough for the engineering system to fail.

Expanzomat design and components

Any such modern product consists of the following structural elements:

• housings;
• coolant chambers;
• a gas chamber into which ordinary air or inert gas is pumped;
• membranes.

The option of filling the gas chamber with inert gas is more preferable, because it provides the container with greater durability. But regular air is more accessible.

The membrane is made of elastic materials, therefore it is able to change its position as the temperature of the coolant increases or decreases. This structural element can be of the diaphragm or balloon type, and their operating principle is similar.

The tanks are connected to the heating system using a special pipe. A valve is provided for pumping gas. Closed-type containers are manufactured in a horizontal or vertical layout, which makes it easier to complete the heating system.

The reason is that when the pressure rises to critical standards, the device will start working and bleed it. That is, this valve can significantly increase the safety of the entire heating system.

When purchasing a container, you should take into account that red paint is most often used to mark expansion tanks used for heating.

This feature will help to distinguish the desired product from other similar ones, for example, water supply tanks of similar size and shape - which are predominantly covered with blue enamel.

But if necessary, you can find tanks of various colors, which will help you place the one you need in any room without compromising its aesthetic qualities.

Containers can be horizontal or vertical, and manufacturers also provide the opportunity to mount them in different places. For this product, they are equipped with various accessories. And when purchasing, you should pay attention to this, determining the best option in advance.

When choosing, you should also pay attention to the quality of the materials used in the production of the container body and membrane. And the presence of a guarantee for the purchased equipment and instructions for installing and connecting it to the system.

How to install?

There are no significant restrictions affecting the place in the system. Nevertheless, it is advisable to carry out the installation at any convenient point in the return line of the existing heating system.

The reason is that the coolant there is cooler. And this allows you to significantly extend the life of the expansion tank and its membrane.

In addition, if you install the tank near a solid fuel boiler, then in certain situations steam may enter the coolant chamber. As a result, the container will lose the ability to compensate for the expansion of the coolant.

Installation of the tank can be done in two ways. These include installation:

• on the wall;
• on the floor.

But it should be understood that the first option is intended only for cases where the expansion tank has a moderate volume.

Tanks should be installed as far as possible from boilers. And the optimal solution would be to locate it in the return line. Since the coolant temperature there is noticeably lower, which eliminates premature failure of the membrane

You should not skimp on connecting the tank to the heating system.

So this procedure should be performed using:

• a shut-off valve with a so-called “American” - this design element will allow you to quickly remove the tank from service and, if necessary, replace it, without waiting for the coolant to cool down;
• a tee with a drain tap, which will allow you to quickly empty it before replacing the tank;
• pressure gauge for measuring pressure;
• safety valve or nipple to regulate the pressure inside the equipment.

After installing the tank, it must be configured correctly, taking into account the manufacturer’s recommendations given in the instructions for the purchased equipment. So that the pressure in the tank is appropriate, i.e. less than in the system, which will allow the membrane to deform when the coolant heats up.

If the calculations were carried out incorrectly and the heating system contains a tank of a smaller volume than required, then it will not cope with its duties, but the error can be corrected.

Why do you need to purchase and install a second container in the system? The capacity of which is the difference between the required volume and that available in the tank operating in the system. This method will reduce financial losses.

Operational Maintenance

It must be remembered that during breaks in use, the tanks, like other components of the heating system, should be emptied and then dried. This point should not be ignored, as failure to comply will lead to corrosion and reduced service life.

The main structural element that responds to changes in pressure from the coolant is an elastic membrane. Which is affected by a neutral gas (for example, nitrogen) or air on one side, and pressure from the coolant on the other. And the membrane takes position depending on which side has the stronger impact

When using any closed tank, owners should regularly perform a number of simple operations.

Which include:

• periodic inspections to detect corrosion and mechanical damage - this procedure should be carried out twice a year;
• checking the pressure in the system, which is performed every six months;
• periodic inspections of the integrity of the membrane - such operations are carried out according to the manufacturer’s recommendations.

And in addition, throughout the entire operation, users will have to comply with the requirements regarding permissible temperature and pressure standards.

To repair tanks, you should use only original components, as this will ensure not only the required performance, but also safety of use.

You can read about the rules and features of selecting an expansion tank for open-type heating systems, which owners of houses with open heating circuits should read.

Conclusions and useful video on the topic

The first video will help you understand the features of modern expansion tanks and their correct choice:

The following video will give you an opportunity to understand how to properly install a purchased expansion tank:

The closed cistern is a practical, durable, efficient and safe solution for the heating system. But in order to get the expected result, it is necessary to make the correct selection and installation of the product in the heating system and its configuration.

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