Water pump for heating: consider water pumps for heating a private house. How to choose a circulation pump
Heating systems with forced circulation are becoming increasingly popular among owners of country houses. Earlier we already talked about the main element of such a heating system, today we will talk about how to choose it correctly.
What are circulation pumps made of and their types?
- housing, on which the “snail” is installed;
- loop pipes, attached to the “snail”;
- electric motor, which has terminals for connecting to the network;
- rotor– a rotating structural element (on one side, the rotor sucks in the coolant, after which it pumps it into the loop pipes, as a result, the required pressure is formed at the pump outlet).
Using a circulation pump eliminates a number of problems. So, if during natural circulation the water in the last radiator is cold, and in nearby ones it is a little warm, then when the coolant flows back at a low temperature, it forces the boiler to work more intensely, sometimes even at the peak of its capabilities. Moreover, if mistakes were made when designing the heating system, the difference in temperature will be even more noticeable.
Benefits of using circulation pumps
- The requirements regarding the slope of the circuit pipes are significantly reduced.
- All traffic jams caused by temperature differences are eliminated.
- The room is heated evenly, since the coolant will be equally warm in all elements of the system.
- The boiler operation is stabilized.
- The pipeline diameter may be smaller.
Types of pumps
Taking into account the design features, circulation pumps were divided into two large groups - with dry and wet rotors.
Dry circulation The pumps differ in that the rotor in this case does not come into contact with the system coolant liquid during operation. Such devices are insulated with a special ring; they are characterized by a fairly high efficiency (about 80-85%), as well as a low noise level during operation. Dry pumps are larger in size than their wet-type “relatives,” and installation requires special piping of the circuit.
You might be interested in information on how to install
Dry-type circulation pumps are installed mainly in free-standing boiler houses serving a couple of houses or one industrial facility. Dry rotor units require regular maintenance.
Unlike them, wet pumps work for years without any maintenance. The rotor in them is in contact with the coolant; only the starter, the stationary element of the electric motor, is insulated. The advantage of such pumps is that the coolant is also a lubricant for the rotor, which is the main “secret” of durability and lack of noise during operation. Despite their low efficiency (often no more than 60%), they are convenient and compact, which is why they are so widely used in domestic heating systems.
In addition, according to according to the method of connecting the electric motor, circulation pumps are divided into:
- coupling pumps;
- pumps with flange connection.
Note! If all the pipes of the device (that is, pressure and suction) are located on the same axis, then this design is direct-flow. This means that the pump can be embedded directly into the line using a special frame for mounting.
Industrial circulation pumps are somewhat different from household ones.
Circulation pump prices
circulation pump
We have become familiar with the design features of pumps and their varieties, but it is still too early to rush to the store to make a purchase. You should also decide on the parameters that you need to pay attention to when choosing a particular model. "P , You can read in our article.”
Marking
The first thing we must you can see when you pick up the model you like - this is the marking that will be located under the name. It could be, for example, 32-50. The first number here is the connection dimensions, 32 mm or 1.25 inches. Often pumps are equipped with nuts of the required sizes, making it possible to quickly assemble/disassemble them.
The second number is the pump lift height. In our case, this is 5 m of water column or 0.5 atmosphere. There are pumps designed for higher or lower heights.
You might be interested in information about which one to choose
In addition, there must be a sign on the housing indicating what the maximum load should be and at what parameters. By parameters we mean performance - to adjust it, the pump has three positions. This is the second criterion for choosing a pump.
Performance
All requirements for a circulation pump are closely related. Under productivity refers to the volume of coolant distilled by the pump with minimal load on it. The higher the performance, the better the model.
In order to find out the required performance, we will use the popular formula:
N/(T 2 -T 1) = Q, Where
- T 1 – coolant temperature in the return pipeline;
- T 2 – its temperature in the supply pipeline;
- N – average power of the heating boiler;
- Q is the performance we need to calculate.
We take the average water temperature in the “return” (T 1) to be 65–70°C, while the temperature in the supply pipeline (T 2) will be approximately 95°C. This way we can approximately select the required parameters for the pump. It is believed that for every 10 m of pipeline you need 0.6 m pressure, or pump lift height.
In addition, there are already ready-made thermal standards. According to them, for every 10 m² of heated area, only 1 kW of power is needed. And if, for example, the power of one radiator battery is 200 W, then for 10 m² you will need five sections. But this number of sections is relative, since in most cases their number is larger, “with a margin”. Therefore, we need to take into account the fact that the circulation pump must cope with the supply of coolant to each radiator in the house.
Required power
The electrical power required to operate the pump is another parameter that you should pay attention to when purchasing. Often this power is insignificant - no more than 200 W. It is important only in cases where permanent use of the pump is planned.
How do external factors affect performance?
In addition to the indicated parameters, when purchasing, we need to take into account the influence of external factors on the operation of the pump, which certainly occur. First of all, this is the ambient temperature; the amount of thermal energy required to heat the house and the power of the device depend on it. Sometimes the environment also affects the pump itself: if it “freezes,” it will work somewhat worse than if it were “warmed up.”
Note! If the circulation pump is chosen incorrectly, it may not cope with the load and overheat. Therefore, before purchasing, we additionally study the technical characteristics of the heating system.
Also, the power of the pump depends on the diameter of the pipeline - the larger it is, the more powerful the device will be required. Moreover, if antifreeze, rather than water, is used as a coolant, then the circulation pump must be more powerful, because the viscosity of the antifreeze is different. It’s good that the range of pumps today is quite wide and allows you to choose a device for literally every heating system.
In order for a device to cope with the load, we must know whether it will work constantly. If this is not the case and the pump will only be turned on to feed the main system (or to correct pressure), then its high power is not a prerequisite. Of course, if we are talking about cutting into a circuit with natural ventilation, then the pump will be subject to high loads. Then, when choosing, we should be guided by the rule “the more powerful, the better.” If the pump power is not enough, the radiators will be barely warm, and the device itself may simply burn out.
Important point! If the pump is designed for a pipeline with a diameter of 1 inch, then you should not install it in pipes of larger diameter, even with special adapters. This often weakens the water pressure.
About the importance of the brand
There are a great many names of circulation pumps, but this does not prevent them all from having almost identical characteristics. And if there are significant differences, they relate mainly to reliability and service life.
The most popular brands today are Grundfos, Speroni, Wilo, ELSO-THERM and Wester. In addition to them, there are a lot of outright Chinese counterfeits and more (meaning “real” Chinese goods). The brands we list are considered by consumers to be the highest quality and most reliable. Circulation pumps from well-known manufacturers are almost silent. You can make sure that the device is working only by touching it, or by ear, but from a distance of a few centimeters. They are durable and can serve you for many years, but they have a significant drawback - high cost(it is almost twice as much as less popular models).
Other brands are a middle option. They work well, their prices are reasonable, and breakdowns are rare.
The opinions of all buyers about pumps from China agree: sooner or later the devices begin to make noise, the rotor begins to “walk”. Their service life sometimes reaches several years, but in most cases does not exceed several months. Naturally, they are inexpensive.
What to choose?
The answer is obvious - anything except Chinese pumps. If funds allow, then buy products from well-known companies; if not, then mid-price pumps are quite suitable.
Video - How to choose the right circulation pump?
FAQ
1. Will the pipes make noise when using the pump?
There can be noise in the pipes only if the device is chosen incorrectly or air has accumulated in the line. To remove air, do the following:
- fill the entire system with water;
- we remove air using valves on radiators - “air vents”;
- we start the heating boiler and pump;
- we wait for a while, after which we remove the air again;
- check the pressure, fill the circuit with water;
- we start the pump and adjust it (if it can be adjusted at all).
2. Is it possible to use a high pressure pump for water supply?
Definitely no! Even though they (pumps) look almost the same, in water supply pumping equipment is used solely to maintain the required pressure if for one reason or another it is not enough.
3. What are pumps made of?
Some parts (shaft, ball bearings) of modern pumps are made of ceramics. This not only ensures silent operation, but also significantly increases service life.
4. Are there pumps for hot water supply?
Yes, they exist. This is, for example, the GRUNDFOS Comfort UP circulation pump, thanks to which you don’t have to wait for hot water to start flowing from the tap. Of course, its use will increase the consumption of electricity and water itself.
5. How much energy do pumps consume?
In most cases, circulation pumps are extremely economical devices that consume as much energy as a regular light bulb. Recently, all pump manufacturers “agreed” to assign labels to their products indicating their “gluttony”, as is the case with household appliances. A classification has been developed according to which A-class devices, for example, need no more than 6 W.
Note! Adjustable pumps are more economical!
6. How often do circulation pumps need to be replaced?
If the pump is of high quality, it will last about ten years. Although, as we have already said, a lot depends on the manufacturer itself. To ensure that your device lasts longer, follow all recommendations regarding operation: select the correct model and install it, avoid airing the line, use only specially purified water as a coolant.
Video - Installation of a circulation pump
Choosing a pump for the heating system of a private house.
Heating systems, in which water moves through pipes due to its temperature and density - (by gravity) are becoming a thing of the past. There are many reasons for this, but the most important is the emergence of modern composite materials and pipes based on them. And the second important detail is the low efficiency of the heating system with natural circulation.
Our private households, dachas and country houses are increasing in size. It is simply impossible to build anything other than multi-circuit. A naturally well-balanced heating system, working due to natural circulation difficult to calculate and build. But is it worth building such a monster with fairly large pipe diameters, if enough install a circulation pump in the heating system .
At the same time, the pipes supplying heat to the heating devices become small in diameter and can be easily hidden in the wall or behind a plasterboard partition. Cast iron heating radiators, which have spoiled the appearance of our apartments all our lives, are being replaced with elegant bimetallic or aluminum ones. The volume of water in the heating system decreases, which means that the heating system warms up faster, and if there is a circulation pump in the heating system, the speed of water movement increases, the temperature difference between heating devices decreases, and as a result, the temperature in all rooms will be the same, which does not cause discomfort.
And probably most importantly Efficiency increases due to the circulation pump heating systems as a whole, which means that fuel consumption, which is becoming more expensive year after year, is reduced. And you can’t even dream of devices such as heated towel rails, thermostats, temperature controllers in each room, humidifiers and dehumidifiers in the absence of a circulation pump in the system.
Selecting a pump for a home heating system.
To selecting a circulation pump for a private home, cottage or cottage, you must take it very seriously. It would be better, of course, to entrust this to professionals, although if you have little basic knowledge and not too serious requirements for the heating system you can do the calculation yourself, based on our recommendations.
The circulation pump is selected according to the water flow in the heating system in m3 per hour and the developed pressure in M, based on the size of the house and the materials used in the construction of the house. will select the pump specifically for the heating system in your home. If you are ready to take responsibility when choosing, we recommend choosing a pump with automatic control or at least several operating speeds. It is of course more expensive, but it will allow you to correct errors in installing a heating system or choosing a circulation pump. Pumps with a so-called wet rotor have an adjustable rotation speed, and therefore it is possible to adjust the coolant circulation within certain limits and correct a mistake with the selection of a pump.
And so, to select a circulation pump for a private home, you need:
1. Know the height from the pump installation point to the top point of the topmost heating device.
2. Heated area of the room.
3. Determine the approximate resistance of your heating system. For example, let's start with it.
The so-called plastic pipes (Pilsa or PPR PN10, 20.25) are not specifically focused on the material - the properties are approximately the same. Diameter DN40 with cast iron batteries, heating system resistance 1m. DN 32 with aluminum heating radiators - 1.2 - 1.5 m. DN25 with bimetallic heating devices – 2m.
Select the pressure developed by the pump. For example, the height from the pump to the top point of the topmost heating device is 4 meters (the house has two floors, the pipes are thin, the heating devices are bimetallic), the pump must develop a pressure of 4+2 = 6 meters.
Now, to find m3/hour, we convert the heated power into the required heat. 10 m of heated area is 1 kW, if the walls are warm and thick we take 0.8 kW, thin and cold 1.2 kW.
The house is warm with an area of 200 m2, the walls are thick. 200/10x0.8=16 kW or 16x0.86=13.76 kcal
Now decide which one temperature difference in the heating system you need, we recommend 8-10 degrees, no more and no less. More is bad for the boiler and comfort; less, you will have to purchase a more powerful and expensive pump, which also consumes more electricity. We choose 10 degrees.
13.76/10=1.37 m3/hour
Therefore, for a warm two-story house with an area of 200 m2, with plastic pipes hidden in the walls and bimetallic radiators, you need a circulation pump with a capacity of 1.4 m3/hour at a pressure of 6 meters. To avoid errors, the circulation pump must have these characteristics at second speed, And you the pump should be selected as a three-speed one.
These conditions are met by a circulation pump with a wet rotor. UPS 25-70 from GRUNDFOS. Price branded pump 140 Euro, Chinese 70-80 Euro. It consumes 150 watts of electricity per hour.
If we used thicker pipes and aluminum radiators, then a UPS 25-60 180 circulation pump would be suitable, but it already costs 110 Euros. This pump consumes less electricity - 110 W per hour.
As you can see, it is better to design a heating system and select a circulation pump before starting work, so you can still save on materials and operating costs.
Paramonov Yu.O. Enterprise Energostrom LLC, 2013.
A circulation pump is a mandatory element of a forced circulation system. Thanks to its presence, it is possible to ensure uniform heating in all rooms of a private house. We invite you to get acquainted with the types and features of this equipment, as well as proven manufacturers and popular models. The editors of the online magazine site have prepared a review article about the advantages and disadvantages of this equipment, with a description of popular models and recommendations from specialists on choosing the best modification of the circulation pump for heating.
Read in the article
Where is a circulation pump used for heating a private home?
There are two types: with natural and forced circulation. The first type is relevant for houses whose square footage does not exceed 100 m². With a larger area, uniform heating of all is impossible. The coolant will move poorly through the pipeline, which will inevitably cause large heat losses.
The circulation pump, which is part of the heating system of the second type, ensures the movement of the coolant through the heating system at a certain speed. During the installation process, there is no need to control the slope of pipes, which may have a smaller diameter. Thanks to the forced circulation, it is possible to ensure uniform heating of various points of the heating circuit, and, as a result, of all rooms, regardless of their location relative to the room. The circulation pump for domestic hot water allows you to maintain water pressure at a given level.
Attention! Installing a circulation pump allows you to optimize the cost of servicing your heating system.
Design of a circulation pump for a heating boiler
The design of the pumps is almost identical. They consist of a body made of stainless alloy. Inside it there is an electric motor, on the shaft of which an impeller is attached. Various materials can be used for its manufacture. Thanks to the rotation of the blade wheel (impeller) in a special chamber (volute), the movement of the coolant through the elements of the heating system is ensured.
The principle of operation of the circulation pump
The operating principle of the circulation pump is based on the use of a centrifugal circuit. Rotating, the impeller throws the incoming coolant flow to the edges of the chamber. The centrifugal force that occurs when the wheel rotates creates a discharged area in the center. At the outlet, the pressure increases. This is enough to ensure stable flow circulation through the heating circuit.
Dependence of the operating principle of the heating system and pump selection
With the right choice of circulation pump, heating costs are significantly reduced. When choosing a suitable model, you should focus on the type of heating system, as well as its characteristics. Natural circulation systems are unable to distribute heat efficiently, which will inevitably result in some rooms being slightly warm and others being slightly hot. A properly selected one can create sufficient pressure to uniformly heat the heating circuit.
An open heating system with circulation pump is equipped with. The presence allows you to prevent heat supply shutdowns in the absence of light. In closed systems, the amount of coolant remains unchanged, which allows you to better select the pump model.
Types of circulation pumps for heating systems
Manufacturers offer equipment with different designs that determine the order of its operation and maintenance. We invite you to get acquainted with existing species and their distinctive features.
Dry pumps
The name of the equipment is dictated by its design features. The coolant is in contact only with the impeller. The rotor is located in a sealed housing, into which liquid does not enter due to the installation of several o-rings. Circulation pumps of this type have a fairly high efficiency, reaching 80%. They require regular maintenance, since the solid particles contained in the coolant negatively affect the sealing rings, causing depressurization of the rotor housing.
On average, “dry” pumps can last about 3 years. During operation, they make quite a lot of noise, which can create some inconvenience during operation. That is why they are practically not used in the heating system of a private home. However, in large networks their installation is completely justified economically.
Can be:
- horizontal;
- vertical;
- block.
Circulation pump with wet rotor
In devices of this type, the coolant is in contact with both the impeller and the rotor. The metal sealed glass contains only the electrical part along with the starter. The efficiency of a circulation pump with a “wet” rotor is about 50%. Such equipment does not require regular maintenance.
A comment
Leading engineer for heating, ventilation and air conditioning LLC "GK "Spetsstroy"
Ask a Question“Depending on the model and operating conditions, equipment with a wet rotor can last 5–10 years.”
During operation they make virtually no noise, which makes them the best option for a private house or apartment.
Technical characteristics of circulation pumps for heating systems
The selection of a suitable model for a specific circuit is made taking into account the technical characteristics of the circulation pump for heating systems. It is worth paying attention:
- productivity, showing how much liquid can pass through the pump in an hour of operation. Expressed in m³/h. Depends on hydraulic resistance;
- under pressure which, in essence, is hydraulic resistance. Characterizes the height to which a column of water can be raised;
- connecting dimensions. Depends on the diameter of the pipeline and installation location. If there is not enough space, it is worth purchasing the smallest circulation pump for heating;
- maximum temperature. Considering that the circulation pump constantly pumps liquid heated to a certain temperature, the maximum value requirements must be met. For budget models, the working fluid can heat up to a maximum of 90°C. In more expensive ones - up to 130°C;
- to the manufacturer. The preferred option would be products from trusted manufacturers.
Not everyone knows how to choose a circulation pump for heating. A table with reference data will help you choose the appropriate model.
How to choose a circulation pump for heating a private house
The characteristics of any equipment are selected taking into account the conditions of its future operation. How to choose a pump for heating a private house? You can use reference tables that provide the necessary information depending on the square footage of the building. If this option does not suit you, it is worth performing a calculation that will allow you to obtain more accurate values.
Pump performance calculation
G = M / ΔT × St , Where:
- M – power that will be used to heat the house, W;
- ΔT – temperature difference in the heating circuit;
- St – coefficient depending on the specific heat capacity of the coolant.
Power can be determined based on the fact that for each m² of a cottage or country house, 100 W of power is required, for multi-apartment buildings - 70 W. If there is additional thermal insulation of the external walls, the power is obtained by multiplying 50 kW by the square footage of the house. For cold regions, the calculated value for private houses is increased to 175 W, for multi-storey houses - to 101 W.
If it seems too time-consuming, we suggest using a calculator. By selecting the required positions and entering the missing data, you can obtain the desired value.
Circulation pump performance calculator
The circulation pump, which can be equipped with heating systems of both closed and open types, ensures constant movement of the coolant through the elements of such systems and, accordingly, increases the efficiency of their use. The main structural elements of any circulation pump, regardless of its type, are:
- housing made of corrosion-resistant metals and alloys;
- a drive electric motor, which consists of a stator winding and a rotor rotating in its internal part;
- wheel with blades - an impeller whose rotation axis is rigidly connected to the rotor shaft.
When power is supplied to the stator winding of the circulation pump (this is also what this pump is called), the rotor begins to rotate, transmitting torque to the impeller. When the impeller with blades rotates in the working chamber, a vacuum is created in the supply line, which facilitates the absorption of liquid from the pipeline through it. The liquid entering the working chamber is affected by the centrifugal force created by the rotation of the impeller, which leads to an increase in the coolant pressure in the chamber and its ejection under a certain pressure through the discharge pipe into the heating system circuit. Thanks to the flow pressure of the heated working medium created by the pump, the coolant circulates freely along the circuit of the heating system, overcoming the friction force.
By using a heating pump in a private home, you can warm up all the rooms of the building in a very short period of time and maintain a comfortable temperature in them, simply by adjusting the speed of operation of such a device.
Heating system with return pump
Moreover, pumps allow you to save energy resources, which are used to heat the coolant to a certain temperature. Practice shows that gas savings when using a circulation pump for heating are approximately 25–30%. Such significant savings are achieved due to the fact that the coolant, launched into the heating circuit using a circulation pump, quickly passes through the pipes and returns to the boiler while still quite warm.
It is clear that heating a coolant that has not yet cooled down to the required temperature requires less energy than when performing such a procedure with a cold liquid. Accordingly, the operation of a boiler that heats a still warm coolant fluid requires less fuel or electricity, which allows saving on their consumption.
Main varieties
All circulation pumps for heating systems are divided into two design types: devices with a “dry” rotor and circulation pumps with a “wet” rotor.
In circulation pumps of the first type, as is already clear from their name, the rotor does not come into contact with the liquid working medium - the coolant. The impeller of such pumps is separated from the rotor and stator by sealing steel rings, which are pressed against each other using a special spring that compensates for the wear of these elements. The tightness of this sealing unit during pump operation is ensured by a thin layer of water between the steel rings, formed due to the difference between the pressures in the heating system and in the external environment.
Circulation pumps for heating with a dry rotor are characterized by fairly high efficiency (89%) and productivity, but hydraulic machines of this type also have disadvantages, including loud noise during operation and difficulty in operation, maintenance and repair. As a rule, pumps of this type are equipped with heating systems for industrial purposes; they are used quite rarely in domestic heating systems.
Single-stage circulation pump with dry rotor
A circulation pump for heating systems, equipped with a “wet” type rotor, is a device whose impeller and rotor are in constant contact with the coolant. The working environment in which the rotor and impeller rotate acts as a lubricant and coolant. The stator and rotor of pumps of this type are insulated from each other using a special glass made of stainless steel. Such a glass, inside of which the rotor and impeller are located rotating in the coolant medium, protects the stator winding, which is under voltage, from contact with the working fluid.
The efficiency of pumps of this type is quite low and is only 55%, but the technical capabilities of such a device are quite sufficient to ensure the circulation of coolant in heating systems of houses that are not too large. If we talk about the advantages of circulation pumps with a “wet” rotor, then they include the minimum amount of noise produced during operation of such devices, high reliability, ease of operation, maintenance and repair.
Wet type circulation pump
A heating circulation pump will provide your comfort only if you correctly answer the question of how to choose such equipment. Correct selection of a circulation pump for a heating system requires a preliminary assessment of the following parameters of both the device itself and the elements of the heating system on which it is planned to be installed:
- pump performance, which characterizes how much liquid it is able to pump per unit time;
- the value of the created coolant pressure (this parameter characterizes the height to which the liquid can be raised using a circulation pump);
- the diameter of the pipeline on which the pump will be installed;
- temperature of the liquid circulating through the heating system;
- throughput and performance of the heating boiler.
In addition, choosing a circulation pump involves taking into account factors such as the volume of heated rooms, the air temperature in them, and the type of coolant.
The marking of circulation pumps allows you to determine the main installation and technical characteristics of pumping equipment. How to choose a circulation pump for heating based on markings? It is not difficult. For example, numbers 25–60 mean that the diameter of the pump pipes is 25 mm, and the pressure generated is 6 m of water. Art. (or 0.6 atm). These characteristics must be compared with the calculated parameters of the heating system and decide whether or not we choose such a pump.
When choosing a pump for a heating system, you need to pay special attention to such an important parameter of these devices as the liquid pressure that they are capable of creating. In this case, the total length of the heating circuit through which the coolant will circulate should be taken into account. Any specialist, having calculated the total length of the heating circuit, selects a circulation pump to equip it in such a way that for every 10 meters of pipeline there is approximately 0.6 m of water. Art. pressure created by pumping equipment. For heating systems, the total length of the circuits does not exceed eighty meters, one circular pump is sufficient. If the length of the heating circuit is longer, you can use several circulation pumps at once.
Before choosing a circulation pump for a heating system, you should also take into account the diameter of the pipes from which such a system is installed. It is necessary to pay attention to this parameter because pipes of smaller diameter are characterized by higher hydraulic resistance; therefore, in order for the coolant to circulate normally through such pipes, a pump with higher pressure characteristics is required.
How to choose a circulation pump for heating, focusing on the performance of such a device? The coolant flow that a specific circulation pump must provide is calculated quite simply: it is equated to the power of the heating boiler. For example, to equip heating systems served by a 25 kW boiler, you should choose a circulation pump with a capacity of 25 l/min. This simple rule makes the question of how to select a circulation pump for a heating system based on the performance of such a device easy even for non-professionals.
How to choose a heating pump in order to not only increase the efficiency of the home heating system, but also use energy (fuel for the boiler or electricity) more economically? To do this, pay attention to device models whose operating modes can be adjusted. Using adjustable circulation pumps, you can quickly warm up your home when it gets cold outside by simply running them at maximum speed. When a comfortable air temperature is established in the premises, the operation of the pumping equipment is switched to an economical mode.
Installation rules
The question of how to choose a pump to equip autonomous heating systems is important. However, the correct installation of such equipment is equally important. First of all, it is necessary to correctly select the area of the heating system on which the circulation pump will be installed. It should be remembered that the pump requires regular maintenance, so access to the equipment must be free.
The most suitable place for circulation pumps in heating systems of private houses is the section of the pipeline located directly in front of the entrance to the boiler (return). If you install a pump in the upper part of the heating equipment (on the supply line of the pipeline), then along with the coolant it will suck air out of the boiler, which will lead to the formation of a vacuum in the chamber of the heating device and boiling of the liquid in its airy space. If the circulation pump is installed on the pipeline before entering the boiler, it will not only minimize the risk of air locks in the pipes, but also operate at a lower coolant temperature, which will increase the service life of such a hydraulic machine.
Pumps for heating private houses must be installed in the pipeline so that the axis of their rotor shaft is in a horizontal plane. If you neglect this requirement, you may encounter not only the loss of a significant part of the power of the pumping equipment (up to 30%), but also the failure of the circulation pump due to insufficiently effective cooling of its moving parts.
In order to be able to use the heating system even if the circulation pump is not running in it, it is necessary to equip it with a bypass line - a bypass. If a bypass is used in the heating system, the coolant circulates naturally. A ball valve is mounted on the bypass (a section of pipe connected to the heating circuit, bypassing the circulation pump), and when it opens, the bypass line begins to operate. What diameter should the pipe from which the bypass is made have? It should be borne in mind that its cross-section should be smaller than the diameter of the heating pipes.
When studying a typical circuit for installing a circulation pump, a natural question arises about why such a circuit uses a filter installed on the suction line of the pumping equipment. The use of such a filter allows you to protect the pump from the entry of solid particles present in the coolant into its interior. Such particles, if not filtered, contribute to intense wear of the moving parts of the circulation pump and, accordingly, breakdowns.
Ball valves should be installed in the pipeline sections in front of the pump entrance and at its outlet, which, when dismantling the pump, will allow the water supply to be shut off only in the section of the pipeline where the hydraulic machine is installed. Instead of one of these ball valves, a check valve can be used, which is a better solution.
The use of a check valve located at the outlet of the circulation pump protects the latter from such a negative phenomenon as a reverse counterflow of coolant.
Most owners of private houses and summer cottages who are planning to equip their buildings with autonomous heating systems do not have any questions about why a circulation pump is needed, since it allows them to heat the premises more efficiently and economically.
Most heating systems operate fully with a circulation pump (in common parlance - a pump). The pump maintains the required liquid pressure in the heating circuit. This is its purpose - to maintain the required pressure in the system, helping to overcome the hydraulic resistance of circuit elements (pipes, radiators) to the coolant, additionally moving it along the circuit. There are systems with several pumps: one in the heating boiler and one or two in the heating circuit. If you have a well-functioning circulation pump, it is not at all necessary to place the heating boiler at the very bottom of the heating circuit.
Design and types of circulation pumps
Most pumps have the following design:
- Frame with attached snail
- Screwed to the snail circuit pipes
- Mounted in the housing electric motor with a control board and terminals for connecting power supply wires.
- Rotating part of the engine - rotor with nozzle(impeller) - moves water, sucking it in on one side and pumping it into the circuit pipes on the other side
The result of the work is some inlet vacuum pump and the required pressure (compression) at the outlet. All circulation pumps, depending on their design features, are classified into two types:
- “dry” type (with a dry rotor);
- “wet” type (with a wet rotor).
Dry-type pumps are characterized by the fact that their rotor itself does not come into contact with the working fluid of the circuit heating. It is reliably isolated from it by a sliding seal - a ring. Such pumps have a fairly high efficiency - up to 75-85%, but operate with a certain noise level. These pumps are larger in size than their “wet” counterparts and require special piping of the circuit. Moreover, they usually need periodic maintenance. As a rule, these pumps are used in individual boiler houses that provide heat to several buildings or an industrial enterprise.
In “wet” type pumps, the rotating rotor itself is in contact with the pumped fluid. coolant fluid, and the stationary part of the pump electric motor, the stator, is isolated from it. Interaction with the liquid ensures the necessary lubrication of the rotor parts and quiet operation of the entire pump as a whole.
Typically pumps have a built-in step speed controller. Wet-type circulation pumps can operate for years, and sometimes decades, without requiring any maintenance. But they have low efficiency - only 50−65%. Pumps of this type are most widespread in private household heating systems precisely because of their small size and quiet operation. These aspects are among a number of others when choosing a circulation pump for the heating circuit of your home. But there are other aspects to choosing a pump. We will consider them.
How to choose the right circulation pump?
A well-functioning pump in the heating system of a separate house or cottage must meet the following requirements.
Everything is clear with the last point. The smaller the pump and the quieter it operates, the better. From this point of view, circulation pumps are undoubtedly more suitable for installation in a heating system "wet" type. Let's look at other points.
Calculation of pump performance
The first three requirements for a pump are closely related and one depends on the other. Productivity means amount of liquid distilled, its consumption at minimum pump load. To put it simply, the higher it is, the better.
There is a famous formula its calculations: Q = N /(t 2- t 1)
- Q- consumption (productivity),
- N- power of the heating source (heating boiler),
- t1- temperature of the liquid in the return pipes of the heating circuit,
- t2- temperature in the supply part of the circuit, i.e. after the heating boiler.
When calculating, the t1 value is taken within the range of +60 ÷ +70С°, and the t2 value - +90 ÷ +95С°. This formula allows you to approximately select the parameters of the desired pump. It is generally accepted that for 10 meters of the length of the circulation ring of the circuit it is necessary approximately 0.6 meters of pump pressure.
There are already calculated thermal standards. It is considered: for warming up 10 sq. meters of room requires 1 kW of heating boiler power. If we take the thermal power of one section as 200 W, then per 10 sq. meters will require 5 sections. As a rule, it is taken small supply in the form of 1-2 sections. The pump must be able to supply water to all radiators in the building
Pump pressure
Pump pressure refers to the level to which the pump can raise water in the heating system. It is measured in meters of water column or atmospheres. Typically this value is indicated in the documentation for the pump and on the pump itself(special tag).
Consider the GRUNDFOS UPS 25−40 pump.
The manufacturer is quite well known. The number 40 indicates the height of the coolant rise - 4 meters. Which corresponds to 0.4 atm. pressure. It is by this value that you need to select a pump primarily for your system. What does the number 25 mean? It indicates the diameter of the connected pipes - 25 mm (1 inch). Typically, pipes with a diameter of 25 mm and 32 mm (1.25 inches) are used to connect the pump. Therefore it should look at the full name of the pump- it must match the diameter of the pipes (adapters) in your heating system. Typically, the pump also indicates the power consumption in different modes, the number of revolutions and the direction of movement of the rotor and coolant.
External factors influencing pump operation
And, of course, the operation of the pump is affected external conditions. The ambient temperature has a greater influence on the amount of heat needed to heat the room, and therefore on the operation of the pump. In some rare cases, it also affects the operation of the pump itself - a “frozen” pump does not work as well as a “warmed-up” one. By the way, the pump will begin to overheat if it is selected incorrectly - it may do not cope with excessive load. Therefore, when purchasing it, you should know the parameters of your heating system and boiler.
The larger the diameter of the pipes, the more water in the system, the more powerful the pump is needed. In addition, the coolant made from non-freezing liquid has a viscosity that is different from the viscosity of water, so the pump should be selected more productive and reliable. Fortunately, the choice of circulation pumps is quite large - you can choose the one you need for almost every heating system.
From the author: Of course, the pump must cope with the load. But you also need to take into account the fact whether it will work constantly, or turn on only at the required intervals. If you plan to turn on the circulation pump only to recharge the heating system and slightly adjust the pressure, it is not necessary to choose a powerful high-performance pump of the brand. The Wilo N.O. -25/4 pump installed in my basement (see photo) is turned on once every 3-5 months for 1-2 minutes to raise the pressure by 0.1-0.5 atm. But again: in the wall-mounted gas boiler I already have a built-in pump that runs constantly. Therefore, all factors should be taken into account.
If your pump operates in tandem with a natural circulation circuit, then the load on the pump may be high. In this case, the greater its productivity and pressure, the better. If the wrong choice is made, the pump may simply not cope with the task assigned to it - it will It’s bad to “push” the system, as a result the batteries will be barely warm. And the pump itself can overheat and burn out. Also, do not install a 1-inch pump into 1.25-inch pipes through adapters. In some cases, it will not be able to provide the required pressure.
Another parameter of the pump is its electrical power consumption. As a rule, it is small - from 50 to 200 watts. It is only of great importance when the pump is constantly on.
Is the brand of pump so important?
There are many types of pumps from different companies on sale. Almost all of them have the same characteristics. Differ mainly degree of reliability and service life.
The most common brands are Grundfos, Wilo, Wester, Wita, ELSOTHERM, Speroni. There are also a lot of different fakes from China or clearly Chinese products. The first two brands on the list are the most reliable. They are distinguished by excellent reliability and noiselessness. You can verify their operation by ear only in close proximity (5-10 cm) or by placing your hand on them. They work for years without requiring any attention. But they have one small drawback - high price. Their price is approximately 2 times higher than lesser-known brands.
Other brands are considered average in terms of price/quality ratio. They work quite well, problems with them are very rare. Their prices are in the average range.
Advice: With the right choice, the pump will work without straining. Accordingly, the heating system itself will be distinguished by reliable, full-fledged operation and there will be no interruptions in heat in your home.
Owners always agree on Chinese products: sooner or later these products begin to make noise, the rotor becomes loose, or the pumps simply burn out. They can work for a couple of months, or they can last a couple of years. The price for them, of course, small.
Which one should you choose? Let's say right away - never buy Chinese pumps. If you don’t mind overpaying for a brand, take Grundfos or Wilo. If you don’t want to overpay for the brand, buy a pump from the middle price category.
