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To operate a modern heating system, equipped with forced movement of coolant along circuits, a circulation pump is used. It is thanks to this device that the coolant moves through the lines of the heating system, and the pump is also used in the heated floor system and the DHW recirculation system. Complex multi-circuit systems of large houses can be equipped with several circulation units.
To achieve effective heat transfer from a heating system, it is necessary that the parameters of the circulation pump correspond to the parameters of the system. To orient yourself on the topic of how to choose a circulation pump for a heating system, taking into account the heat source (boiler), you should familiarize yourself with the design and parameters of the pump.
Pump design and technical parameters
The design of the equipment includes a housing to which the volute is connected, and circuit pipes to the volute. The housing is equipped electric motor with board controls and terminals for connecting power cables. To move water along the system's main lines, a rotor with an impeller is used: with its help, water is sucked in on one side, and on the other side it is pumped into the pipes of the circuit.
The circulation pump should be selected based on the following technical parameters:
Classification
All pumps are divided into two types:
Dry rotor pump
The working part of the rotor does not have direct contact with water thanks to the protection of several sealing wheels. These parts are made from carbon agglomerate, high-quality steel or ceramics, aluminum oxide - it all depends on the type of coolant used.
The device is launched by the movement of the rings relative to each other. The surfaces of the parts are perfectly polished, in contact with each other, they create a thin layer of water film. As a result, a sealing connection is created. With the help of springs, the rings are pressed towards each other, due to which, as the parts wear out, they independently adjust to each other.
The service life of the rings is approximately three years, which is much longer than the life of the stuffing box, which requires periodic lubrication and cooling. The efficiency indicator is 80 percent. The main distinguishing feature of the unit is its high noise level, as a result of which a separate room is required for its installation.
Glandless rotor pump
The working part of the rotor - the impeller - is immersed in the coolant, which simultaneously acts as a lubricant and as an engine coolant. Using a sealed stainless steel cup installed between the stator and rotor, the electrical part of the engine is protected from moisture.
Typically, for rotor production ceramics is used, for bearings - graphite or ceramics, for the housing - cast iron, brass or bronze. The main feature of the unit is its low noise level, long period of use without maintenance, easy and simple settings and repairs.
The efficiency indicator is 50 percent. This is explained by the fact that sealing the metal sleeve, which separates the coolant and the stator, is impossible if the rotor diameter is large. However, for domestic needs, where coolant circulation is ensured in short-length pipelines, it is advisable to use such circulation pumps.
Composed of a modular design modern “wet” type devices include:
- Frame;
- Electric motor with stator;
- Box with terminal blocks;
- Working wheel;
- A cartouche consisting of a shaft with bearings and a rotor.
The modular assembly is convenient because at any time it is possible to replace a failed part of the circulation pump with a new part, and accumulated air can be easily removed from the cartouche.
How to choose a circulation pump for heating?
To select equipment taking into account the most suitable parameters, it is necessary use certain formulas. However, only specialists know which formulas need to be used in each specific case. And if the device is selected by an unknowing person, then you should use the following recommendations:
Circulation pump marking. For example, Grundfos UPS 25-50 equipment, where the first two digits indicate the thread diameter of the nuts - 25 millimeters (1 inch), which are supplied with the device. There are also pumps with nut diameters of 32 millimeters (1.25 inches). The second two digits are the maximum height of coolant rise in the heating system - 5 meters, that is, using a circulation pump, an excess pressure of no more than 0.5 atmospheres can be created. There are also pumps in which the lift height is 3, 4, 6 and 8 meters.- Unit performance. It is the main parameter that determines the operation of the unit. Represented by the volume of coolant pumped using a pump. The formula used for calculation is:
- Q=N:(t2-t1),
- where N is the power of the heat source. This could be a boiler or a gas water heater;
- t 1 – shows the temperature of the water in the return pipe. As a rule, it is +65-70 0 C;
- t 2 - shows the temperature of the water that is in the supply pipeline (coming out of the boiler or geyser). Often the boiler maintains +90-95 0 C.
- Calculation of the heating system and its losses is carried out in order to correctly select the design parameters of the unit that is able to cope with the resistance in the heating system.
- Heating system lift level. Shows the maximum pressure that the heating system is capable of. This is the total value of hydraulic resistance in the heating system. When calculating hydraulic resistance, the number of floors of a heated building with a closed heating system is not taken into account. In this case, the average value is taken - 2-4 meters of water column. In low-rise buildings with a traditional heating system, this figure is identical.
- Energy requirements of the building.
This is another parameter that is worth considering when choosing a circulation pump, albeit indirectly. This indicator is indicated in the building's passport during its design. If these values are missing, they can be calculated. Each country has its own heat standards per square meter. According to European standards, 100 W are required to heat 1 square meter of a one- or two-apartment building, and 70 W for an apartment building. The Russian standard is presented in SNiP 2.04.05-91. - Electricity consumption. Any heating circulation pump has three connection positions to the electrical network. All information regarding the electric current consumption of the pump is contained in the plate on the unit body (load parameters). Each switch position corresponds to a new pump performance, that is, the amount of coolant per hour pumped by the device through the heating system. The third position of the switch shows the maximum performance of this unit, and the maximum current consumption by the pump is indicated on the plate on the pump body.
Mass-produced equipment has average characteristics. Therefore, it is necessary to take into account the individuality of each heating system.
Note! A suitable pump should be selected taking into account the ability of the unit to operate in several modes, and its power should exceed the design power by 5-10 percent.
Conclusion
The pump should be selected taking into account its three main parameters - flow rate, connecting diameter and pressure height. It is worth noting that the characteristics obtained during the calculation are maximum pump performance. And since this mode will last a short time during the entire heating period by the boiler, it is necessary to select a pump with slightly lower performance. This approach will significantly save money and reduce energy costs.
The uninterrupted and safe operation of the heating system of a country cottage is one of the first and most important issues that must be resolved when designing engineering systems. Therefore, it is very important to know how to choose a circulation pump for heating a private house, what parameters need to be taken into account, and how to avoid pitfalls during operation.
When is a circulation pump needed?
The circulation pump provides a given rate of energy flow in an autonomous heating system (in a central system, this role is played by industrial units). The need for it arises already in the presence of one of the following factors:
wiring of 2 or more circuits;
route duration is more than 50 m;
at least with 1 level difference;
the presence of a complex circuit (warm floor system);
heating 2 or more floors;
installing a boiler in the basement;
in a heating system with free movement of energy when the temperature difference between the incoming flow and the return flow is more than 15-20 ºС;
when the temperature difference is more than 1-2 ºС in the radiators of one system.
The circulation pump in a short time creates the required speed of coolant movement in all circuits, ensuring uniform temperature distribution. The difference between the outlet and inlet temperatures, when installed correctly, should be about 10 ºС, which saves fuel and ensures careful operation of the boiler. The efficiency of the system increases by an average of 20-50%, which becomes noticeable both in stable room temperature and in saving money.
Principle of operation
Circulation pumps for heating private houses are a closed structure consisting of an electric motor and a working element - a flywheel or rotor.
Water enters the cavity (recess) of the pump, where it is given centrifugal motion by moving blades. Next, the water enters the spiral channel and, by inertia, with the already acquired speed, a spiral flow that reduces hydraulic resistance, flows further. At this point, a vacuum is created, into which a new portion of water is sucked in.
Pump modifications and technical parameters
Based on the design features, the pumps are characterized by the productive power of the engine, the type of rotor and control.
Engine
An accurate calculation of engine parameters is performed for a specific heating system, but the general selection rule is simple - power is proportional to the performance (size) of the working part.
Rotor or flywheel
There are 2 principles of rotor operation:
Dry. The rubbing parts and the rotor itself are located in a hermetically sealed housing - only the blades that create the flow come into contact with water. Such models are characterized by high power and efficiency, but are more sensitive to mechanical contamination of the energy carrier. It is required to undergo annual technical maintenance of the electric motor. In addition, their installation should be carried out away from living rooms due to the increased noise level.
Circulation pump with a dry rotor - the motor and supercharger are located in different housings Source m.2gis.ru
Wet. The most common type due to its ease of maintenance, cost and variety of models. In an open design, moving parts (bearings, shafts, rotor, etc.) are in water, which is both a lubricant for them and a coolant for the engine. Appropriate stainless alloys and gaskets made of waterproof materials are used. The system is less demanding of mechanical impurities in the energy carrier, and the service life of the household appliance is designed for 7 years.
In a glandless pump, the motor and blower are located in the same housing Source aquazoom.com.ua
Work management
Pump control is the choice of speed modes, on which the efficiency of the entire system depends. For heating, the minimum mode is used, while at low temperatures, rapid heat removal requires an increase in speed. To regulate this process, 2 types of control are used:
Mechanical. The speed selection is made independently, and switching is done manually. This control is effective for small circuits where the response to speed changes occurs quickly. Heating pump in a private house, most often, is purchased with such control due to its low cost and higher maintainability.
Smart upgraded models controlled by an automation system, which, depending on the temperature of the coolant, regulates the flow rate. They cost more, but when installing multi-component systems with collectors, they are indispensable. In addition, they increase energy efficiency by 25-35%.
Each manufacturer uses its own developments that promote trouble-free operation during the shelf life, so prices for models with the same characteristics differ, as well as the quality of the equipment.
The cost reduction in cheaper companies occurs due to the minimum safety margin. Most often, this means reducing the thickness of non-critical elements of parts, using less durable and cheaper materials, which are only sufficient for the specified service life. The choice of manufacturer largely determines the quality characteristics of the product. You can navigate them by reading reviews or delving into the study of the materials used for parts.
On our website you can find contacts of construction companies that offer house insulation services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.
What to consider when choosing
How to choose a circulation pump for the heating system of a private house, and what parameters you need to know for this. Since the pump is a power unit, the first selection criterion will be its power. Next, we determine the type of rotor, and lastly, the type of control.
To determine the power, you need to know the parameters of the heating system. For large objects: industrial, multi-story, measurements are taken. In private homes such accuracy is not needed, so it is enough to know:
Boiler performance. The calculation is made theoretically using the formula: W thermal boiler * K throughput (1l/min=60l/hour). For 25 kW 25*60= 1500 l/hour; for 40 kW 40*60= 2400 l/hour.
Pressure. Indicated in meters of water column. For this calculation, you need to measure the total length of the contour and multiply by a factor of 0.6 (10 linear meters correspond to 0.6 m w.s.). For the circuits of a one-story house, standard equipment of 6 m w.c. is sufficient, while 2 or more floors require the installation of a station or several pumps.
Rotor type. Affects cost and subsequent maintenance. Increased efficiency allows its use in complex systems. But taking into account the possibility of remote installation and regular maintenance.
Control. It also affects the cost of the unit itself, but convenience and efficiency more than make up for this drawback. In complex systems it is recommended to use only this type of control.
Pressure and air relief valve. It is not installed in all models, but you can overpay for this function, since it prevents the pump from turning on “dry” and ensures trouble-free shutdown during a power outage (the water heats up to a critical temperature, the pressure increases and the outlet valve opens).
Manufacturers
Pumps in this category, regardless of the company, must be replaced after the end of their service life, since there is a high probability of stopping due to sudden breakdowns. The units are divided by manufacturer, since each of them focuses on performance, cost and reliability, and the final characteristics of the pump differ.
European - as a rule, all work in the middle or high price segment and offer high quality. The price reduction is due to optimal design solutions and marketing policies, including the transfer of production to China.
The German manufacturer stands out for its high quality and efficiency Grundfos– these models are equipped with energy-saving technologies. The declared service life is at least 10 years.
Company Wilo also produces high-quality industrial and household models, mainly with electronic control.
DAB- Italy. With regular maintenance, the pumps work flawlessly. The company spends a lot of money to eliminate noise in dry-type pumps.
Chinese - in addition to the price, you should pay attention to the company.
The company's models have proven themselves well Oasis. First of all, this is the cost, which is 30% less than Russian and European analogues. At the same time, operation is guaranteed throughout the declared service life.
Russian ones, like other participants, work in accordance with European GOSTs and comply with all safety requirements.
Among Russian manufacturers, the most famous company is the Subline Service brand. UniPump. Manufactures pumps of various types. The models are characterized by their low cost and the use of the most efficient technologies.
Wester belongs to the company "Impulse". Produces products in a limited range. The pumps are distinguished by good assembly and the use of parts with a high margin of safety.
Company Gilex models " Master" And " Compass" The line includes pumps for small circuits and 2-3 storey systems.
Where to install the pump correctly
When installing pump for heating private houses, how to choose The location of installation is no less important an issue than the characteristics of the equipment itself. Here you need to take into account the operating principle of the unit, the type of system and the number of its circuits.
One of the options for connecting a circulation pump to the heating system Source akademy-heat.ru
The pump can be installed both at the inlet and outlet, providing convenient access to it for technical inspections and maintenance. In most cases, they prefer to install pumps at the inlet so that the pump pumps water at a lower temperature, but the main criterion is still ease of maintenance.
Video description
You can see the installation of supply or return pumps in the video:
Important! Installing a pump between radiators or in front of the expansion tank creates vortex flows that disrupt the direction of movement, creating temperature differences in different parts of the system. It is therefore very important that the pump is located between the boiler and:
radiator system;
collector;
expansion tank.
In a double-circuit system, with the connection of “warm floors”, a separate pump is installed for each circuit.
Installation of the system, which includes a circulation pump, is carried out with the connection of a backup power supply with a operating reserve of 4-6 hours.
For 1;-2-circuit systems, the installation of a bypass is mandatory, since in the event of a power outage it will ensure the natural movement of energy flow in the system.
For reference! A bypass is a bypass, a small section of pipe with shut-off or adjustable valves, sometimes with a check valve. It is built to bypass the circulation pump and, when it stops, ensures free flow movement.
The operation of the pump can only be checked when the system is full. The main indicator of correct installation is the uniform distribution of heat between all radiators.
Pumps with a wet rotor type are installed in a vertical position.
Installation of a coarse filter is required, and installation of a fine filter is desirable.
The pump must be located in a place accessible for maintenance.
After all the calculations, add 20% of the rated power, so you will ensure gentle operation of the equipment in the optimal mode of 85-90%, excluding operation at the limit of possibility.
Solid fuel boilers
This type requires separate consideration. When the electricity is turned off, the pump stops, but heating of the energy carrier in the boiler continues: it is impossible to quickly extinguish burning wood or coal, after 3-5 minutes the temperature will reach critical levels and the pressure relief valve will operate. If the pump is installed on the outlet pipe, the reset occurs after 4-6 minutes, while its installation on the return pipe increases this time to half an hour.
Video description
You can see the installation of a pump in a system with a solid fuel boiler in the following video:
Price factor
When choosing a circulation pump, the cost of the device itself and its efficiency in operation are important. As a rule, the operation of the pump is justified by savings on fuel consumption, and the cost of the model itself is determined by its performance. In Moscow, the price range for pumps is very large. Conventionally, they can be divided into 3 categories:
For 3.5-7 thousand rubles you can buy basic functions, with a minimum operating life and most often one-time use;
Devices costing 7.5-20 thousand are “workhorses” that accurately provide the declared characteristics, with a service life no less than that specified by the manufacturer and with several degrees of protection and an optimal safety margin;
VIP systems with full automation, a set of additional functions, a high safety margin and the ability to provide a large volume of heat will cost from 20 to 45 thousand rubles.
Video description
And some more thoughts about circulation pumps in the following video:
Advantages of a separate pumping unit
The use of pressure equipment is justified from the point of view of saving fuel and increasing boiler efficiency, which is why many companies integrate pumping units into boilers. But installing the unit separately has its advantages: quick replacement without removing the boiler, the ability to control the process in case of emergency situations (for example, using a bypass). In addition, the pump can be installed in a system not provided for by the project at the initial stage.
Conclusion
Despite the apparent simplicity of the choice, the parameters of the pump must be technically justified, for which mathematical calculations are carried out taking into account the laws of heat engineering, the individual characteristics of the system, therefore the exact choice must be made by a specialist who takes into account all factors based not only on theoretical knowledge, but also on practical experience.
The heating system is the most important communication in a modern home.
The climate in our country is such that it provides a comfortable temperature in the house for at least six months.
Therefore, it is necessary to carefully approach its design and performance.
Feasibility of use
In a small room, the heating system can operate by gravity. The density of hot water is lower, so water circulation occurs under the influence of gravity - all the cold water accumulates below, where it is heated by the boiler.
But in the case of a large apartment or private house, this method does not work well - the circulation speed decreases. Therefore, when the heating is turned on, the nearby radiators have time to fully warm up, while the distant ones are just starting to heat up.
At the same time, they will not be able to operate at full capacity, since the coolant will cool down before it has time to change.
To prevent this, the circulation speed is forcibly increased by setting . They allow you to significantly increase the speed of water flow in the pipes and achieve a timely change of coolant.
This allows you to increase the heat transfer of the heating system, since the time of movement from the boiler to the radiator will be significantly reduced, and the rate of heating of the room will increase. (By the way, you can read about installing circulation pumps in the heating system of a private house).
Technical criteria
Before you begin calculating the pump power, you need to clarify what criteria need to be taken into account:
- Area of premises. Abroad, when calculating a heating system, they use a value of 100 W per sq.m. That is, to heat a room of 20 square meters, you need 2 kW of heat per hour. In our country, the numbers are slightly different: 1-2 storey buildings are calculated at 173-177 W per kV. m.
- Temperature difference. The normal temperature difference between the entrance to the heating system and the exit is considered to be 20 degrees. That is, at the exit from the boiler and at the entrance to the system, for example, the water temperature is 80 degrees, and at the entrance to the boiler and at the exit from the system is 60 degrees.
- Density of water. The calculation is made in kilograms, and the pump parameter is usually in cubic m/h, so you need to know the density of water at 80 degrees - 971.8 kg/cub.m.
Power
Knowing all the initial data, you can safely calculate the required pump power using two formulas:
- G=(Q/1.16)*DT
- G=(3.6*Q)/(c*DT)
The first formula is used by foreign designers, the second by domestic ones. The letters indicate the following parameters:
Q is the amount of heat required. It is calculated based on the area of the heated room.
c – specific heat capacity. For water this value is 4.2 kJ/kg*C
DT – temperature difference at the inlet and outlet in degrees.
Thus, to heat a one-story building with an area of 70 sq. m., a pump with the following indicator is required:
G=(3.6*70*173)/(4.2*20)=519
Let's convert this to a cube. m/hour we get:
519/971.8=0.53 cubic meters m/hour
For stable and reliable operation of the pump, it is necessary to have a small power reserve. Typically this is 10-15%, which will ensure water circulation in case of a small amount of salt deposits at the proper level.
Therefore, the minimum pump rating for the house in our example should be 0.65 cubic meters. m/h.
Water speed
The second indicator that needs to be calculated is the water pressure or the speed at which it will flow.
To do this, it is necessary to divide the entire heating system into separate sections and calculate their resistance.
Depending on the configuration, they take the following values:
- Straight pipe. The resistance of 1 m is 0.01 – 0.015 Pa. Accordingly, we multiply the length of straight sections without any elements by this value and get the first term.
- Fittings and various fittings. These elements increase the required pressure by 30%. That is, the resistance value is within 0.013 – 0.02 Pa. We multiply this value by the number of fittings and get the second term.
- Each expansion valve increases resistance by 70 percent. The indicator will accordingly be 0.017 - 0.025 Pa. We multiply the number of temperature-controlled taps by the resistance and get the third term.
Marking of the circulation pump. (Click to enlarge)
After this, we sum up all the sections and get the final figure. For reliability, experts recommend increasing it by 20 - 30% to cover unaccounted factors. This is the value that should be given for normal water exchange in all areas of the heating system.
Thus, you only need to know two parameters: pressure and power. Knowing them, you can easily and simply select the appropriate model.
At the same time, if the choice is between a more powerful model, but expensive, and a less powerful, but cheap one, calmly take the cheap one. The calculation is made for peak loads that occur only a few times when the system is started; the rest of the time there is no such need.
How to install an additional pump in the heating system:
First of all, of course, the circulation pump must correspond to the characteristics of the boiler, which, in turn, are selected based on their heated area. Otherwise, if there is insufficient flow, the “extreme” batteries will be too cold.
The approximate formula for calculating the required performance is simple: Q = 0.86 x P/dt. Here P is the thermal power of the system, and dt is the temperature delta at the boiler outlet and return. That is, if we use a 40-kilowatt boiler and want to provide a delta of 20 degrees (usually this value is taken for normal operation), then in theory it will be enough for us to have a productivity of 1.72 cubic meters per minute. Then why did we list much more efficient pumps in the rating? Wait, that's not all.
During operation, the circulation pump must overcome the hydraulic resistance of the heating system. Please note that it is this that is important, and not the height of the system: the return balances the supply, that is, if the resistance was equal to zero, the pump would not actually be loaded with pumping. But in reality, pipes and radiators will always have resistance. A rough calculation for a two-pipe system gives the required lift height equal to the number of floors multiplied by a factor from 0.7 to 1.1; for a collector-beam system it increases to 1.16-1.85. That is, if we heat two floors with a “two-pipe”, and the boiler is in the basement, then the pump requires a lift height of about 3.3 m. Again, less than the pumps in the rating.
The fact is that volume height and pump performance are antagonists: increasing resistance inevitably limits performance. Therefore, each pump’s documentation contains a “height-performance” graph for each speed. So, the pump that suits us should have a graph such that the points of the required performance and lift height intersect approximately in the middle - such a “middle point” guarantees us that the pump will not be overloaded. This is especially important at the time of start-up, because the motor has to spin up immediately under load. Accordingly, the maximum performance and lift height figures for a properly selected pump will be higher than those obtained from the calculation.
Also keep in mind that glycol coolants have a higher viscosity compared to water, and the graphs are given specifically for water: you also need to make a reserve for this. In this case, the manufacturer must directly indicate in the pump characteristics the maximum concentration of propylene glycol in the coolant.
Finally, the pump itself must match the installation method(not everyone can work both horizontally and vertically), installation dimensions. Otherwise, the already assembled heating will have to be redone.
The use of a circulation pump for heating systems significantly improves their performance characteristics. In addition, such pumps, thanks to which the water heated by the boiler enters all elements of the heating systems much faster and less cold, allow you to save on energy resources (electricity, fuel for the boiler). The effectiveness of using circulation pumps as part of heating systems largely depends on the correct choice of such equipment, made on the basis of its technical characteristics.
Types and main characteristics
Before understanding the technical characteristics of circulation pumps for heating systems, you should become familiar with the different types of such equipment. According to their design, circulation pumps are divided into:
- with a “wet” rotor;
- with a “dry” rotor.
The design feature of devices of the first type is that the moving elements of their rotor assembly are constantly in contact with the pumped medium, which ensures not only their lubrication, but also effective cooling. In addition, the operation of such equipment, the rotor of which is constantly located in a liquid medium that perfectly absorbs all vibrations, is characterized by a minimal noise level. The advantages of circulation pumps with a “wet” rotor are also their compact size, ease of installation and maintenance. If we talk about the disadvantages of such hydraulic machines, the most significant of them is low efficiency.
Design of a circulation pump with a “wet” rotor
In circulation pumps with a “dry” rotor, as is clear from their name, the elements of the rotor assembly do not contact the liquid coolant, which gives such devices both advantages and disadvantages. The most significant advantages of hydraulic machines of this type are high productivity and efficiency, reaching up to 80%. Circulation pumps with a dry rotor are equipped with powerful thermal stations and heating systems for industrial use; as a rule, they are not used in domestic heating systems. Among the disadvantages of hydraulic machines with a “dry” rotor, they usually mention the rather high noise level, as well as the complexity of installation and maintenance.
Design of a circulation pump with a dry rotor
The technical capabilities and operating conditions of circulation pumps for heating systems are determined by a number of characteristics.
Performance
This parameter indicates the amount of liquid that the device is able to pump per unit of operating time. The unit of measurement for this parameter is m 3 /hour.
Pressure
Pressure is also called hydraulic resistance. The amount of pressure generated by the circulation pump is measured in meters or decimeters of water column.
Supply voltage
The type of electrical network (single- or three-phase) to which the pump can be connected depends on this parameter. Naturally, for installation in heating systems of residential buildings, you should choose hydraulic machines operating from an electrical power supply with a voltage of 220 V.
Power consumption
This characteristic depends both on the specific model of pumping equipment and on the mode in which it operates. Many models of circulation pumps designed for domestic heating systems can provide several speeds of pumping water. On the body of such pumps, as a rule, there is a special plate on which the power consumption and current strength corresponding to each operating mode are indicated. The vast majority of circulation pumps for domestic heating systems are characterized by power consumption in the range of 50–70 W.
Table 1. Main parameters and features of choosing circulation pumps for heating
Maximum coolant temperature
When choosing a circulation pump for a heating system according to this parameter, you should give preference to models designed to work with a working environment whose temperature can reach up to 110°.
Dimensions
This includes such characteristics as the diameter of the threaded part of the mounting elements of pumping equipment and the installation length of its body. Most of the circulation pumps used in domestic heating systems are simply cut into the pipeline and connected to its elements using union nuts - “American women”. Quite often, both the nuts themselves and the pipes for connecting the device to the pipeline system are already included in its factory configuration. The most common mounting diameters of circulation pumps used to equip domestic heating systems are 1 and 1.25 inches (25 and 32 mm, respectively). The installation length of household circulation pumps can be 130 or 180 mm.
Electrical protection class
Most modern models of circulation pumps for domestic heating systems according to the international classification correspond to IP44 protection class. Manufacturers provide pumping equipment of this class with protection against the entry of solid foreign particles larger than 1 mm into its interior. This is indicated by the first number 4 in the marking. The next number 4 in the designation of the protection class means that the electrical part of the equipment is insured against liquid drops and splashes flying at any angle.
Maximum fluid outlet pressure
On the housing of many models of circulation pumps you can find information about this characteristic. As a rule, for household equipment this parameter does not exceed 10 bar. From a practical point of view, it doesn’t mean anything; characteristics such as pressure and productivity are much more important.
Brand and manufacturing company
When choosing circulation pumps for heating systems (as well as any other technical devices), it is better to give preference to products from well-known manufacturers who take quality issues more seriously and provide reliable guarantees.
Technical characteristics of circulation pumps for heating systems are usually included in the designation of their models. Using such designations, in particular, you can immediately determine the following parameters: the liquid pressure created by the device, the diameters of its suction and discharge pipes, and the installation length.
Rules and features of choice
You should start choosing a specific circulation pump model only after the heating system has been designed and the total length of its closed circuit is known. In addition to the length of the heating system circuit, the choice of a circulation pump is also influenced by the number of radiators with which it will be equipped. Only after receiving all this data can it be determined with high accuracy what performance the circulation pump should have and what magnitude of coolant pressure in the system it should provide. It is very important to calculate the performance of a circulation pump for a heating system based on the lowest temperature outside, when the pumping device will operate at maximum load.
