E and Andreev scheme for finalizing the engine. Andreev's internal combustion engine power supply system. “Japan was punished for trying to introduce such technologies and exit from raw material monopolies”

For hot water supply, it acts as one of the important nodes of the system. Without this equipment, it will not be possible to achieve pressure, as well as water circulation in the wiring. Therefore, before purchasing this unit, it is necessary to take into account the nuances that affect the efficiency and purpose.

Description in terms of design features

Comparing several models of circulation pumps, you can understand that, first of all, they differ from each other in the type of rotor. On this basis, the described equipment can be classified into devices with:

• wet rotor;
• dry rotor.

In the first version, the support part, which assumes the presence of an impeller, is placed in the pumped medium. In this case, the hot coolant acts as a lubricant and coolant. Glandless pumps are almost silent during operation and are characterized by a long service life. They are cheap and require no maintenance. This indicates that such a circulation pump for hot water supply can be installed and forgotten about.

However, such units also have disadvantages, one of which is expressed in a low efficiency, it ranges from 40 to 45%. Among other things, the positioning of the pump is limited, because it can only be installed horizontally. Therefore, this equipment is purchased by those people who want to equip a heating and water supply system in a small house. After all, this unit is not capable of great accomplishments.

Description of dry rotor pump

The DHW circulation pump can also have a dry rotor, in which the power plant is separated from the pumped medium. The rotor remains dry during operation, which leads to problems with cooling and lubrication. The problem is solved by periodic inspection, as well as with the help of a fan.

Dry pumps are more expensive in the long run, both at the acquisition stage and at the maintenance stage. But these efforts will be rewarded with more impressive performance, which reaches 70%. Therefore, a similar circulation pump for domestic hot water can be purchased for installation in utility and industrial systems.

Main performance characteristics

The main task of the described equipment is to maintain the speed of the flow of water through the wiring. Therefore, the main criteria that affect the choice of pump are:

• pressure value;
• consumption;
• heat transfer.

The pressure parameters are determined by the height of the water column, the pressure and temperature on the return will depend on this. As for the flow, it is determined by the formula as the quotient of the power and the temperature difference in the processing and pressure pipe. Heat transfer is determined by the area of ​​the heated room and heat loss.

Description of the Wilo-Star-Z pump

When choosing a circulation pump for hot water, you can pay attention to the model mentioned above. It is a wet rotor unit that can be used to maintain pressure in water and heat networks. This model has mechanical shut-off valves and electronic stuffing.

As for the first component, it assumes the presence of a ball valve at the outlet and a check valve. The electronic component is:

• display;
• thermostat;
• timer.

This version of the pump can be used in conventional systems and high-tech networks that are built into the smart home system. for domestic hot water, it has a thermal disinfection recognition system, which is used when working with drinking water.

Characteristics VortexBW 152

This equipment is made in Germany, which means it is of high quality. The model is characterized by high performance and maintainability. You can disassemble the device quite simply, and the unit itself does not need to be dismantled. Without removing it from the pipe, the pump can be descaled. It works completely silently and differs from analogues in its modest size, therefore it is quite often used in everyday life.

Description of the pump ESPA RA1-S

This circulation pump for DHW systems is another representative of equipment with a wet rotor. It can be used for air conditioning and ventilation systems. The main difference from analogues is the possibility of vertical installation. It is possible to use the equipment in systems of supply of cold water and hot water supply. The device is capable of pumping heated flammable liquid, the temperature of which reaches 120°C. In everyday life, the device has proven itself positively, it is productive and economical.

Specifications Grundfos UP

The DHW circulation pump UP is equipment with a heat-insulating casing, the flow part of which is isolated from the stator by a shell. The engine has a wet rotor, which ensures almost silent operation. If necessary, the equipment can be disassembled without removing the housing from the pipeline. The unit does not require maintenance.

This Grundfos DHW circulation pump can operate in one of three speeds, has an electrical output of 25 W and an operating pressure of 10 bar. The temperature of the pumped medium can vary from 2 to 95°C. The recommended set is 0.93 m, while the connection is made with the following parameters Rp 1/2. The recommended feed is equivalent to 0.38 m 3 /h. The installation length is 80 m, the maximum pressure is 1.4 bar. The device weighs 2.6 kg, and the water protection class corresponds to the designation IP42.

Key features and benefits of Grundfos UP pumps

Before you buy UP, you should consider their distinctive features from their counterparts, they are:

• spherical rotor;
• low noise level;
• protection against lime deposits;
• long service life.

Consumers choose these devices also for the reason that their operation is accompanied by a slight consumption of electricity. High-quality materials are used in the manufacturing process, and any home master can install the device.

After installing such a pump, you can get hot water as soon as you open the tap. The presence of a spherical rotor almost eliminates the blocking of the impeller by lime deposits and impurities. The plug connector is reliable and simple, thanks to which the connection to the mains is greatly simplified, as is the operation.

Pumped media and operating limits for Grundfos circulation pumps

Before purchasing a circulation pump, it is important to consider the media being pumped. When it comes to Grundfos UP models, they are able to work with aggressive, non-viscous, clean liquids that do not contain solid particles and fibers. Such equipment is capable of working with water that has previously been softened. There are certain operational limitations, which are expressed in the maximum possible kinematic viscosity of water, it is 1 mm 2 /s, which is true for a temperature of 20°C.

Conclusion

Before choosing a circulation pump, it is necessary to take into account the expected pressure of water flowing from the tap. The maximum allowable value of this parameter is 4.5 bar, while the minimum is not regulated.

It is also necessary to take into account the number that can be opened at the same time. If a pressure of 5 bar is created in the pipeline, then when one tap is opened, the pressure will be higher than the permissible value, and the jet will damage the plumbing equipment.

The lack of hot water pressure when the tap is opened is a fairly common phenomenon that occurs in private and apartment buildings. One of the effective means of solving the problem is a circulation pump for hot water.

Installation of pumping equipment for hot water supply, according to existing building codes, is optional for rooms with a heated area of ​​​​up to 500 m², in practice, installation may be required even if there are 2-3 separate hot water points.

Why do you need a hot water pump

The DHW circulation pump is designed to create pressure and constant circulation of water in domestic water supply systems. After opening the tap, you have to wait a long time until the water becomes hot, and the farther from the DHW inlet the draw-off point is located, the more time is needed for this. The pressure in the system does not always meet even the minimum requirements, preventing you from washing normally.

DHW circulation pumps are installed for the following purposes:

• Ensure stable pressure in the system- for this, hot water is diverted into a special buffer tank, after which it is supplied under pressure to water supply points.
• Provide instant hot water- the circulation pump for hot water supply is connected to a closed pipeline. Water is constantly in motion. Due to circulation, the cooled liquid is mixed with the heated one. As a result, immediately after opening the tap, hot water is supplied to the consumer.

The parameters of domestic water supply make it necessary to install hot water in both private and multi-apartment buildings.

What is the difference between circulation pumps for heating and hot water

The use of a circulation pump in a hot water supply system has its own characteristics that differ from the use of stations in water heating circuits. For this reason, the circulation equipment for each system is not interchangeable.

The differences between circulation pumps are as follows:

• Performance- heating pumps have a larger power reserve, which is simply meaningless for domestic hot water. If necessary, you can put circulation equipment for heating systems on water, but not vice versa. Some manufacturers offer dual pumps with two electric motors specifically for this purpose. The module is simultaneously connected to DHW and heating.
• Case - another difference between models for heating, from pumps for domestic hot water, is the material of the case. In stations for hot water supply, the structure is made of brass, covered with a heat-insulating casing from above. Cast iron appliances are installed for heating.
• Heat carrier temperature. If you pay attention to the technical characteristics of the pumps, you will notice that DHW equipment can be operated at a liquid operating temperature of not more than 65 ° C. In heating systems, the coolant is heated up to 90-95°C.

Despite the external similarity, pumping equipment for heating and hot water systems is not interchangeable. The exception is "twin pumps" offered by many leading European manufacturers.

How does a circulation pump work in a hot water system

The principle of operation of the DHW circulation pump is almost identical to that used in heating systems. The purpose of the installation is to increase and stabilize the missing water supply pressure.

Circulation pumps in DHW systems of private residential buildings operate as follows:

• A closed DHW system is installed, consisting of: a storage tank, shut-off and control valves, pumping equipment and a circuit connected to water points.
• Hot water is drawn into the container. The pump creates the necessary pressure, forcing a certain amount of water to constantly circulate in the pipeline circuit.
• When the tap is opened, the consumer immediately receives hot water under pressure sufficient to take a shower, quickly take a bath, etc.

Most models of pumping equipment designed for the needs of hot water supply have electric motors based on a "wet rotor". All moving parts are completely submerged in water. The "wet" design has many advantages: no need for maintenance, quiet operation, low power consumption.

Along with this, there is a danger of dry running. The coolant plays the role of a lubricant. Without lubrication, bearings instantly fail.

Circulation pumps used in hot water systems of multi-storey residential buildings are often called booster pumps, since their task is mainly to create sufficient pressure for the water supply system.

How to choose a pump for a DHW system

Choosing a circulation pump for hot water can be difficult, even for a professional. During the selection, several factors are taken into account:

1. Technical characteristics of pumping equipment.
2. Additional functions.
3. Manufacturer's company.

The most convenient in operation are considered models with electronic control. The pump is supplied with a thermostat built into the housing. Automation independently examines the intensity of water consumption and, based on the results, selects the required operating mode. The on-off timer allows the module to autonomously switch to "night mode" to save energy.

The average life of the pump is 7-9 years. In practice, the station, under moderate loads, is guaranteed to work for at least 10 years.

How to calculate the pressure of the DHW pump

An accurate calculation of the pump parameters can only be made after obtaining the following data:

1. Loading of the water supply system.
2. Sufficient flow force.

The required pressure of the DHW circulation pump must be sufficient to create a comfortable pressure while turning on the taps at all draw-off points. How is the estimated pressure of hot water supply:

• The average water consumption for a point taken into account is 150-180 l / h. Accordingly, in a house with two bathrooms and a kitchen, you will need to install a pump with a capacity of at least 0.7 m³ / h. When calculating, it is necessary to take into account the hydraulic resistance of the DHW system, which for a private house is in the range of 0.1-0.2 atm.
• Head - the height and length of the water pipeline also affects the calculations. It is generally accepted that for 0.6 m of the water column, there are 10 linear meters of the water circuit. If the technical documentation of the pump contains head parameters of 4 m, this is enough for a water circuit with a length of 60 linear meters.

Such calculations help to obtain the average heat consumption of hot water through the circulation pump, which is enough to select the appropriate equipment for a small private house. Assistance in calculations and selection of a suitable model is provided by online calculators.

Calculations for the organization of hot water supply with a circulation pump in an apartment building and cottages of a large area should be carried out by a design and installation organization, which will be responsible for the system's performance.

Which companies produce pumping equipment for hot water

There are about a dozen different companies that manufacture pumping equipment specifically for hot water supply. The cost of the pump varies depending on the manufacturer and technical characteristics, from 5 to more than 100 thousand rubles. It is not recommended to purchase cheap modules, as often, a low-quality fake fails at a low cost.

The best manufacturers of hot water pumps are:

Domestic manufacturers focus on the production of equipment for heating systems.

Installing a circulation pump in a DHW system

The installation of the pump in the DHW system must be carried out in accordance with the manufacturer's recommendations and existing building codes. Installation work is carried out as follows:

• Place of installation of the DHW circulation pump - the module is mounted on the return line. This arrangement prevents air from entering the station - airing leads to a decrease in system performance. For this reason, the pump must be installed exclusively on the return line of the water supply.
• Immediately after the pump and in front of the storage tank, a check valve is installed. Be sure to install shut-off valves before and after the station.
• The electrical connection is made through the UPS for power. After a power outage, the uninterruptible power supply continues to provide autonomous operation of the equipment for several hours to a day. (how to choose the right UPS for pumping equipment,).
• To evenly distribute the pressure, a complex DHW control system is installed, including several distribution manifolds and special pressure reducing valves.
• It is forbidden to start the electric motor at idle. After the installation of the pump in the hot water system has been made, the water circuit is filled, a test run and a performance check are performed.
• Maintenance – Glandless pumps are simple in design and do not need to be inspected or repaired during their lifetime. The filter needs to be cleaned and replaced from time to time. The frequency of maintenance of the pump with a dry rotor, once every 2 years. During the work, the lubricant is replaced, the body is cleaned.

Insufficient pressure in the central water supply system necessitates the installation of a circulation pump for hot water in apartment buildings and private buildings, regardless of the heated area.

First of all, it must be remembered that circulation and booster pumps are completely different devices. The circulation pump does not change the static pressure of the system, but only ensures the movement of the coolant through the pipes.

The main characteristic of any circulation pump is the operating curve, which in the case of the DHW recirculation variant usually consists of a single curve, since it usually does not have switching speeds (Fig. 1). It can be seen from the graph that as the volume of the pumped liquid increases, the pressure drops. Conversely, with an increase in the height of the rise, the flow decreases. At the extreme point with the maximum pressure, the flow is zero, at the point with the maximum flow, the pressure is equal to zero.

The physical meaning of this curve is very conveniently illustrated by the example of an open system (Figs. 1 and 2). If the length of the pipe H is equal to H max, water will not flow out of it, since at this pressure value the flow V 0 is equal to zero. If you shorten the pipe to length H 1, water will flow out of it at a speed V 1. Removing the pipe altogether, we will get a flow at the outlet V max, since the pressure H 0 \u003d 0.

The situation described above is true only for open systems. In a closed system, the pressure created by the circulation pump is designed not to overcome the height of the liquid rise, but to compensate for pressure losses caused by the resistance of pipes and fittings.

Operating point of the DHW circuit

In a circulation circuit, pressure loss and volumetric flow are closely related. There is an equilibrium between the pressure loss in the system, which must be converted into a head loss, and the pump head. This means that the system losses are the same as the pump head at the duty point.

Since each value of the pump head corresponds to a single flow value, the volume of water circulating in the system is directly related to the resistance of pipelines and fittings. To determine the operating point, it is necessary to superimpose the curve of the DHW circuit on the curve of the circulation pump.

There are frequent cases when neither the curve of the system nor its operating point are known. In this case, the required pressure losses in the system and the required volume of hot water for circulation can be determined arithmetically by calculating the resistances of individual sections of the system.

At the same time, it should be borne in mind that it will be possible to achieve the design characteristics only if all circulation branches tied to one pump are hydraulically balanced using control valves, mechanical or thermostatic. The purpose of balancing is to maintain the optimum flow rate throughout the system, regardless of the length of the pipes and their diameter, in order to prevent an excessive drop in the temperature of the water returning to the boiler. Ideally, the difference between the supply pipe at the outlet and the recirculation line at the inlet to the water heater should be 2-3 K for small systems less than 200 m long and 7-10 K for large ones (more than 200 m in length).

In the standard case, with equal diameters of all circulation pipelines, in the branches located closer to the pump, the resistance must be increased to such an extent that it corresponds to the pressure loss in the distant branches. Away from the pump, on the contrary, it is required to create an increased flow so that the circulating water does not have time to cool down much.

The diameter of the circulation pipe depends on the diameter of the supply pipe. Unfortunately, the Russian SNiP 2.04.01-85 * “Internal water supply and sewerage”, unfortunately, does not have clear recommendations in this regard, so let's turn to the German DIN 1988, part 3 (Table 1).

Working point calculation

We now proceed to determine the operating point of the system. To do this, we need a flow V c and a pressure loss (head) Δp c . The flow that needs to be provided depends on the total volume of water circulating in all branches. To prevent excessive cooling of the liquid, the pump must provide such a speed that all the water in the pipes does not have time to cool too much. It should also be taken into account that the maximum speed should not exceed 0.5 m/s for copper pipes and 1 m/s for pipes made of other materials.

The pressure is determined by the sum of the resistances of the longest circulation branch, if we count from the connection of the circulation pipeline to the supply line to the inlet to the water heater. The operating point must be selected in such a way that the temperature of the hot water in the pipes does not fall below 55-60 ° C to prevent the growth of bacteria.

There are different calculation methods. We offer here one of them, quite simple, based on some averaged data. Among the disadvantages of this method, one can only note the possibility of its use for relatively small systems with a circulation pipe diameter in different sections from DN 10 to DN 20 and, accordingly, a pump flow area of ​​no more than 3/4ʺ.

First, we determine the heat loss in the pipelines. If there is no data from the manufacturer of pipes and thermal insulation, for a well-insulated pipe we accept: q tp.neot \u003d 11 W / s per 1 m of pipe laid in an unheated room (for example, a basement), as well as q tp.ot \u003d 7 W / s per 1 m of pipe laid in a heated room (for example, a plumbing box, kitchen, bathroom). The heat losses of fittings (valves, meters, etc.) can be ignored due to their insignificant influence on the overall result. Thus, the total heat loss in the system is:

Qtp = Σl tp.neot q tp.neot + Σl tp.ot q tp.ot, (1)

where Σl tp.neot and Σl tp.ot is the total length of pipelines laid in cold and heated rooms, respectively.

The maximum allowable temperature difference between the supply and circulation lines is taken equal to Δt tp = 2 K. Based on these data, we can now calculate the required flow rate:

where ρ is the density of water, equal to 1 kg/l; c is the specific heat capacity of water, equal to 1.2 W*h/(kg*K). So you can find the required water speed in individual branches.

If there is only one branch, then the flow in it is equal to the total flow. But this rarely happens, since the circulation line covers all draw-off points, therefore, it is replete with branches.

At the nodal points, the duct is divided into the main duct and the additional duct. The flow in the main part is equal to:

and in the extra:

or V add \u003d V c - V main. (five)

The pressure component of the working point is determined, as mentioned earlier, by the longest branch with a coefficient for bends and joints K = 1.2-1.4. The more winding the pipe, the greater the value of the coefficient should be taken. The channel in this case at each nodal point is divided into main and additional. If, after branching, none of the pipes goes directly to the draw-off point, the one in which the volume of water is less is considered additional. They also take into account the resistance of various fittings that are not included in the calculation of heat losses - valves, valves, etc.:

Δp c = KΣl tr R tr + ΣR arm. (6)

The pressure and flow calculated in this way represent the operating point of the system. Consider an example (Fig. 3). In table. 2 shows the main characteristics of the hot water supply system of a three-story building with five risers: the length of the metal-plastic pipelines laid in the basement and in the heated rooms, the inner diameter of the pipes, the type of flow when dividing at nodal points, and heat losses are calculated in each segment. After that, we find the common duct according to (2):

at Δt tp = 2 K.

Calculation of the required flow rate for each pipe section based on those determined in Table. 2 heat loss is given in table. 3. The heat losses of the main and additional sections are summarized in the column "Total heat losses", and the corresponding values ​​of the flow are calculated using formulas (3) and (4).

In table. 4, based on SP 41102-98, the speed of the coolant and the pressure loss due to friction are calculated (if the pipes are plastic or copper, then you need to use SP 40101-96 or SP 40108-2004, respectively). The longest branch: 10-8, 8-7 , 7-6, 6-1, the pressure loss in it is 1271.27 Pa. According to formula (6), we find the pressure at the working point:

Δp c \u003d KΣl tr R tr + ΣR arm \u003d 1.4 × 1271.27 + 200 \u003d 1979.78 Pa,

at K = 1.4 and R arm = 200 Pa. In terms of meters of pressure, 1979.78 Pa = 0.2 m.

According to the available in the table. 4 data, it is also necessary to adjust the control valves.

So, for this system, a pump with a duty point V c \u003d 189.17 l / h, Δp c \u003d 0.2 Pa is suitable. With such insignificant parameters, almost any of the DHW circulation pumps available on the market can easily cope.

1. Brochure VORTEX Brauchwasserpumpen. Technische Broschu..re. Trinkwasserzirkulation mit VORTEX Pumpen // 09de0090 11/09.

2. SP 41102-98. Design and installation of pipelines for heating systems of buildings using metal-polymer pipes.

3. SP 40101-96. Design and installation of pipelines made of polypropylene "random copolymer".

4. SP 40108-2004. Design and installation of pipelines for internal water supply and heating systems of buildings from copper pipes.

Hot water circulation in a residential building is not a luxury, but a necessity. That is why, for the efficiency of the entire system, it is better to purchase a circulation pump for hot water supply. It provides fluid circulation in a vicious circle. Without this unit, hot water from the tap would have to wait quite a long time, depending on the distance from the water heater to the tap. The cost of installing a circulating hot water supply is no more than the cost of a high-quality boiler of a popular brand. Those who want to choose a good circulation pump should know its features and nuances of choice.

A circulation (recirculation) unit for hot water supply is a device that ensures the movement of water in pipes. In addition, the equipment allows you to increase the pressure in the main pipeline to the desired level (the pressure should usually be higher by 1 kgf / cm² than the nominal one). Thanks to this device, on different floors of the house, hot water of the same set temperature can be obtained from the tap.

However, in addition to this, the device must provide a given pressure even during instant analysis during peak hours. Simply put, with several hot water taps open at the same time, the pressure and temperature of the liquid should be the same everywhere. Depending on the performance and design features of the pumping equipment, certain conditions are met, as well as automatic start and stop of the unit.

Such a pump is small in size, which simplifies its installation. The recirculation pump consumes a minimum amount of electricity. The device is installed in a pipeline break, while it can not be taken out of the general system and not used bypass.

Pumping equipment for hot water supply meets all standards. During daytime operation, the noise from the unit does not exceed 55 dB, and at night - 40 dB.

Principle of operation

The recirculation pump for DHW systems works according to the following principle:

• The heating equipment is connected to the main pipeline of a closed type, which runs through the entire house.
• Pipes of small diameter depart from the boiler. They go to the points of parsing.

Important: the circulation pump will save water, because with such equipment you do not need to wait until cold water runs out of the tap.

The unused circulating liquid is sent back to the heating boiler. To do this, a return pipeline must be connected to the boiler. From this we can conclude that the heater must have three nozzles:

• from the first branch pipe, hot water enters the water supply circuit;
• the second pipe is needed so that the liquid from the DHW circuit can flow into the tank;
• through the third branch pipe, cold water is supplied, replacing the consumed hot water.

Application area

The recirculation pump can be used not only for DHW systems. This pumping equipment is often used to solve other problems:

1. The device accelerates the circulation of liquid in traditional radiator heating systems.
2. Such pumping equipment is indispensable for the installation of heated floors. In this case, the unit is simply necessary, because in a narrow and extended piping system that heats the floor, significant efforts must be made to circulate the liquid.

Varieties

The recirculation pump for DHW systems can be of two types:

• reverse (installed on the return water supply pipeline);
• supply (attached to pipes through which hot water flows from the heater).

Attention: both types of recirculation pumps are used in closed circuit systems. The choice of one or another unit depends on your preferences or technical characteristics.

According to the design differences, all pumps for hot water supply systems are divided into two types:

1. Devices with a "wet" rotor. A recirculation pump of this type is distinguished by the fact that its pressure head (impellers and rotor) are located in the pumped liquid. In this case, hot water acts as a lubricant and a cooling medium. In this regard, this type of device is characterized by long and quiet operation. In addition, the "wet" device for hot water does not require maintenance and has an acceptable price. Among the disadvantages of this type of pumping equipment, it is worth listing the low efficiency (40-45%) and restrictions on installing the unit (the device can only be mounted in a horizontal position). That is why these units are bought by owners of small houses or summer cottages to organize domestic heating and water supply systems. These devices can raise the pressure in the system up to 1.5-3 atm.
2. Units with a "dry" rotor. In recirculation pumps with a dry rotor, the power plant is separated from the pumped medium. Since the rotor of the device constantly remains dry, it is necessary to solve the problems of cooling and lubricating the engine. To lubricate the unit, a periodic inspection is performed, and the engine is cooled by the built-in fan. That is why a “dry” parting for hot water supply is more expensive both when buying and when servicing. However, the performance of such units is twice as high as that of "wet" pumps, and can be 70%. Devices provide pressure increase up to 5-10 atm. The disadvantage is the high cost and increased noise level during operation.

Important: "dry" pumping equipment for hot water supply systems is purchased for the purpose of installation in industrial and municipal heating and water supply lines.

Depending on the ability to switch speeds, the following models of circulation pumps are distinguished:

• multi-speed- these units allow you to switch the operation algorithm. These are more expensive appliances used for heating and hot water systems in large houses;
• single-speed - these are models with reduced performance, suitable for domestic use. They easily fit into the system and work independently.

In addition, according to the design characteristics, single and paired devices for recirculation are distinguished. Both of these types of pumping equipment belong to the group of wet rotor pumps. Twin units are used when the power of a single pump is not enough.

Single unit has one motor and impeller. Twin models have two motors for higher pressure. In addition, in these devices, each engine can replace its fellow in the event of a breakdown. As a rule, industrial circulating units come with two engines.

How to choose pumping equipment for hot water supply according to performance characteristics?

The main task of the recirculation pump is to maintain the optimal speed of hot water in the pipeline, at which the temperature of the liquid in the return pipe will be within the required limits. In this regard, the choice of the unit should be made taking into account the following parameters:

• The limiting head of a liquid, measured in the height of the water column. This indicator affects the pressure in the pipes, and consequently, the temperature in the return pipeline.
• Fluid consumption. The required flow rate can be calculated using the formula. To do this, you need to find the temperature difference in the supply and return pipes. Then it is necessary to divide the power of the heating equipment by the resulting number.
• Heat transfer index of the heating system. This value is calculated depending on the area of ​​the heated room and the expected heat loss.

The recirculation pump is selected taking into account all the above parameters. It is important to compare the pressure of the pumping equipment with the flow rate of the heating system and heat transfer. This task is only possible for an experienced design engineer.

Popular Models

If you are going to buy a recirculation pump, then you should pay attention to the following models:

1. "Wet" pumping equipment Grundfos quiet operation and low performance. These are single-speed units that are suitable for installation in domestic heating systems. The advantages of such equipment are the almost complete absence of the risk of limescale formation on the internal surface, as well as the fact that the device does not require maintenance. It is equally important that the product can be dismantled without dismantling the pipeline.
2. The Wilo-Star-Z pump is another "wet" unit for domestic hot water and heating systems. This pumping equipment is equipped with shut-off valves: there is a ball valve at the inlet, and a check valve at the outlet. In addition, the model is notable for its electronics: there is a timer, display and thermostat. Also, the unit can work with a drinking water environment due to the fact that it is equipped with a system for determining the thermal disinfection of water.
3. Pump circulation equipment of the German company Vortex differs in high efficiency and maintainability. The pump can be quickly and easily dismantled without having to dismantle it. This allows you to clean the device from scale without removing it from the pipeline. Equally important advantages of the 152 R1 / 2 ″ model of this company are its compact size and silent operation, so the device is ideal for domestic needs.
4. ESPA RA1-S pumps are a wet unit, the main difference of which is the possibility of vertical installation. The device is suitable for domestic hot water systems and pipelines with cold water supply. The product is not suitable for solving production problems, since it cannot pump flammable liquids and water with a temperature above 120 ° C.