Calculation of a circulation pump for heating - pump power

The heating system in a private house, as a rule, comes in two types - with natural and forced circulation. If in the first case water moves due to thermal expansion, then during forced circulation the coolant is pushed into the pipeline by the impellers of electric pumps, and for efficient operation, the correct selection of a circulation pump for the heating system is important.

The task of selecting a suitable model includes choosing its operating principle and calculating the main parameters - the volume of pumped coolant and pressure (supply height). You can carry out the necessary calculations yourself using formulas, tables or online calculators - for this you need to know what initial data to enter and how to make the calculations correctly.

Fig. 1 Circulation pumps for a private house in operation

Electricity consumption

You can often hear that a pump consumes a lot, but how much does it really mean?
Circular pumps do not lift water from the depths, but simply ensure its movement in a closed system. For this reason, the devices provide high performance with low power, usually sixty to one hundred watts. This is approximately the same as a regular incandescent lamp.

The power consumption of the pump and its size depend on many parameters. You can find energy-saving models with electronic filling. They are equipped with electronic frequency control and belong to the A-class. The devices are capable of automatically adjusting power in case of network parameters deviation. Despite their higher cost, the device pays for itself very quickly.

Before we find out how many kW we are consuming and calculate the electricity consumption of the pump, it is necessary to obtain information about the thermal power of the device. The following indicators are accepted:

• small private house - one hundred kilowatts (0.1 kilowatts) per square meter;
• apartment in a multi-storey building - seventy watts per square meter;
• industrial premises - from thirty to fifty watts per square meter.

It is necessary to independently calculate the required thermal power, taking into account the purpose and degree of thermal insulation. There are many convenient and understandable tables available on the Internet.

It is difficult to calculate how much electricity a pump consumes. Many aspects are taken into account. In an hour, a conventional pump consumes about four watts; in a day, the device consumes from forty to eighty watts. Indicators may increase or decrease depending on the weather, the degree of insulation of the room, and the intensity of use.

You can choose the right pump taking into account the following parameters: performance, pressure, design, operating efficiency. If you are at a loss as to which device to choose, seek help from a specialist.

Number of pump speeds

Well-known manufacturers of pumping equipment for heating equip their units with shaft rotation speed switches; in some models, the speed of the device is automatically adjusted. During operation, this creates additional convenience: since heating the liquid takes quite a long time, to quickly warm up the premises, you can set the maximum speed of the electric pump or save energy by setting the minimum speed of the electric motor when the room is heated.

The number of speeds, depending on the manufacturer, can be from 2 to 4 - the more there are, the more effectively you can use the circular in the heating system, and the most economical option is electronic speed control.

Fig. 13 Selection of electric pump according to pressure characteristics

Calculation of system hydraulic resistance

A calculation based on the power of the boiler may not be enough, because the system differs from system to system in length, pipe diameter, the presence of turns, the number of radiators and fittings - and these are all obstacles in the flow path.
Knowing the hydraulic resistance is important in order to determine the required pressure. Pressure is an indicator of the height to which a given pump can theoretically raise a column of water

Reflects the pump's ability to overcome system resistance

Pressure is an indicator of the height to which a given pump can theoretically raise a column of water. Reflects the pump's ability to overcome system resistance.

It is possible to calculate the exact pressure at home only if you have access to technical literature. The exact calculation formula is:

H = (R * L + Z) : p * V

• H is the required value (pressure).
• R – resistance of the straight section (100 – 150 – obtained experimentally).
• L – total length of pipes.
• Z – tabular data. Resistance of each fitting and fixture.
• P – coolant density.
• V – coolant movement speed.

And for approximate calculations you will only need to measure the total length of the pipes and estimate the amount of fittings.

For every 10 m of pipes you will need 0.6 m of pump pressure (supply and return are measured, rounded to the nearest ten and the resulting figure is multiplied by 0.6).

20–70% is added to the result (the minimum figure for simple systems, the maximum for those overloaded with reinforcement).

For reference:

• A three-way mixer takes up 20% of the speed;
• Fitting – 30%;
• Thermal relay – 70%.

Prevention and Maintenance

Long service life and trouble-free operation are possible only if proper operating conditions and regular maintenance of the pump are observed. Maintenance means periodic inspection and cleaning of the pump. Inspection for abnormalities in operation should be carried out at least once a quarter, that is, twice during the heating season. It is advisable to perform cleaning every two to three years, depending on the quality of the water and the conditions in which the pump operates.

During the entire period of operation, it is advisable to periodically check the operation of the pump:

• Connections are checked for leaks. If identified, gaskets and seals (tow, FUM tape, etc.) are replaced.
• The presence and condition of grounding is visually checked.
• The sound of a running engine should not be accompanied by clangs, knocks, or extraneous sounds.
• The engine should not vibrate much.
• The pressure in the line is checked and its compliance with the nominal one.
• The housing must be clean and dry. If this is not the case, then you should carry out external cleaning, check the electronic unit for flooding and eliminate the reason why the pump is wet.

Approximately every two to three years, it is advisable to clean the pump, including all its elements. This only applies to models that can be disassembled. There are pumps with a pressed or solid, welded casing that does not require repair or disassembly. Such units fail and are then replaced with a new assembly. It is advisable to entrust this work to a service center. However, if you have the skills and tools, you can do everything yourself

Required:

• hex wrench;
• slotted screwdriver (flat) 4 and 8 mm;
• Phillips screwdriver.

Before disassembling the pump, drain the water from the system or drain a separate area in which the pump is involved, dismantle it and then begin disassembly.

Procedure:

1. Using a hex wrench or Phillips screwdriver, unscrew 4-6 bolts around the perimeter of the engine housing at the junction with the shell of the pump part.
2. Remove the shell, leaving the impeller on the rotor shaft along with the engine.
3. Locate four drainage holes around the perimeter. Using a narrow slotted screwdriver, pry the jacket of the engine compartment under the impeller little by little around the perimeter. As a result, the shaft with the rotor and impeller will come out of the grooves and stator shell. You can help yourself by unscrewing the protective plug on the outside of the pump, inserting a screwdriver into the slot at the end of the shaft and lightly knocking the shaft out of the support bearing.

The analysis is now complete. Now you should clean the surface of the rotor, impeller and the inner surface of the shell from plaque and scale, if any, without damaging the surface of the parts. It is not permissible to use a coarse abrasive. It is better to use a brush with hard polymer bristles. Cleaning products containing a weak solution of hydrochloric acid can help. As a last resort, the finest sandpaper is used - “zero”.

For wet rotor pumps, it is important to check the cleanliness of the channel inside the shaft and the drainage holes located in the protective jacket separating the area of ​​the pump part and the motor. The fluid enters the rotor precisely through these holes and then returns through the internal channel; if they are clogged, engine cooling suffers.

For pumps with a dry rotor, waterproofing the support bearing is important. If a leak is detected from the pump block to the stator block, then all gaskets and seals inside the device should be completely replaced.

The condition of the bearings on which the shaft rests is checked. If they are already quite broken, they will need to be replaced, which is extremely difficult to do at home; you will have to contact a service center.

All seals and gaskets inside the pump should be checked for wear and replaced with new ones if necessary. Once all elements have been cleaned and checked, reassembly is carried out in reverse order.

Circulation pump needs cleaning

Correct calculation of the coolant in the heating system

Based on a set of characteristics, the undisputed leader among coolants is ordinary water. It is best to use distilled water, although boiled or chemically treated water is also suitable - to precipitate the salts and oxygen dissolved in the water.

However, if there is a possibility that the temperature in a room with a heating system will drop below zero for some time, then water will not be suitable as a coolant. If it freezes, then with an increase in volume there is a high probability of irreversible damage to the heating system. In such cases, a coolant based on antifreeze is used.

Types of open heating schemes

In an open heating system, the coolant moves in two different ways. The first option is natural or gravitational circulation, the second is forced or artificial stimulation from a pump. The choice of scheme depends on the number of floors and area of ​​the building, as well as on the expected thermal conditions.

Natural circulation in heating

The gravitational system does not have any mechanism to ensure the movement of the coolant. The process is carried out solely by the expansion of hot water. For the operation of the circuit, an accelerating riser is provided, the height of which is at least 3.5 m.

If you neglect to install a vertical transit riser, then there is a high probability that the coolant coming from the boiler will not develop a sufficient speed

The natural circulation heating system is optimal for buildings with an area of ​​up to 60 square meters. m. The maximum length of the circuit capable of providing heat is considered to be a 30 m mainline. An important factor is the height of the building and the number of storeys of the house, which allows the installation of an accelerating riser. The natural circulation scheme is not suitable for low-temperature applications. Insufficient expansion of the coolant will not create the proper pressure in the system.

Possibilities of the gravity circuit:

1. Connection to heated floors. A circulation pump is mounted on the water circuit leading to the floor. The rest of the system operates as usual. If the power goes out, the house will continue to be heated.
2. Working with a boiler. The heating device is mounted at the top of the system - slightly below the expansion tank.

To ensure uninterrupted operation, a pump can be installed on the boiler. Then the heat supply and hot water production scheme automatically becomes a forced option. Additionally, a check valve is installed to prevent recirculation of the coolant.

Forced system with pump

In order to increase the speed of the coolant and reduce the time for heating the room, a pump is built in. The movement of water flow increases to 0.3-0.7 m/s. The intensity of heat transfer increases, and the branches of the main heat up evenly.

Pumping circuits are constructed of both open and closed types. In open circuits, the expansion tank is installed at the highest point of the system. The presence of the pump allows you to increase the pipeline between the heating boiler and the batteries, both in height and in length (+)

1. The circuit with a built-in pump is volatile. To ensure that the heating of the room does not stop during a power outage, the pumping equipment is placed on the bypass.
2. The pump is installed in front of the boiler inlet on the return pipe. The distance to the boiler is 1.5 m.
3. When installing the pump, the direction of water movement is taken into account.

Two shut-off valves and a bypass elbow with a circulation pump are mounted on the return line. If there is current in the network, the taps close - the coolant moves through the pump. If there is no voltage, then the valves must be opened - the system will switch to natural circulation.

A check valve must be installed on the supply pipeline. The element is placed immediately after the boiler and prevents recirculation of the coolant during pump operation

The role of the pump in the heating system

The coolant can be moved through pipes in two ways. The first of them is called natural, that is, without the use of any additional interventions. The liquid moves due to the difference in density of cold and hot water. Ordinary gravity also plays a role - when installing a natural heating system, the pipes are located slightly at an incline.

The problem is that the coolant flow with this approach is quite slow due to the low pressure. The result is clearly uneven heating of the rooms in the house - the further the room is from the heating boiler, the colder it will be. And the larger the house, the more significant this difference will be. After all, while the coolant slowly flows through the pipes, it has time to cool down.

This is why natural circulation is only good for small apartments and houses. The length of the circuit with this approach is limited, as is the number of radiators, for the reasons described above. For a large house, this is not at all an option, since most of its rooms will remain cold, and there is nothing to say about the rooms located on the second floor.

This is where the circulation pump comes to the rescue. It is a motor with a rotor that is lowered into the coolant and rotates there, creating the required level of pressure and forcing water or antifreeze to move at the required speed.

A separate advantage is the ability to control the operation of the heating system. As a rule, the circulation pump has several power modes, with which you can vary the speed and strength of heating the house if necessary. For example, if the home is not permanent, but seasonal, and the owners have returned to it after a long absence, you can first set the pump power to maximum and quickly get a warm, comfortable atmosphere. And then reduce the pressure in the system and, accordingly, the heating intensity.

Possible causes of problems

If during your next preventive inspection you find that the circulation pump is working “somehow wrong,” then this is a reason to carry out a more in-depth check using some specialized tools. The most common problems are: lack of rotation of the rotor, overheating of the pump and poor coolant current. Each of them may have several reasons. Let's take a closer look at each possible malfunction:

• no rotor rotation when the pump is connected to the network. As a rule, this indicates some kind of failure in the delivery of power to the equipment. First of all, you need to inspect all the elements directly responsible for this function: electrical wire, device switch, etc. If you find any defect - for example, even the slightest insulation violation - you must immediately replace the damaged part with a new one. Until the defect is eliminated, the device cannot be used, as this is fraught with short circuits and other troubles. After checking the external elements, inspect the plastic fuse. With frequent voltage drops in the electrical network, it begins to melt and constantly opens the circuit. If you see that it is already openly deformed, it needs to be replaced. The next element that needs to be checked is the winding of the electric motor. To do this, you will need a multimeter, which can be used to measure the resistance level. In normal winding conditions, the indicator can vary from 10 to 15 Ohms or from 35 to 40 Ohms, depending on the specific rotor model. If the multimeter gives infinity or a value close to zero, then this indicates the need to replace the winding,
• pump overheating. This usually happens in cases where the circulation equipment for some reason is forced to work under increased load. Detecting overheating is quite simple - if the pump is hotter than the pipe, then this clearly indicates a problem. In the case when this happens with newly installed new equipment, it makes sense to check the correctness of the installation. Incorrect placement of the device may cause it to malfunction. If you find any shortcomings, you need to re-perform the installation procedures, making the appropriate adjustments. Another common cause of overheating is clogging of structural elements with dirt. Rust and scale play a big role in this. They form in some parts of the pipeline, and then fall off piece by piece and go along with the coolant, clogging all the equipment where they fall. This happens with the circulation pump. The presence of foreign particles inside the structure narrows the path along which the coolant flows. Thus, the pump has to apply more force to move the liquid. That's why overheating occurs. The solution to the problem in this case is to clean the clogged elements. The third reason for overheating has already been mentioned above - it could be an insufficient amount of lubricant on the bearings located inside the pump. The fourth reason may be too low - below 220 V - the voltage in the network. You need to check this indicator with a voltmeter and, if problems are found, correct them,
• poor coolant current. This refers to situations where the fluid circulates at insufficient speed. The reason for this may be an incorrect connection if your home uses a 380 V network. Check that the electrical wire is connected to the phase correctly - it is quite possible that it needs to be connected to another. The second reason for poor current may be the same clogging of internal structural elements mentioned above. This can be solved by cleaning the elements.

A few additional tips

Longevity is largely influenced by the materials from which the main parts are made. Preference should be given to pumps made of stainless steel, bronze and brass. Pay attention to what pressure in the system the device is designed for.

Although, as a rule, there are no difficulties with this (10 atm is a good indicator). It is better to install the pump where the temperature is minimal - before entering the boiler. It is important to install a filter at the entrance. It is advisable to position the pump so that it “sucks” water from the expander. This means that the order in the direction of water movement will be as follows: expansion tank, pump, boiler.

Conclusion

You should not strive to comprehend complex engineering mathematics.

At home, an approximate calculation will be enough. All resulting fractional numbers are rounded up.

Selection by size

You've probably noticed that the range of companies includes units with the same characteristics, but different dimensions and pipe sizes. How to select external pump parameters:

1. For installation on pipelines, bypasses and mixing units of underfloor heating, standard blowers with a length of 180 mm are used. “Shorty” 130 mm are installed inside heat generators or on highways in very limited space.
2. The diameter of the connecting pipes is selected to match the cross-section of the main pipeline. Increasing the standard size is permissible, but decreasing it is strictly not recommended. That is, a unit with 32 mm fittings can be installed on a DN 25 pipeline.
3. Pumps with Ø32 mm nozzles are used on primary rings and boiler circuits, as well as in modernized gravity systems.

The performance characteristics of the pumps do not depend on their installation length - 130 or 180 mm

Note. The dimensions of ready-made bypasses sold in stores are adjusted to fit a standard pump with an installation length of 18 cm.

The number of supercharger speeds does not play a special role. At home, 3 modes are quite enough, the optimal speed is the second. The air from the units is bleed through the side screw, so you should not buy products with a separate air vent.

Operating principle and purpose of the pump

The main problem for residents of the top floors of apartment buildings and owners of country cottages is cold radiators. In the first case, the coolant simply does not reach their home, and in the second, the furthest sections of the pipeline are not heated. And all this is due to insufficient pressure.

When should a pump be used?

The only correct solution in a situation with insufficient pressure would be to modernize the heating system with coolant circulating under the influence of gravity. Installing a pump will help here. The basic schemes for organizing heating with pump circulation are discussed here.

This option will also be effective for owners of private houses, allowing them to significantly reduce heating costs. A significant advantage of such circulation equipment is the ability to change the speed of the coolant. The main thing is not to exceed the maximum permissible readings for the diameter of the pipes of your heating system in order to avoid excessive noise during operation of the unit.

Thus, for living rooms with a nominal pipe diameter of 20 mm or more, the speed is 1 m/s. If you set this parameter to the highest value, you can warm up the house in the shortest possible time, which is important when the owners were away and the building had time to cool down. This will allow you to get the maximum amount of heat with minimal time.

The pump is an important element of the home heating system. It helps improve its efficiency and reduce fuel consumption

Operating principle of the device

The circulation unit operates using an electric motor. It takes heated water from one side and pushes it into the pipeline on the other. And from this side a new portion arrives again and everything repeats.

It is due to centrifugal force that the coolant moves through the pipes of the heating system. The process of operating a pump is a bit like the operation of a fan, only it circulates not air around the room, but coolant through a pipeline.

The body of the device is necessarily made of corrosion-resistant materials, and ceramics are usually used to make the shaft, rotor and wheel with blades.

Circular pump device

In the domestic water supply, the leading place is occupied by electric pumps of the centrifugal principle of operation - during intake, the liquid enters the centrifugal wheel through the inlet located in the center of its axis and is pushed out through the side outlet pipe.

In circular machines, the coolant enters the working chamber through the central hole, and then is pushed out by the blades of the centrifugal wheel through the outlet pipe located in the side of its body. Thus, according to the principle of operation, circulation devices can be classified as centrifugal types, having an efficiency coefficient of no more than 80% and sensitive to solid impurities in water.

Structurally, the electric pump consists of a housing, inside which is placed a moisture-protected electric motor with an impeller on the shaft; generally, the wheels of closed-type pumps consist of two disks, between which feed blades are placed.

Rice. 3 Option for installing the pump in a single-pipe circuit with heated floors

Installation recommendations for all types of systems

There are recommendations for installing all types of pumps:

• 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.

Manufacturers usually illustrate how to install the pump correctly Source as-elit.ru

• 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.

Important points to remember

I would like to repeat once again that all circulation pumps offered today are divided into models with a “dry” and “wet” rotor , as well as devices equipped with an automatic or manual speed selection system.

According to experts, the best choice would be devices in which the entire rotor is in the water. Moreover, such a choice is associated not only with the problem of discomfort that may arise due to increased noise levels.

It should be borne in mind that such pumps overcome the load arising in the heating system much more efficiently. During the installation of such pumping equipment, it must be taken into account that the rotor shaft must be placed in a horizontal position . If we talk about high-quality pump models, then high-strength steel is used for their manufacture, complemented by a ceramic shaft and bearings.

Most often, such equipment can last at least 20 years. But it is best to avoid using a unit equipped with a cast iron body as part of a hot water supply system. The fact is that it will not be able to withstand such working conditions and will soon begin to collapse. The most attractive option is models made of stainless steel, brass or bronze.

It happens that at a certain moment the pump begins to make noise. But this can also be observed with working equipment. Most often, this occurs due to the presence of air in the heating system. To solve this problem, air should be removed from the system using special valves. Next, you need to let the system run for a few minutes, and then perform this procedure again. Finally, you need to configure the pump.

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;

Comparison of characteristics of pumps in the economy segment Source ms.decorexpro.com

• 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.

What to look for when choosing a pump?

The selection of a pump for autonomous heating should be done based on the hydraulic characteristics of the heating system of a country house. Therefore, before visiting the store, you will have to calculate the optimal amount of heat that will be required to maintain a comfortable temperature in the rooms.

Additional information that you need to familiarize yourself with will help you correctly perform hydraulic calculations. Or you can take the advice of a competent specialist.

The optimal amount of heat for a particular object is influenced by many factors:

• material used for the construction and insulation of walls;
• climatic conditions;
• features of ceilings and floors;
• presence of thermostatic valves;
• characteristics of double-glazed windows installed in the cottage.

When choosing a pump for autonomous heating, special attention should be paid to the scope of application of a particular model, the number of speeds and noise level. The manufacturer and price of the equipment also play an important role.

When choosing a device for organizing forced circulation in a heating system, you need to pay special attention to the technical characteristics in order to avoid running the pump idle or at the limit of its capabilities

Criterion #1 - scope of equipment application

In most cases, experts advise installing heating pumps whose rotors are completely immersed in the coolant. Indeed, in addition to a low noise level, these types of units cope more successfully with high loads.

As a result, a system with “wet” equipment will last longer, be easier to repair, and will not require excessive attention.

Give preference to models that use durable steel and bearings, and the shaft is made of ceramic. Their advantage lies in their service life, which is at least two decades.

You should avoid purchasing a cast iron circulation pump. After all, such a device will quickly become unusable and require replacement.

If the choice fell on a “wet” type heating pump, then you need to take into account that it should not be installed in the heating system of an open-type cottage. Indeed, in this case, the heated water that lubricates the mechanism contains various impurities.

For example, microparticles of sand can clog the gap between the rotor and stator, which will lead to rapid pump failure.

As for open systems, this kind of equipment can function in them for years. Moreover, it will not require any specialized maintenance.

Criterion #2 - calculation of optimal power

The performance of a pump designed to operate in a heating system can be calculated independently. To do this, you will need the total length of the pipeline through which the equipment will pump the coolant.

For every 10 meters of length we take 0.6 meters of device pressure. So, for a small house with a heating circuit length of 70 meters, you will need a pump with a pressure of 4.2 meters.

You can go the other way and calculate this indicator using the formula:

Q = 0.86*R/TF-TR,

Where:

• R is the room’s heat requirement;
• TF and TR show the temperature of the coolant when supplied to the system and at its outlet, respectively. The values ​​used are degrees Celsius.

In European countries, two values ​​are predominantly used as the R parameter: 100 W/m2 for a house with one or two apartments, and 70 W/m2 for multi-apartment buildings.

The above method is just one of many ways to calculate the optimal power of a circulation pump. Only a qualified specialist can perform the most accurate calculations.

When you need to make calculations with minimal error, it is recommended to use special tables. They provide values ​​that are optimal for certain houses and apartments

Criterion #3 - number of speeds and pump noise

The main feature of modern pump models is the ability to customize them. You can regulate the power by switching the speed of the unit.

Today, the most common models are those with three speeds. This allows you to heat living quarters as quickly as possible during a sudden cold snap, and in case of warming, reduce the performance of the device, thereby saving energy.

If you need to buy equipment that produces the minimum possible noise, then the best choice would be a “wet” type pump.

If you install a unit with a “dry” rotor, during its operation you will hear an extraneous sound resulting from the rotation of the fan cooling the electric motor. Therefore, it is better to install such a device in a separate room, and for a living room choose something less loud.

The low noise level of “wet” pumps is the main reason for their popularity

Extraneous noise that appears during startup does not always indicate a malfunction. Quite often this happens due to air remaining in the heating system. To solve this problem, it is recommended to bleed air using special valves before starting.

Criterion #4 - manufacturer and price of equipment

After all the necessary calculations have been made, you can begin to view the catalog with circulation pumps. It is better to place an order on those web resources that have a well-thought-out product filtering system. This will allow you to quickly find models with optimal characteristics.

The current market offers a wide selection of pumps for heating systems. Hundreds of manufacturers say their products are reliable, quality and durable. But the stated characteristics do not always correspond to the real ones. Therefore, it is better to order equipment manufactured by manufacturers who have made themselves known throughout the world.

The following brands should be added to the list of well-known and reliable companies producing pumps for heating systems:

• Halm;
• Wilo;
• Ebara;
• DAB;
• AlfaStar;
• Pedrolo;
• Grundfos.

The cost of units for organizing forced pumping of coolant completely depends on the power, type of pump and brand. Typically, the price of equipment ranges from $60 to $220. We recommend that you familiarize yourself with the ten best heating pumps according to users.

As for domestic manufacturers, they do not produce household equipment, but offer only models intended for use for industrial purposes.

Most often, circulation pumps are mass-produced and have average parameters, which creates certain problems when choosing equipment. In this case, it is better to give preference to a device that operates in several modes

Video description

And some more thoughts about circulation pumps in the following video:

How to reduce the power of a gas boiler and will this help save money?

The most popular models of gas boilers are capable of solving not only heating problems, but also hot water supply problems. Moreover, the power of such equipment is represented by two main components: the power used to heat all premises (the sum of the power of the radiator batteries) and the power of the hot water supply, determined by the presence of large water consumers and the number of residents. In this material we will talk about how to reduce the power in a modern gas boiler and how advisable it is.

Do I need to reduce power?

In modern models of gas boilers equipped with highly sensitive automation, there is no need to independently reduce power indicators. In equipment of earlier production and the simplest units, similar measures are carried out:

• in case of alteration of the heating system with a significant decrease in the level of overall performance;
• in case of refusal of certain additional functionality, including dismantling the hot water supply system and “warm floors”.

If there are significant differences in the received and minimum power indicators, the equipment “clocks”, accompanied by constant turning on and off of the boiler. In this case, accelerated wear of working components such as the burner, three-way valve and pumping device is observed. In order to prevent boiler failure, it is necessary to reduce the power indicators in one of the available ways:

• replacement of the burner device with a modulating analogue;
• reducing fuel supply by changing valve settings;
• reducing power through service menu settings;
• regulating the functioning of the circulation pump.

In order to reduce fuel consumption, a thermostat is installed to ensure more accurate operation of the equipment, and weather-dependent automation devices are installed. A necessary condition for maintaining the high quality of operation of a gas boiler is proper maintenance of the unit, as well as increasing thermal efficiency by insulating the premises.

Reducing power through the menu

The task of adjusting the power of the equipment is to eliminate excessive cycling of the boiler operation in the absence of adapting the equipment settings to the heating system. It is possible to limit the maximum power indicators through the service menu if there is computer automation in the design.

In manual mode, you need to enter the service menu using a special code (not for all models), after which the required values ​​of the gas boiler power indicators are easily set. The transition to the service is performed through the control panel. A similar adjustment option is also suitable for effectively eliminating the pulsed operation of heating equipment (clocking).

All modern gas boilers with a modulating burner allow you to reduce power through the menu. To do this, just study the passport of your boiler and understand how to do it.

Gas valve adjustment

Net heat output can be reduced by reducing the fuel flow to the burner as a result of changing the valve setting. It is important to remember that the burner power is controlled by a complex electronics algorithm that takes into account several basic indicators, represented by the start time, temperature indicators, and the temperature difference in the direct pipe and the return pipe.

Adjusting the power indicators of the gas boiler burner is carried out by rotating special adjusting screws located on the valve body counterclockwise. More modern models are equipped with special automation that easily blocks clocking and changes power indicators. For this purpose, hold down the button with the wrench (5 seconds), and use special buttons to select the optimal duration of the intervals (0-15 minutes).

Other ways to optimize fuel consumption

Perhaps, if you are faced with high gas consumption, you do not need to reduce the boiler power. Measures should be taken to optimize the operation of the boiler.

The thermal energy created during the combustion of gas in a heating boiler is additionally consumed by the equipment in order to compensate for heat losses. Optimizing fuel costs will be especially relevant in winter, when the ambient temperature is sharply negative.

In order to reduce heating costs, it is necessary to provide an integrated approach to the issue of preparing premises, including insulation, replacement of windows and doors, and elimination of cold bridges. Among other things, it is mandatory to check the performance of all gas equipment in use and make adjustments to the mode of their normal operation.

Install Thermostat

Installing a thermostat for a heating boiler means increasing the efficiency of gas equipment by approximately 20-30%, maximizing operating accuracy and simplifying maintenance. Today, standard thermostats for a heating system are represented by a special temperature-sensitive sensor, a setting unit, a control module, a mechanical valve or an electromagnetic relay. The choice of model is determined by:

• typical characteristics of the boiler;
• wiring diagram of the heating system used;
• availability of free space and sufficient functionality.

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.

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.

How to increase and how to reduce the power of a gas boiler?

Each buyer, when choosing a gas boiler, must clearly know what power unit is suitable for his house or apartment. But it happens that the owner made a mistake in calculating the performance or the conditions changed during the operation of the unit: a boiler was connected, the heating area was increased due to an extension, the heating system was changed, etc.

• 1 How to increase the power of a gas boiler?
• 2 How to reduce power?

How to increase the power of a gas boiler?

It happens that the power of the existing gas boiler is not enough to meet all the needs placed on it. Often an increase in unit performance is required in the following cases:

• when re-equipping the heating system in order to increase its power, for example, adding the number of sections;
• when connecting an indirect heating boiler, heating of which will require about 20% of the unit’s performance;
• increasing the heated area due to extensions or adding previously unheated rooms.

There are different ways to increase the power of a gas boiler. The most reliable and optimal option is to call a service center specialist who can make settings and adjust the power of the unit so that it meets new needs.

It is worth noting that methods for increasing productivity may differ for different boiler models. If the unit has a modulating burner and the required indicator is within its power range, then you can simply adjust the burner device to the required performance.

Other pump calculation options

The above calculation method is one of the options for calculating the necessary parameters. A number of manufacturers use a different technique. You can also entrust the calculation of the circulation pump to a qualified specialist. Knowing the details of the design of a particular system and its operating conditions, he will professionally make all the calculations.

Usually the maximum load for the operation of the heating system is determined. In reality, it will be lower, so it would be wise to purchase a device whose parameters are slightly lower than the calculated data. Calculating the power of the heating circulation pump reflects the optimal result. Purchasing a more powerful device is not advisable and the system’s performance will not improve, and costs will increase.

After receiving the calculation results, it is necessary to pay attention to the pressure and flow data on pump models, taking into account its operating speeds. The characteristics can be reflected on a graph with two coordinates - pressure and productivity, and then the point of intersection of these values ​​can be determined

Based on the graphic image, the desired heating pump model is selected for a particular home. Point A in the figure corresponds to the required parameters based on the calculation results, and point B indicates the actual characteristics of a certain device model specified by the manufacturer. The circulation pump is more suitable for the operating conditions in a particular heating system, the smaller the distance between these two points.

Installation features

As a rule, circular electric pumps are installed in the main using a bypass - a parallel pipeline with a ball valve through which coolant is supplied when the pump branch is turned off. This design allows you to remove the circular valve for adjustment, repair or replacement without draining the coolant from the system.

Choosing the right circulation pump for heating is a responsible task, the solution of which is best left to specialists. The comfort and efficiency of the heating system (optimal efficiency of the device), as well as energy consumption, the savings of which, with the right solution, can reach 80%, depend on the selected unit.

If you wish, you can independently select a circulation pump for the heating system, make calculations using formulas; the highest accuracy of calculations is obtained when using computer programs. When working with programs, you need to understand how to enter data correctly - in many cases this requires special technical knowledge, which will take some time to obtain

Features of selecting a circulation pump

The pump is selected according to two criteria:

1. The amount of pumped liquid, expressed in cubic meters per hour (m³/h).
2. Pressure expressed in meters (m).

With pressure, everything is more or less clear - this is the height to which the liquid must be raised and is measured from the lowest to the highest point or to the next pump, if the project provides more than one.

Expansion tank volume

Everyone knows that liquid tends to increase in volume when heated. To prevent the heating system from looking like a bomb and leaking at all the seams, there is an expansion tank into which the displaced water from the system is collected.

What size tank should I purchase or make?

Everything is simple, knowing the physical characteristics of water.

We multiply the calculated volume of coolant in the system by 0.08. For example, for 100 liters of coolant, the expansion tank will have a volume of 8 liters.

Let's talk about the amount of pumped liquid in more detail.

Water consumption in the heating system is calculated using the formula:

G = Q / (c * (t2 - t1)), where:

• G – water consumption in the heating system, kg/sec;
• Q – amount of heat compensating for heat loss, W;
• c is the specific heat capacity of water, this value is known and equal to 4200 J/kg*ᵒC (note that any other coolants have worse performance compared to water);
• t2 – temperature of the coolant entering the system, ᵒС;
• t1 – coolant temperature at the outlet of the system, ᵒС;

Recommendation! For comfortable living, the temperature delta of the coolant at the inlet should be 7-15 degrees. The floor temperature in the “warm floor” system should not be more than 29 ᵒ
C. Therefore, you will have to figure out for yourself what type of heating will be installed in the house: will there be radiators, “warm floor” or a combination of several types.
The result of this formula will give the coolant consumption per second of time to replenish heat loss, then this indicator is converted into hours.

Advice! Most likely, the temperature during operation will vary depending on the circumstances and season, so it is better to immediately add 30% of the reserve to this indicator.

Let's consider the indicator the calculated amount of heat required to compensate for heat losses.

Perhaps this is the most complex and important criterion, requiring engineering knowledge, which must be approached responsibly.

If this is a private house, then the indicator can vary from 10-15 W/m² (such indicators are typical for “passive houses”) to 200 W/m² or more (if it is a thin wall with no or insufficient insulation).

In practice, construction and trade organizations take the heat loss indicator as a basis - 100 W/m².

Recommendation: calculate this indicator for a specific house in which a heating system will be installed or reconstructed. For this, heat loss calculators are used, with losses for walls, roofs, windows, and floors being calculated separately. These data will make it possible to find out how much heat a house physically releases into the environment in a specific region with its own climate regimes.

We multiply the calculated loss figure by the area of ​​the house and then substitute it into the water consumption formula.

Now you need to deal with the issue of water consumption in the heating system of an apartment building.

Technical specifications

When deciding how to choose a circulation pump for a heating system, consider its physical and technical characteristics, the main of which are:

• Bandwidth. Measured in cubic meters per hour or liters per minute, it shows the volume of liquid that the electric pump pumps per unit time; the higher the flow rate, the greater the flow rate. The indicator depends on the diameter of the pipeline used and can reach values ​​of up to 15 cubic meters per hour.
• Pressure The value is measured in meters of water column and indicates the height to which the electric pump can push liquid through a vertically installed pipeline. The maximum pressure of a circulating electric pump for varieties with a wet rotor is about 17 meters, although units with higher pressure characteristics may be found, but they are ineffective in operation (they have large overall dimensions and are too expensive).
• Temperature Range. It is clear that in a heating system, pumping equipment must withstand the maximum heating temperature of the coolant with a margin; commonly used modifications are designed for a maximum temperature of up to 110º C; some types can work with liquids with temperatures up to +130º C.
• Noise level. Basically, for use in individual homes, devices with a low noise level are chosen; such features have pumping equipment with a wet rotor, the noise characteristics of which do not exceed 35 - 40 dB.
• Compound. In residential individual houses, a heating main with a small cross-section of up to 1.5 inches is used - in this case, all pumping equipment is installed in the main using threaded connections (designed for pipelines with a diameter of up to 2 inches). The outlet fittings of most household electric pumps are equipped with external threads and are easily integrated into the line using American couplings.
• Dimensional parameters. The installation length is the main indicator of the device when built into a pipeline (for circular types, standard sizes are 130 and 180 mm), the diameter of the inlet and outlet pipes is also taken into account (standard 1 and 1.25 inches).
• Protection class. According to the international classification, the standard protection class for pumping equipment of heating systems is IP44 - this means that the unit is protected from the entry of solid mechanical particles with a diameter of more than 1 millimeter (the first digit in the marking) into the housing, and its electrical part is completely closed from drops and splashes, flying at any angle.

Common breakdowns

The most common problem that causes equipment that provides forced pumping of coolant to fail is its prolonged downtime.

Most often, the heating system is actively used in winter, and is turned off during the warm season. But since the water in it is not clean, sediment forms in the pipes over time. Due to the accumulation of hardness salts between the impeller and the pump, the unit stops working and may fail.

The above problem can be solved quite easily. To do this, you need to try to start the equipment yourself by unscrewing the nut and manually turning the pump shaft. Often this action is more than enough.

If the device still does not start, then the only solution is to dismantle the rotor and then thoroughly clean the pump of accumulated salt deposits.

Rules and nuances of equipment operation

A circulation pump is not bought for a year or even two. Therefore, every owner of a country house must ensure that the equipment is in good working order for many years. Reliability and correct operation of the device can only be achieved through correct and timely maintenance.

The list of basic rules for operating a heating pump must include the following aspects:

• it is prohibited to turn on the device with zero supply;
• make sure that the equipment is grounded;
• make sure that the electric motor does not heat up above the permissible norm;
• check the connection in the terminal box for the presence/absence of damage, and all cables must be completely dry;
• make sure that there is no extraneous noise or vibration when the device starts;
• the equipment must operate at the coolant flow level recommended by the manufacturer;
• It is forbidden to run the circulation pump without water.

If the equipment is idle for a long time, it is recommended to turn it on for 10-30 minutes every month. This simple rule will help avoid oxidation and, as a result, shaft blocking.

If any malfunctions or problems occur in the operation of the pump, you should call a specialist as soon as possible. This will help get rid of many problems and unplanned financial expenses.

Particular attention must be paid to the temperature of the coolant. It should not exceed 60-65 degrees Celsius. If you neglect this rule, sediment will appear in the pipes and inside the pump, which will negatively affect the operation of the entire heating system.

How to choose and buy a circulation pump

Circulation pumps face somewhat specific tasks, different from water pumps, well pumps, drainage pumps, etc. If the latter are designed to move liquid with a specific outlet point, then circulation and recirculation pumps simply “drive” the liquid in a circle.

I would like to approach the selection in a somewhat non-trivial way and offer several options. So to speak, from simple to complex - start with the manufacturers’ recommendations and lastly describe how to calculate a circulation pump for heating using formulas.

Select a circulation pump

This simple way to select a circulation pump for heating was recommended by one of the WILO pump sales managers.

It is assumed that the heat loss of the room per 1 sq. m. will be 100 W. Formula for calculating consumption:

Total heat loss of the house (kW) x 0.044 = circulation pump flow rate (m3/hour)

For example, if the area of ​​a private house is 800 sq. m. the required flow rate will be:

(800 x 100) / 1000 = 80 kW - heat loss at home

80 x 0.044 = 3.52 cubic meters per hour - the required flow rate of the circulation pump at a room temperature of 20 degrees. WITH.

From the WILO range, the TOP-RL 25/7.5, STAR-RS 25/7, STAR-RS 25/8 pumps are suitable for such requirements.

Regarding the pressure. If the system is designed in accordance with modern requirements (plastic pipes, closed heating system) and there are no non-standard solutions, such as high floors or long heating pipelines, then the pressure of the above pumps should be sufficient.

Again, this selection of a circulation pump is approximate, although in most cases it will satisfy the required parameters.

Select a circulation pump using the formulas.

If you want to understand the required parameters and select it using formulas before buying a circulation pump, then the following information will be useful.

determine the required pump pressure

H=(R x L xk) / 100, where

H—required pump head, m

L is the length of the pipeline between the most distant points “there” and “back”. In other words, this is the length of the largest “ring” from the circulation pump in the heating system. (m)

An example of calculating a circulation pump using formulas

There is a three-story house measuring 12m x 15m. Floor height is 3 m. The house is heated by radiators (∆ T=20°C) with thermostatic heads. Let's make the calculation:

required thermal power

N (from pl.) = 0.1 (kW/sq.m.) x 12 (m) x 15 (m) x 3 floors = 54 kW

calculate the flow rate of the circulation pump

Q = (0.86 x 54) / 20 = 2.33 m3/hour

calculate the pump pressure

The manufacturer of plastic pipes, TECE, recommends using pipes with a diameter at which the fluid flow speed will be 0.55-0.75 m/s, the resistivity of the pipe wall will be 100-250 Pa/m. In our case, a pipe with a diameter of 40mm (11/4″) can be used for the heating system. At a flow rate of 2.319 m3/hour, the coolant flow rate will be 0.75 m/s, the resistivity of one meter of pipe wall will be 181 Pa/m (0.02 mWG).

WILO YONOS PICO 25/1-8

GRUNDFOS UPS 25-70

Almost all manufacturers, including such “giants” as WILO and GRUNDFOS, post special programs for selecting a circulation pump on their websites. For the above-mentioned companies these are WILO SELECT and GRUNDFOS WebCam.

The programs are very convenient, they are quite easy to use

Particular attention should be paid to the correct entry of values, which often causes difficulties for untrained users

Buy a circulation pump

When purchasing a circulation pump, special attention should be paid to the selling company. There are currently a lot of counterfeit products on the Ukrainian market.

How can we explain that the retail price of a circulation pump on the market can be 3-4 times less than that of a representative of the manufacturer?

According to analysts, the circulation pump in the household sector is the leader in energy consumption. In recent years, companies have been offering very interesting new products - energy-saving circulation pumps with automatic power control. From the household series, WILO has YONOS PICO, GRUNDFOS has ALFA2. Such pumps consume several orders of magnitude less electricity and significantly save owners’ financial expenses.

A change in temperature outside is a reason to turn on a different speed

The presence of several modes in the heating pump will allow you to adjust the heating level in a particular room . This function is important when there is a sharp change in temperature outside. In this case, the device can be manually switched to the required power or the autopilot can be turned on, and the system itself will adjust to the desired temperature.

New pumps work differently...

To see the difference in the operation of modern pumps from non-modern ones, you need to understand how a conventional circulation pump with three speeds works.

Conventional circulation pump with three speeds:

We are already quite accustomed to this pump pressure-flow schedule

Pump characteristics

– this is the pressure-flow characteristic of the pump. Shows how the flow rate changes when exposed to a certain head loss resistance. The greater the flow rate in the pipe, the less pressure the pump creates (low hydraulic resistance of the system). The lower the flow rate, the higher the pump pressure (higher hydraulic resistance)

Intersection point

shows actual flow and head loss (in meters).

System characteristics

is the pressure-flow characteristic of the system as a whole. The system can be either a closed pipeline ring (heating) or an open ring (water supply).

You can find the operating point of the pump in this program:

There is another way to operate pumps. For example,

Consider GRUNDFOS ALPHA2 L

This pump is ideal for heating systems

This pump has 7 operating modes:

Pumping systems audit

Almost 20% of global electricity consumption comes from pumping systems. From 40% to 60% of the electricity consumed by pumping systems can be saved!

The three main cost items (acquisition, maintenance, electricity) over 10 years of operation are distributed as follows:

85% - energy costs

10% - technical and service maintenance

5% — purchase of equipment

It is the most expensive part of expenses (electricity) that can be significantly reduced! How? We suggest conducting an audit of the pump.

Performance Calculations

In order for the pump to work efficiently, you need to select its characteristics correctly. If you are unsure of the data, it is better to consult a specialist before purchasing. The easiest way to find out performance is using the following formula:

• G – volume of required coolant, l/h
• Q – total heating load, W. To make calculations easier, it is better to take a ratio of 1000 W per 10 m².
• Δt is the difference between the temperature of the water leaving the boiler and when returning to it. In calculations it is usually assumed to be 20° C.

For example, you need to choose a pump for a country house of 100 m². It will require 10,000 W to heat it. In this case, the calculation will look like this: G=0.86x10000/20=430 l/h =0.43 m³/h

In total, you will need a pump with a capacity of 430 liters or 0.43 m³/h.

Centrifugal pump malfunctions

Before starting the pump, it must be completely filled with water and the air must be released through the air bleeder. If air remains in the housing, there may be no pressure at all in the supply pipeline, or there will be weak pressure accompanied by noise during operation.

A decrease in the pump's rated head can be caused by a clogged suction line, strainer or impeller blades. To prevent clogging of the blades, coarse filters must be installed on the suction pipeline.

Pump head (m) is the energy received by a fluid weighing 1 Newton as it passes through the pump. Typically, pressure is considered from a geometric point of view, as the height to which liquid can be raised due to the energy generated by the pump.

A properly primed pump may not achieve rated flow if the total head does not match the pump parameters. To check the pressure, pressure gauges are installed on the suction and pressure pipelines. If the pressure is not enough to overcome the required height, you need to increase either the shaft speed or install a larger impeller. If, on the contrary, the supply is greater than the pressure height, then the power on the pump shaft increases, which leads to overload of the engine. To avoid this, it is necessary to adjust the operating mode of the valve on the pressure pipeline.

Flow (m 3 /s) is the performance of the pump, i.e. volume of liquid pumped per unit time

The direction of movement of the pump shaft must correspond to the specified one. Otherwise, the pump may fail due to jamming of the impeller shaft, which in turn will damage the housing. To prevent the shaft from spinning in the opposite direction, a check valve is installed on the pressure pipeline.

Increasing the maximum permissible suction lift is a common cause of pump failure. This leads to the possibility of flow rupture, causes the phenomenon of cavitation, and also significantly reduces power. The maximum suction lift depends on the temperature of the liquid, its speed in the suction pipeline, as well as on the resistance at the outlets and friction losses. As the temperature of the pumped liquid increases, the maximum suction lift decreases as the vaporization pressure increases. Friction losses can be reduced by making the suction pipeline as large in diameter and short in length as possible with the minimum required number of shut-off valves. It is also necessary to regularly clean the filter mesh, since dirt accumulated in it significantly increases power loss.

The permissible suction height (m) is the maximum vertical distance from the liquid level in the supply tank to the suction pipe of the pump, at which cavitation does not occur.

Installing a pump with too high a pressure leads to its unreliable operation, since the permissible suction height will be greatly exceeded due to the high flow.

If high pressure of vaporization occurs in the suction pipeline, back-up should be provided, which will also cover friction losses. The minimum head height is usually determined by the manufacturer and is indicated in the pump specifications. To ensure uninterrupted operation of the pump, it is necessary to maintain the required head pressure, which depends on the temperature of the pumped liquid and the pump flow. If liquid is pumped from a closed reservoir, then the head height can be ensured by increasing the pressure in it.

If the suction pipeline is long, it must be laid with a slope towards the pump to prevent air from entering it. When drawing liquid from the tank, the suction pipe must be immersed in it by at least 0.8 m.

After the pump, a shut-off valve must be installed on the pressure pipeline, since the circulation pump is turned on and off with the pressure pipeline closed. If the pressure exceeds 10 - 15 m, then a check valve is installed between the valve and the pump. It prevents fluid from flowing back through the pump during an emergency stop (eg power outage). Also, the absence of a check valve can lead to reverse rotation of the pump shaft during a short-term power outage.

Failure to timely service the seals can cause damage to the centrifugal pump. The causes of damage to the stuffing box are uneven rotation and runout of the working shaft. The oil seal box is tightened with such force that a little water drips out from under it. This creates dry friction for the stuffing box and ensures its cooling. Strong tightening of the oil seal leads to dry friction, as a result of which the durability of the bushing decreases, and if strong local heating occurs, it can be destroyed.