Differences between pumps with a “wet” and “dry” rotor. Heating pumps with a wet rotor Pumps with a wet rotor

The uninterrupted and safe operation of the heating system of a country cottage is one of the first and most important issues that must be resolved when designing engineering systems. Therefore, it is very important to know how to choose a circulation pump for heating a private house, what parameters need to be taken into account, and how to avoid pitfalls during operation.

When is a circulation pump needed?

The circulation pump provides a given rate of energy flow in an autonomous heating system (in a central system, this role is played by industrial units). The need for it arises already in the presence of one of the following factors:

wiring of 2 or more circuits;

route duration is more than 50 m;

at least with 1 level difference;

the presence of a complex circuit (warm floor system);

heating 2 or more floors;

installing a boiler in the basement;

in a heating system with free movement of energy when the temperature difference between the incoming flow and the return flow is more than 15-20 ºС;

when the temperature difference is more than 1-2 ºС in the radiators of one system.

The circulation pump in a short time creates the required speed of coolant movement in all circuits, ensuring uniform temperature distribution. The difference between the outlet and inlet temperatures, when installed correctly, should be about 10 ºС, which saves fuel and ensures careful operation of the boiler. The efficiency of the system increases by an average of 20-50%, which becomes noticeable both in stable room temperature and in saving money.

Principle of operation

Circulation pumps for heating private houses are a closed structure consisting of an electric motor and a working element - a flywheel or rotor.

Water enters the cavity (recess) of the pump, where it is given centrifugal motion by moving blades. Next, the water enters the spiral channel and, by inertia, with the already acquired speed, a spiral flow that reduces hydraulic resistance, flows further. At this point, a vacuum is created, into which a new portion of water is sucked in.

Pump modifications and technical parameters

Based on the design features, the pumps are characterized by the productive power of the engine, the type of rotor and control.

Engine

An accurate calculation of engine parameters is performed for a specific heating system, but the general selection rule is simple - power is proportional to the performance (size) of the working part.

Rotor or flywheel

There are 2 principles of rotor operation:

Dry. The rubbing parts and the rotor itself are located in a hermetically sealed housing - only the blades that create the flow come into contact with water. Such models are characterized by high power and efficiency, but are more sensitive to mechanical contamination of the energy carrier. It is required to undergo annual technical maintenance of the electric motor. In addition, their installation should be carried out away from living rooms due to the increased noise level.

Dry rotor circulation pump – motor and blower are located in separate housings

Wet. The most common type due to its ease of maintenance, cost and variety of models. In an open design, moving parts (bearings, shafts, rotor, etc.) are in water, which is both a lubricant for them and a coolant for the engine. Appropriate stainless alloys and gaskets made of waterproof materials are used. The system is less demanding of mechanical impurities in the energy carrier, and the service life of the household appliance is designed for 7 years.

In a glandless pump, the motor and blower are located in the same housing

Work management

Pump control is the choice of speed modes, on which the efficiency of the entire system depends. For heating, the minimum mode is used, while at low temperatures, rapid heat removal requires an increase in speed. To regulate this process, 2 types of control are used:

Mechanical. The speed selection is made independently, and switching is done manually. This control is effective for small circuits where the response to speed changes occurs quickly. Heating pump in a private house, most often, is purchased with such control due to its low cost and higher maintainability.

Smart upgraded models controlled by an automation system, which, depending on the temperature of the coolant, regulates the flow rate. They cost more, but when installing multi-component systems with collectors, they are indispensable. In addition, they increase energy efficiency by 25-35%.

Each manufacturer uses its own developments that promote trouble-free operation during the shelf life, so prices for models with the same characteristics differ, as well as the quality of the equipment.

The cost reduction in cheaper companies occurs due to the minimum safety margin. Most often, this means reducing the thickness of non-critical elements of parts, using less durable and cheaper materials, which are only sufficient for the specified service life. The choice of manufacturer largely determines the quality characteristics of the product. You can navigate them by reading reviews or delving into the study of the materials used for parts.

On our website you can find contacts of construction companies that offer house insulation services. You can communicate directly with representatives by visiting the “Low-Rise Country” exhibition of houses.

What to consider when choosing

How to choose a circulation pump for the heating system of a private house, and what parameters you need to know for this. Since the pump is a power unit, the first selection criterion will be its power. Next, we determine the type of rotor, and lastly, the type of control.

To determine the power, you need to know the parameters of the heating system. For large objects: industrial, multi-story, measurements are taken. In private homes such accuracy is not needed, so it is enough to know:

Boiler performance. The calculation is made theoretically using the formula: W thermal boiler * K throughput (1l/min=60l/hour). For 25 kW 25*60= 1500 l/hour; for 40 kW 40*60= 2400 l/hour.

Pressure. Indicated in meters of water column. For this calculation, you need to measure the total length of the contour and multiply by a factor of 0.6 (10 linear meters correspond to 0.6 m w.s.). For the circuits of a one-story house, standard equipment of 6 m w.c. is sufficient, while 2 or more floors require the installation of a station or several pumps.

Rotor type. Affects cost and subsequent maintenance. Increased efficiency allows its use in complex systems. But taking into account the possibility of remote installation and regular maintenance.

Control. It also affects the cost of the unit itself, but convenience and efficiency more than make up for this drawback. In complex systems it is recommended to use only this type of control.

Pressure and air relief valve. It is not installed in all models, but you can overpay for this function, since it prevents the pump from turning on “dry” and ensures trouble-free shutdown during a power outage (the water heats up to a critical temperature, the pressure increases and the outlet valve opens).

Manufacturers

Pumps in this category, regardless of the company, must be replaced after the end of their service life, since there is a high probability of stopping due to sudden breakdowns. The units are divided by manufacturer, since each of them focuses on performance, cost and reliability, and the final characteristics of the pump differ.

European - as a rule, all work in the middle or high price segment and offer high quality. The price reduction is due to optimal design solutions and marketing policies, including the transfer of production to China.

The German manufacturer stands out for its high quality and efficiency Grundfos– these models are equipped with energy-saving technologies. The declared service life is at least 10 years.

Company Wilo also produces high-quality industrial and household models, mainly with electronic control.

DAB- Italy. With regular maintenance, the pumps work flawlessly. The company spends a lot of money to eliminate noise in dry-type pumps.

Chinese - in addition to the price, you should pay attention to the company.

The company's models have proven themselves well Oasis. First of all, this is the cost, which is 30% less than Russian and European analogues. At the same time, operation is guaranteed throughout the declared service life.

Russian ones, like other participants, work in accordance with European GOSTs and comply with all safety requirements.

Among Russian manufacturers, the most famous company is the Subline Service brand. UniPump. Manufactures pumps of various types. The models are characterized by their low cost and the use of the most efficient technologies.

Wester belongs to the company "Impulse". Produces products in a limited range. The pumps are distinguished by good assembly and the use of parts with a high margin of safety.

Company Gilex models " Master" And " Compass" The line includes pumps for small circuits and 2-3 storey systems.

Where to install the pump correctly

When installing pump for heating private houses, how to choose The location of installation is no less important an issue than the characteristics of the equipment itself. Here you need to take into account the operating principle of the unit, the type of system and the number of its circuits.

One of the options for connecting a circulation pump to the heating system

The pump can be installed both at the inlet and outlet, providing convenient access to it for technical inspections and maintenance. In most cases, they prefer to install pumps at the inlet so that the pump pumps water at a lower temperature, but the main criterion is still ease of maintenance.

Video description

You can see the installation of supply or return pumps in the video:

Important! Installing a pump between radiators or in front of the expansion tank creates vortex flows that disrupt the direction of movement, creating temperature differences in different parts of the system. It is therefore very important that the pump is located between the boiler and:

radiator system;

collector;

expansion tank.

In a double-circuit system, with the connection of “warm floors”, a separate pump is installed for each circuit.

Installation of the system, which includes a circulation pump, is carried out with the connection of a backup power supply with a operating reserve of 4-6 hours.

For 1;-2-circuit systems, the installation of a bypass is mandatory, since in the event of a power outage it will ensure the natural movement of energy flow in the system.

For reference! A bypass is a bypass, a small section of pipe with shut-off or adjustable valves, sometimes with a check valve. It is built to bypass the circulation pump and when it stops it ensures free flow movement.

The operation of the pump can only be checked when the system is full. The main indicator of correct installation is the uniform distribution of heat between all radiators.

Pumps with a wet rotor type are installed in a vertical position.

Installation of a coarse filter is required, and installation of a fine filter is desirable.

The pump must be located in a place accessible for maintenance.

After all the calculations, add 20% of the rated power, so you will ensure gentle operation of the equipment in the optimal mode of 85-90%, excluding operation at the limit of possibility.

Solid fuel boilers

This type requires separate consideration. When the electricity is turned off, the pump stops, but heating of the energy carrier in the boiler continues: it is impossible to quickly extinguish burning wood or coal, after 3-5 minutes the temperature will reach critical levels and the pressure relief valve will operate. If the pump is installed on the outlet pipe, the reset occurs after 4-6 minutes, while its installation on the return pipe increases this time to half an hour.

Video description

You can see the installation of a pump in a system with a solid fuel boiler in the following video:

Price factor

When choosing a circulation pump, the cost of the device itself and its efficiency in operation are important. As a rule, the operation of the pump is justified by savings on fuel consumption, and the cost of the model itself is determined by its performance. In Moscow, the price range for pumps is very large. Conventionally, they can be divided into 3 categories:

For 3.5-7 thousand rubles you can buy basic functions, with a minimum operating life and most often one-time use;

Devices costing 7.5-20 thousand are “workhorses” that accurately provide the stated characteristics, with a service life no less than that specified by the manufacturer and with several degrees of protection and an optimal safety margin;

VIP systems with full automation, a set of additional functions, a high safety margin and the ability to provide a large volume of heat will cost from 20 to 45 thousand rubles.

Video description

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

Advantages of a separate pumping unit

The use of pressure equipment is justified from the point of view of saving fuel and increasing boiler efficiency, which is why many companies integrate pumping units into boilers. But installing the unit separately has its advantages: quick replacement without removing the boiler, the ability to control the process in case of emergency situations (for example, using a bypass). In addition, the pump can be installed in a system not provided for by the project at the initial stage.

Conclusion

Despite the apparent simplicity of the choice, the parameters of the pump must be technically justified, for which mathematical calculations are carried out taking into account the laws of heat engineering, the individual characteristics of the system, therefore the exact choice must be made by a specialist who takes into account all factors based not only on theoretical knowledge, but also on practical experience.

If, in the case of choosing a pump, the question arose, which is better - a pump with a wet rotor or a dry one, then we will try to understand such units using the example of circulation pumps. It is known that such equipment is successfully used to create excellent and uninterrupted coolant circulation in the heating system of a private home.

In operating condition, a pump with any type of rotor forces a volume of liquid through the pipes, forcing it to constantly move forward. As a result of this effect on the coolant, we have the following advantages:

• Constant temperature indicator of radiators in all areas of the heating system;
• The absence of air locks in the system, which means eliminating the possibility of water hammer in it;
• Saving family money on fuel or electricity consumption for heating the coolant (now there is no need to fire the boiler intensively so that the desired water temperature quickly reaches the radiators in the back room of the house and warms it up). Wet or dry rotor pumps will make everything faster and more productive.

Important: pumps with rotors of all types have two openings in their design: suction and discharge. Thus, the unit does its job, moving it along a closed circuit.

Circulation pumps have a structure similar to drainage pumps. The pump body with a dry or wet rotor is most often made of durable alloys such as brass, cast iron, stainless steel or bronze. Such metals interact well with high-temperature water or aggressive media (in the case of a drainage rotor).

The rotor itself is made of either durable stainless steel or ceramic. And the working unit (wheel with blades) is placed on the rotor shaft.

The operating principle of such a device is to create centrifugal force inside the pump and looks like this:

When turned on, the rotor drives a wheel with an impeller, which rotates quite quickly, creating a decrease in pressure in the pump chamber. This promotes the flow of water into the tank. Next, the water that gets into the chamber increases the pressure and at the same time is pressed against the walls of the internal reservoir of the pump. As a result of this difference, water is pushed out into the outlet. The cycle is repeated again and again until the unit turns off.

Division of pumps with a rotor into types

All pumping equipment with a rotor can be divided into two types:

• Units with a “wet” rotor;
• Pumps with a “dry” rotor.

In the first case, we are talking about a mechanism whose rotor does not have direct contact with the pumped water. The isolation of the rotor in the pump mechanism is supported by special ceramic or metal seals in the form of rings. They protect the rotor from direct contact of components with the pumped medium. But here the principle of operation of a device with a wet rotor is that between the protective rings rubbing against each other there is a thin, barely noticeable layer of water. It helps maintain the pressure difference in the heating system and in the working chamber, and therefore ensures the tightness of the rotor compartment. At the same time, during operation, the sealing rings rub against each other more strongly, which ensures even greater tightness of the device.

Important: circulation units for heating or air conditioning systems with a “wet” rotor can be either single-phase or three-phase. That is, such pumps can be used both at home and in a large production or industrial enterprise.

Thanks to precisely these operating principles, a unit with a “wet” rotor has a number of advantages:

• Low noise level when pumping water through the system;
• Modest weight and small dimensions;
• Possibility of long-term operation without stopping;
• Economical energy consumption;
• Easy to install, configure, maintain and repair.

At the same time, monoblock devices with a “wet” rotor are more popular among modern consumers.

Important: but along with all the listed advantages, the efficiency of a pump with a “wet” type rotor is significantly lower and is about 55%. Thus, it is best to use such a mechanism in houses with a small area, where the closed circuit of the heating system is of short length.

If we talk about water supply pumps with a “wet” type rotor, then here too the devices will be slightly inferior to their counterparts with a “dry” rotor. But this applies only to surface aggregates.

Important: a prerequisite for high-quality operation of a pump with a “wet” rotor and compliance with the principles of pumping water is the correct installation of the unit on the circuit. Here the equipment shaft must be positioned strictly horizontally relative to the closed circuit of the heating system. Only in this case will a high-quality supply of fluid to the bearings for lubrication of working units be ensured through the sleeve.

Pumps with a dry rotor

Despite all their productive power, units of this type have a number of disadvantages:

• High noise level during operation.
• The need for constant monitoring of the quality of the processed medium, since pumps with a “dry” rotor do not tolerate the presence of foreign debris in the water or air molecules. Such “neighbors” can break the tightness of the sealing rings in the mechanism.

At the same time, the entire range of pumps with a “dry” rotor is divided into three types:

• Block devices;
• Vertical units, in which the engine is in a vertical position and both pipes are located on the same axis;
• Console (horizontal), in which the engine is mounted horizontally and the pipes are located perpendicular to each other.

Rules for choosing a pump: “dry” or “wet” rotor

In order for the heating system to work as efficiently as possible, it is necessary to select the right pump in accordance with the parameters of the house and the characteristics of the heating system. Only in this case and provided that the mechanism is correctly installed in compliance with the principles of its operation, the heat in the house will be of high quality and long lasting.

So, when choosing a pump, consider the following points:

• The total area of ​​the house and the length of the closed circuit of the heating system;
• Number of radiators for the entire length of the heating system;
• Availability of “warm floor” systems, etc.;
• Quality and density of window metal-plastic bags;
• Insulation of walls, ceilings or roofs in a house.

Important: calculations of the required amount of heat should be carried out only by competent heating engineers, who will take into account all the important nuances and recommend a pump with pressure characteristics rated specifically for your room.

It is important to take into account that if you choose a pump for a heating system that already exists but requires modification, then it is better to buy an adjustable unit. This device perfectly adapts to the operating parameters of a given circuit.

Principles for installing units with any rotor

In order for the circulation equipment to work efficiently, it is better to invite specialists to install it. But if you want to install the pump yourself, then follow these rules:

• The unit is installed on the return side of the boiler. That is, where the water, having passed through the entire closed loop of the system, returns back again. But this rule applies to premises whose area does not exceed 150-200 m2.
• It is important to follow the location of the arrow on the pump body when installing it. The arrow should point in the direction of the movement of warm water through the system.
• All flange and threaded joints must be treated with sealant to avoid possible leaks.
• If you are dealing with a reverse circulation heating system, then it would be useful to install a bypass - a piece of pipe that, in the event of repairs to the unit, can close the heating circuit after removing the pump.

Popular models of pumps with a wet rotor

The most popular units for transporting water with “wet” type rotors are products manufactured by German, Danish and Canadian companies. The Wilo pump occupies a special place among the range of products.

The devices have a threaded connection and are equipped with a speed control system to control the performance and power of the pump. Wilo units are used in heating and air conditioning systems, as well as in cold water circulation systems in enterprises.

Grundfos pumps

Another leader in the modern Russian and global pumping equipment markets. Such pumps are characterized by high performance and reliability. Thanks to careful assembly by meticulous Danes, the units operate without failures or breakdowns for a long time.

Distinctive features of such mechanisms are:

• Absolute inertness to water and anti-corrosion properties of the metal;
• No need for frequent preventive maintenance and repairs (the wet rotor does its job);
• Reliable sealing of the housing.

Important: Grundfos pump casings are equipped with a special heat-protective casing, which prevents the risk of possible burns to the user.

Glandless rotor pumps, which can be purchased in Moscow at a budget price in the EGM-SHOP.ru online store, are designed to complete autonomous heating, hot water supply and air conditioning systems low-rise residential buildings and cottages.

Their main purpose is to maintain uninterrupted coolant circulation for the most efficient distribution of thermal energy and timely supply of hot water to water consumption points.

Design of DAB glandless pumps

The name of circulation pumps with a wet rotor reflects their key design feature - rotation rotor in the pumped coolant, thereby ensuring cooling electric drive and lubricants bearings.

For guard stator a special system is provided to prevent coolant from entering separating glass carbon fiber or stainless steel.

Advantages of DAB circulation pumps with a wet rotor

• A wide range of models and designs, from simple inexpensive to energy-efficient frequency-controlled;
• Three speed modes allowing you to adjust the heating speed of any room;
• Low noise level during operation;
• Light weight and compact dimensions;
• Long period of non-stop work;
• Quick and easy installation and configuration;
• Minimal maintenance;
• High maintainability.

In addition, pumps for circulating water and increasing pressure in the heating system, equipped with a wet rotor, reduce costs for space heating and hot water supply. They consume less energy and are designed to complete pipelines with a smaller cross-section, which allows rational consumption of heat due to the rapid and intensive movement of the coolant.

Wet rotor circulation pumps

In the “Pumps” section we will talk about heating pumps with a “wet” rotor. The circulation pump is a very important element in heating, air conditioning, hot water supply systems, as well as in floor heating systems. Thanks to the pump, the coolant circulates in a “closed” heating system, a “warm floor” system, which increases heat transfer. When using a pump, it is possible to install pipelines of a smaller diameter, hence reducing the amount of coolant in the system, reducing energy consumption and reducing the cost of materials used, although additional installation is required. Such heating systems respond faster to temperature fluctuations and are easier to adjust. The use of circulation pumps in heating systems allows saving up to 30% of the energy used to heat the coolant. Hot water supply (DHW) pumps allow you to maintain a constant water temperature in hot water supply systems (hot water recirculation). When choosing a circulation pump, it is necessary to consider where the pump will be used in the heating or hot water supply system. Structurally, the pumps have a clear division into pumps for heating and domestic hot water. Pump casings for heating systems are made of cast iron, while for hot water supply casings made of bronze or brass are used. Circulating pumps for heating systems with wet rotor operate continuously throughout the heating season, so high demands are placed on them: silent operation, low power consumption, simplicity and reliability. There are two most common types of circulation pumps - pumps with a “wet” and “dry” rotor. In this article we will talk about pumps with a “wet rotor”.

Device and design

Structurally heating pumps with wet rotor consist of four main elements: stator, rotor, separating glass and housing (photo).

Design of wet rotor pumps

Installation methods

Union nuts are manufactured and supplied for pumps with a “wet” rotor (photo)

or as they are also called by American women, a threaded connection with a nominal bore of 1″ and 1 1/4″. Larger pumps have flanged connections. Circulation pumps for heating systems can be mounted directly on the pipeline in a horizontal or vertical position, provided that the axis of the pump shaft must always be horizontal. They can be mounted on both supply and return pipelines. It is preferable to install on the return line. The arrow on the pump body for heating systems indicates the direction of movement of the coolant. Before and after the circulation pump, it is necessary to install shut-off valves or valves of the same diameter as the nominal bore of the pump. Taps or valves are used for ease of pump maintenance during maintenance or repair. In this case, the coolant does not need to be drained from the heating or hot water supply system. Between the shut-off valve and the suction pipe of the pump, it is imperative to install a coarse filter of the same diameter as the nominal bore of the pump. If the heating system uses several circulation pumps, then check valves must be installed on each of them. The valve is installed with the same diameter as the nominal bore of the pump and is mounted after the pump on the pressure pipe up to the shut-off valve. If the motor shaft axis is mounted vertically (Fig.)

in relation to the horizon, during operation an air plug may form in the upper part of the separation glass. A ceramic or graphite bearing will not be lubricated by the pumped liquid, which can lead to overheating and, as a result, jamming of the rotor shaft. As we have already said, the bearings of wet rotor pumps are lubricated by the pumped liquid. In addition, stator cooling will deteriorate due to insufficient fluid circulation. To do this, the liquid must circulate constantly through the separating glass. More information about installation methods can be found in the installation and operating instructions for circulation pumps for heating systems.

The point at which the characteristics of the circulation pump and the system intersect is called the operating point of the system and the pump. This means that at this point there is a balance between the useful power of the pump and the power required to overcome the resistance of the heating system. The pump pressure is always equal to the system resistance. The flow that the pump can provide also depends on the pressure. It must be remembered that the feed should not be below a certain minimum. Otherwise, low performance may cause a strong increase in temperature in the pump chamber, which can lead to damage to the pump. To avoid this, follow the pump manufacturer's instructions. An operating point outside of the pump's operating curve may result in overheating and failure of the pump. When the flow changes while the pump is operating, the pressure also changes, and, consequently, the operating point constantly shifts. Finding the design operating point in accordance with the requirements when operating the system at maximum speed is the task of the designer. All other operating points are to the left of the calculated operating point. The figure shows the effect of changing hydraulic resistance on the displacement of the operating point.

Shifting the system operating point to the left of the calculated operating point increases the pump head. This will lead to increased noise in the heating system in the presence of control fittings and valves.

Pump delivery

To determine the flow in the heating system, the following formula is used: Q=Q N /1.163*Δυ (m 3 /hour)

Q– pump flow at the design point in [m 3 /h]

Q N– boiler thermal power in [kW]

1,163 – specific thermal capacity of water [Wh/kg*K]

Δυ – the calculated temperature difference in the forward and return pipelines of the heating system, in kelvins [K], while 10–20 K can be taken as a basis for standard systems.

Pump head

To deliver the pumped coolant to any point in the heating system, the pump must overcome the sum of all hydraulic resistances. Since it is usually quite difficult to determine the laying pattern and conditional passage of pipelines, the following formula can be used to approximately calculate the pressure of the heating system:

Н=R *L*ZF/10 000 (m)

R– friction losses in pipes [Pa/m]. In this case, we can take as a basis the value of 50 Pa/m - 150 Pa/m for standard systems (depending on the year the house was built; in older houses, due to the use of larger diameter pipes, the pressure loss is less (50 Pa/m)).

L– length [m] of forward and return pipelines or: (length of the house + width of the house + height of the house) x 2

ZF- coefficient. for shut-off valves ≈1.3, thermostatic valve ≈1.7, mixer ≈1.2

If there are shut-off valves and thermostatic valves, you need to use the coefficient ZF=2.2.

If you have shut-off valves, thermostatic valves and a mixer, you need to use the coefficient ZF=2.6.

10000 – conversion factor (m) and (Pa)

Example: a boiler installed in an old apartment building has a power of 50 kW.

For a temperature difference Δυ=20 K (supply temperature=90 °C, return temperature=70 °C) it turns out that the pressure is equal to: Q=Q N /1.163*Δυ (m 3 /hour)=50/1.163*20=2.15 m 3 /hour

When heating a similar building with a smaller temperature difference (for example, 10 K), the circulation pump must provide double flow, that is, 4.3 m 3 /hour, with the condition that the heat produced by the heat generator can reach consumers in the required quantity.

Pressure loss due to friction in the pipeline is 50 Pa/m in our example,

the total length of the forward and return pipelines is 150 m, the coefficient is 2.2, since there is no mixer and thermostatic valves. As a result, we obtain the head (H): Н=R*L* ZF/10000(m)=50-150-2.2/10000=1.65 m.

Operation, maintenance and repair

Circulation pumps for heating systems are reliable and efficient equipment that operates for a long time, subject to operating conditions. But pumps with a “wet” rotor also have one serious drawback. of these pumps does not exceed 50%, while for pumps with a dry rotor this figure can reach 80-90%. Therefore, such pumps are most in demand in individual heating and hot water supply systems.

Circulation pumps for heating systems with a “wet” rotor cannot be operated without coolant flow - overheating of ceramic or graphite bearings may occur and, as a result, jamming of the rotor.

To reduce noise in closed heating/cooling systems with circulation pumps, it is necessary that there is no air in the system. Automatic air valves or are used to remove air.

In practice, it often happens that the coolant contains fine suspension and scale. When the pump operates, scale gradually settles and layers on the working surfaces of the rotor and bowl. The distance between the rotor and the glass is 0.1-0.2 mm; due to scale deposits, the rotor “jams” in the glass. If a pump with a “jammed” rotor is under voltage for a long time, then this defect can lead to more serious damage: overheating and short circuit of the windings. The stator fails because the coolant flow decreases or completely stops, and the engine is not cooled sufficiently. Unfortunately, motor rewinding workshops do not use stators of household circulation pumps because of their high labor intensity and difficulty in rewinding, which results in the purchase of a new pump. If the pump stator has not failed, then it takes quite a lot of time to wedge the rotor: from several hours to several days. This procedure is especially difficult with pumps that have a ceramic shaft. The shaft of such pumps is very fragile and can break if moved carelessly. As a rule, it was possible to wedge all the rotors that were repaired with such a defect.

To reduce scale in the heating system, you must:

• Flush the heating system before commissioning. Especially a lot of scale forms in heating systems that operate on “natural” coolant circulation, since it was necessary to add water very often to the expansion tanks, and this water is not prepared. After installing a circulation pump in such a system and poor flushing of the heating system, all the scale that has accumulated for years in pipes and radiators with slow natural circulation very quickly ends up in the pump due to the fact that the coolant speed has increased several times.
• Fill the heating system with special softened water.
• Do not drain the coolant from the system after the end of the heating season.
• After the end of the heating season, it is necessary to turn on the pump for 1-2 minutes at least once a month, so that at the beginning of the heating season you do not encounter the problem of rotor jamming.
• Install in heating system

The second reason for pump failure is the presence of suspended matter in the heating system. The suspension gets into the ceramic bearings, and wear forms on the bearings and shaft (this happens especially quickly on graphite bearings). Due to exhaustion, backlash and additional noise appear, and at one point the rotor “sticks” to the glass. Simply put, the rotor stops rotating. There are practically no spare parts for circulation pumps, and you have to buy a new pump. To prevent such defects, it is necessary to follow the same procedures as when the rotor is jammed.

To summarize, we can say that modern heating systems, both in individual and urban buildings, require high-quality pumping equipment that can ensure efficient circulation of the coolant. For long and reliable operation, it is necessary to comply with the installation conditions and operating rules. The pumps used must meet very stringent requirements: to be economical, reliable and ensure continuous operation during the heating season for many years.

Thank you for your attention.

Such products are widely used both on an industrial scale and in everyday life. They are compact devices that perform the function of pumping liquids through pipelines. Mainly installed in hot water supply, heating and cold water supply systems.

Due to the design and application features, even with a long route, to ensure reliable operation of the circuit, it is enough to install a circulation pump of relatively low power.

They are used not only to ensure the movement of water. They are capable of pumping liquid media whose temperature ranges from -40 to +130 0C. Asynchronous motors are used as the power element. Circulation pumps are classified in different ways. Depending on the design, they are divided into 2 types: models with a “dry” and “wet” rotor. This difference in engineering solution largely determines their functional purpose.

What are circulation pumps with a dry rotor made of and what are they?

The design of the circulation pump with a “dry” rotor provides increased power, which significantly increases its productivity. Such models are capable of creating high pressure in systems and are used for long-distance pipelines, or if it is necessary to supply fluid to a great height. That is why they found their main use for industrial purposes.

They consist of two main parts - an electric motor and the pump itself - which have a coupling connection. They got their name because the rotor does not have direct contact with the liquid. In turn, they are all divided into subspecies.

• KM (console K) are an assembly mounted on a common platform. The axes of the pump and motor are located strictly on the same line. They are most widely used in urban water supply systems and in enterprises to meet production needs. Can work with both clean and contaminated liquids.

• Cantilever-monoblock KMLs are considered low-pressure. The pump and motor are mounted in a common housing. They are easier to operate and maintain, therefore they are more widely used in public utilities and are installed in general building utilities. The design of a circulation pump for heating is simple and is no different from the design of models used in other systems.

What these subspecies have in common is that the inlet and outlet pipes are located at an angle.

• “In-line” pumps are distinguished by the fact that they can be installed directly on the pipe line. Their pipes are located on the same axis. By design they are more reliable. The natural wear and tear of the connecting rings (between the pump and the motor) during operation is automatically compensated by a pressure spring. “Self-fitting” of parts occurs.

Design features of pumps with a “wet” rotor

Models with a “wet” rotor are characterized by a low level of noise generated. They are of interest from the point of view of domestic use. They are widely used in the installation of autonomous heating systems in private buildings or in small administrative and industrial premises. The pump rotor is located directly in the liquid.

They are attractive because they are easy to repair at home. But in order to eliminate the malfunction, you need to know the design features. Therefore, let’s take a closer look at how a circulation pump with a “wet” rotor works.

As a rule, cast iron is used to make the body of models for heating, although products are produced in which the body is made of stainless steel (non-ferrous metals, aluminum, bronze, brass). They are used for hot water supply and cold water supply systems. The rotor is placed in a special glass and is rigidly connected to the impeller (impeller).

This achieves its isolation from the stator. The peculiarity of the technology is that the shaft can be either metal or ceramic. It is secured in plain bearings (graphite or ceramic). The volute, on which the inlet and outlet pipes are located, is attached to the body using bolts, which are unscrewed with a special key (hexagon) supplied with the product.

There is a plug on the front (end) part of the pump; by unscrewing it, excess air can be released. Although it is also possible to automatically remove it during operation. For this purpose, an air vent is located in the upper part. There is a box for electrical connection with an operating mode regulator.

When the plug is completely unscrewed, access to the shaft opens, on the end of which there is a slot for a screwdriver. Thus, you can manually scroll if the pump does not start after a long “idle period” (for example, due to salt deposits). Perhaps the only drawback of such pumps is their low efficiency. If for “dry” models it is within 70–80%, then for “wet” models it does not exceed 55%.

But at the same time, such a circulation pump design has a number of undeniable advantages:

• the liquid it pumps simultaneously cools and lubricates the parts;
• upon startup, the products automatically remove trapped air;
• The pumps are assembled according to a modular principle. Therefore, when repairing, it is enough to replace the faulty part;
• due to low power, they consume little electricity;
• switching of operating modes is provided, which allows you to choose the most optimal one;
• the ability to automatically regulate the start and stop process when using a temperature sensor, which also reduces energy consumption;
• absolute silence in operation;
• does not require maintenance.

The latest models of “wet” pumps are produced shaftless. The impeller (also known as the rotor) rotates on ceramic bearings under the influence of the electromagnetic field created by the stator winding. This significantly simplified the design (no shaft and oil seals) and increased reliability and durability. Even if small fractions get inside along with the liquid, it will not affect the operation of the pump.