It was believed by many that for domestic performance it is necessary to take circulation pumps with a wet rotor. Dry rotary circulation pumps were used for industrial use.

There was an opinion that pumps with a dry rotor were too large and very noisy. However, large manufacturers began to produce more and more household models circulation pumps with a dry rotor.

Dry rotor circulation pumps are used in industry.

In the domestic version, circulation pumps with a wet and dry rotor are used. For production needs, pumps with a wet rotor are not used, since they can be produced with a power of up to 3 kW and they are not widely used.

Advantages of circulation pumps with a dry rotor of industrial design: the quality of the coolant is not important for them, they have good maintainability. The disadvantage of these pumps is that they are large, very noisy, so they are installed in separate rooms, consume a lot of electricity.

As for the household version of the pump with a dry rotor, its advantages:

has a higher efficiency;

for him, the purity of the coolant is not important;

has good maintainability, and spare parts are cheaper than pumps, having a wet rotor;

almost does not differ in size from the wet rotor counterpart.

The downside is a lot of noise during operation and the need for regular replacement of the mechanical seal.

The disadvantages of circulation pumps with a dry rotor are pluses for a pump with a wet rotor: noiselessness, does not have a mechanical seal. The disadvantage is that the quality of the coolant has great importance during operation. The worse the quality of the pumped liquid, the faster the pump can fail.

Considering all the minuses and pluses of the considered pumps, we can draw the appropriate conclusions. If the quality of the coolant is not important to you, then it is better to choose a pump with a wet rotor, but it is not known what will happen to the rest of the heating system.

If you want everything to work smoothly, it is better to use a dry rotor motor, but you also need to take care of the quality of the coolant.

As for the noise, everyone decides for himself, because the pump does not often come into view. The efficiency is not so important, since the percentage difference is small, but the absence of the need to replace the mechanical seal is a big plus.

But maintenance should be carried out regularly, together with an inspection of the entire heating system by a specialist.

With the development of technology, improved and developed newest species heating systems. Now in many markets circulating dry and wet rotors are widely used, due to their qualities such as efficiency, convenience and reliability of operation.

You can see a circulation pump for heating systems in almost all stores where it is sold Appliances, in the markets or get acquainted with the characteristics on our resource.

Advantages

• Unlike heating systems that do not include this mechanism, the device is able to turn on in a matter of minutes and begin to perform its functions. Rapid overclocking of the system allows for a short time heat up the room.
• The presence of this equipment in the system increases the efficiency of the heating circuit in general, and ensures high efficiency.
• The use of a circulation pump in the distribution of the system guarantees the reliability and trouble-free operation of heating rooms as a whole. These models are also easy to use.
• The pump is very handy. It can be placed anywhere in the room and from the right place it will provide high-quality air circulation.

Forced circulation scheme

Types of circulation pumps

Types and types of heating circulation pumps are in large numbers. The article will consider the most common types of pumps.

Glandless circulation pump - the impeller and rotor are located so that they immediately begin to process the liquid. Working wheel a glass made of stainless steel separates from the stator. The working shaft can be made of both metal and ceramics. The liquid processed by the rotor simultaneously maintains the temperature of the engine, cooling it, and performs the functions of lubricating the rubbing parts.

wet rotor

The assembly of pumps with a wet rotor is carried out according to a special principle, called modular. Depending on the performance and pressure, the selection of the appropriate modules is carried out. This design simplifies repairs when only the module is replaced in the event of a breakdown. It is very important to keep in mind that it is not necessary to remove air from the volute of a wet rotor. The air is removed automatically by the rotor itself.

And the second type of equipment is a circulation pump with a dry rotor. The dry rotor takes its name from the design and principle of operation of the device. Structurally, the impeller and the rotor do not come into contact with the treated water. This type circulation pumps are used to work with a large volume of water in heating.

Dry Rotor

Unlike the above type of pump, the dry rotor mechanism incorporates special seals. They are located in the middle between the drive and the pump housing. The formed film of water between the surfaces during operation seals the pump. Depending on the operational use, the rings can be made of ceramic, stainless steel, agglomerated carbon. Pumps for heating with a dry rotor are available with flanged motors and motors connected by a coupling.

Choice

Which is better to choose a circulation pump for a heating system? When heating, the main attention is paid to such a parameter as the heat generated, with which the device will provide the room. In organizations that evaluate instrument parameters, the data is evaluated using special programs, then after the calculation, real calculations are issued.

Product design

One of the popular methods for choosing a pump is to estimate the area of ​​​​the room that the pump is able to heat. According to European standards, houses with two or less apartments require 100 watts per square meter for heating. And for houses with many apartments, 70 watts per meter. And depending on the quality of thermal insulation, power parameters depend. If the thermal insulation is good, then 30 - 50 watts per square meter is needed.

For poor quality thermal insulation, high power indicators are taken.

For our harsh climate, the following data correspond:

• for two-story house at an air temperature of minus 25 degrees - 173 watts per square meter, if minus 30, then 177 watts per square meter;
• for a building of more than two floors, 97 and 101 watts per square meter are suitable, respectively.

If you have some knowledge of calculating the power of pumps, then you can correctly calculate and calculate which circulation pump is needed for your home.

Installation

Installing a circulation pump in a heating system will not take much time if you have the necessary tools and skills for this:

1. keys in a set with sizes from 17 to 36;
2. bypass, filter, check valve;
3. "American" carvings.

To connect the pump to the heating system, you should be guided by:

Installation options

• The technical parameters of the pump, which are calculated as shown above;
• Attaching the mechanism to the return pipelines will ensure the operation of devices with chilled water. This will extend the life of the products. also connect to the return pipeline;
• With the heating boiler turned off, the inlet and outlet valves on the pump pipe are closed. Then the product should be installed in a horizontal position, tightening with the help of "American" nuts. Vertical equipment will create extra noise during operation.

An important tip: when installing a gasket, it is better to choose one made of paranite, because the rubber ones will become unusable when the temperature rises.

• The installation of a circulation pump will be an addition if the circulation is natural. Here it is worth at the same time to purchase a filter and "American" nuts, suitable for the device in diameter. For closed wiring, a check valve will be needed, but for open wiring it is not needed at all;
• When installing, do not forget to install taps that will be useful when repairing the system. The bypass line, when installed, will allow circulation to continue when the device is removed and even in the event of a power outage.

Conclusion

Here it is worth noting that it is best to choose equipment from well-known manufacturers. Circulation pumps, powered by 12 volts, will ensure reliable operation. As well as additional emergency batteries or diesel generators, useful for emergency shutdown electricity. For large houses, products with lower performance are suitable.

Your contacts in this article from 500 rubles per month. Other mutually beneficial cooperation options are possible. Write to us at [email protected]

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

In working condition, a pump with any type of rotor pumps a volume of liquid through the pipes, forcing it to move constantly forward. As a result of such an impact on the coolant, we have the following advantages:

• Constant temperature indicator of radiators in all parts of the heat supply system;
• The absence of air locks in the system, which means the elimination of the possibility of water hammer in it;
• Saving family money on fuel or electricity consumption for heating the coolant (now you do not need to intensively fire the boiler so that the desired water temperature reaches the radiators in the back room of the house and warms it up). Glanded 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 performs its work, moving it along a closed circuit.

Circulation pumps are similar to drainage pumps device. The pump housing with a dry or wet rotor is most often made of durable alloys such as brass, cast iron, stainless steel or bronze. Such metals perfectly interact with water at high temperatures or with aggressive media (in the case of a drainage rotor).

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

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

When turned on, the rotor drives the impeller wheel, which rotates fast enough to create a pressure drop in the pump chamber. This encourages the flow of water into the tank. Further, the water that has entered 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 repeats over and over until the unit is turned 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 the nodes 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 water layer. It helps to maintain the pressure difference in the heating system and in the working chamber, which means that it ensures the tightness of the rotor compartment. At the same time, at the moments of operation of the ring, the seals 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 principles of operation, the 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 stops;
• Economical power consumption;
• Ease of installation, configuration, maintenance and repair.

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

Important: but along with all listed benefits The efficiency of a pump with a "wet" type rotor is significantly lower and is about 55%. Thus, it is best to use a similar mechanism in homes. small area, where closed loop the heating system is short.

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

Important: required condition quality work pumps with a "wet" rotor and compliance with the principles of pumping water is correct installation unit per circuit. Here, the equipment shaft must be located strictly horizontally relative to the closed circuit of the heating system. Only in this case, a high-quality flow of fluid to the bearings for lubricating the working units will be ensured through the sleeve.

Dry Rotor Pumps

Here the principle of operation of the mechanism is that the rotor works without contact with water. At the same time, it differs high level The efficiency of such a device, which reaches as much as 80%.

For all their productive capacity, units of this type have a number of disadvantages:

• High noise level in 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 impurities in the water or air molecules. Such "neighbors" are able to 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 aggregates, in which the engine is in a vertical position, and both nozzles are located on the same axis;
• Console (horizontal), in which the engine is mounted horizontally, and the nozzles are perpendicular to each other.

Pump selection rules: dry or wet rotor

In order for the heating system to work as efficiently as possible, it is necessary to choose the right pump in accordance with the parameters of the house and the characteristics of the heating system. Only in this case and under the condition correct installation mechanism 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 ​​\u200b\u200bthe house and the length of the closed circuit of the heating system;
• The number of radiators for the entire length of the heating system;
• The presence of "warm floor" systems, etc.;
• Quality and density of window metal-plastic packages;
• Insulation of walls, ceiling or roof in the house.

Important: calculations required amount heat should be carried out only by competent heat engineers who will take into account all important nuances and recommend a pump with nominal pressure characteristics for your premises.

It is important to consider that if you choose a pump for a heating system that already exists, but needs to be improved, then it is better to buy an adjustable unit. This device perfectly adapts to the operating parameters of a given circuit.

Mounting principles for units with any rotor

In order for the operation of the circulation equipment to be of high quality, it is better to invite specialists to install it. But if you want to install the pump yourself, then follow these rules:

• The installation of the unit is carried out at the boiler from the reverse type. That is, where the water passed the whole closed loop system, again comes back. 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 housing when installing it. The arrow should look in the direction of the movement of warm water through the system.
• All flanged 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, which, in case of repair of the unit, will be able to close the heating circuit after removing the pump.

Popular Wet Rotor Pump Models

The most popular units for transporting water with wet rotors are products manufactured by German, Danish and Canadian companies. A special place among the product range is occupied by the Wilo pump.

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 circulation systems cold water at enterprises.

Grundfos pumps

Another leader in the modern Russian and world markets of pumping equipment. These pumps are highly efficient and reliable. Thanks to careful assembly from scrupulous Danes, the units work without failures and breakdowns for a long time.

The salient features of these mechanisms are:

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

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

Glandless circulation pumps

In the section "Pumps" we will talk about pumps for heating with a "wet" rotor. The circulation pump is very important element in heating, air conditioning, hot water, and floor heating systems. Thanks to the pump, the coolant circulates in the “closed” heating system, the “warm floor” system, which increases heat transfer. When using a pump, smaller diameter pipelines can be installed, hence reducing the amount of coolant in the system, reducing the consumption of energy carriers and reducing the cost of the costs of the materials used, although it is necessary to additionally install. Such heating systems react faster to temperature fluctuations and are easier to adjust. The use of circulation pumps in heating systems allows saving up to 30% of energy carriers used to heat the coolant. Pumps for hot water supply (DHW) allow you to maintain a constant temperature of water in hot water systems (recirculation hot water). 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 hot water. Pump housings for heating systems are made of cast iron, while hot water pump housings are made of bronze or brass. Circulating pumps for heating systems with wet rotor work constantly throughout heating season, therefore, high requirements are imposed 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 wet rotor pumps.

Device and design

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

The design of pumps with a "wet" rotor

Mounting methods

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

or as the Americans also call them, a threaded connection with a conditional passage of 1 ″ and 1 1/4 ″. Pumps bigger size have flange 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 carry out installation on the return pipeline. The arrow on the pump housing 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 gate valves of the same diameter as the nominal diameter of the pump. Valves or gate valves are used for the convenience 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 mount a coarse filter of the same diameter as the nominal diameter of the pump. If several circulation pumps are used in the heating system, then on each of them it is necessary to install check valves. The valve is installed with the same diameter as the nominal diameter of the pump and is mounted after the pump on the discharge pipe up to the shut-off valve. In case the axis of the motor shaft is mounted vertically (fig.)

in relation to the horizon, during operation, an air lock may form in the upper part of the separation sleeve. A ceramic or graphite bearing will not be lubricated by the pumped liquid, which can lead to its 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, the cooling of the stator will deteriorate due to insufficient fluid circulation. To do this, the liquid must constantly circulate through the separating cup. More information about installation methods can be found in the installation and operation 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. Pump head always equal to the resistance systems. The flow that the pump can provide also depends on the pressure. It must be remembered that the feed should not fall below a certain minimum. Otherwise, poor performance may cause strong rise temperature in the pump chamber, which can damage the pump. To avoid this, the pump manufacturer's instructions must be followed. Working point outside operating characteristic pump may cause overheating and failure of the pump. When the flow changes during pump operation, the pressure also changes, and, consequently, the operating point is constantly shifting. It is up to the designer to find the calculated operating point in accordance with the requirements when operating the system in maximum mode. All other operating points are to the left of the calculated operating point. The figure shows the effect of changing the hydraulic resistance on the displacement of the operating point.

Moving 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 \u003d Q N / 1.163 * Δυ (m 3 / hour)

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

QN – thermal power boiler in [kW]

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

Δυ - the calculated temperature difference in the direct 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 the conditional passage of pipelines, the following formula can be used to approximate the pressure of the heating system:

H=R *L*ZF/10,000 (m)

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

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

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

In the presence of shut-off valves and thermostatic valves, you need to use the coefficient ZF=2.2.

In the presence of shut-off valves, thermostatic valves and a mixer, you need to use the coefficient ZF=2.6.

10000 – conversion factor (m) and (Pa)

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

For a temperature difference Δυ=20 K (supply temperature=90 °C, return temperature=70 °C), the head is: Q=QN /1.163*Δυ (m 3 /h)=50/1.163*20=2.15 m 3 / hour

When heating a similar building with a lower temperature difference (e.g. 10 K), the circulation pump must provide a double flow rate, i.e. 4.3 m 3 /h, provided that the heat produced by the heat generator can reach the consumers in the required amount.

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

the total length of the direct and return pipelines is 150 m, the coefficient is 2.2, since there is no mixer and thermostatic valves. As a result, we get the head (H): H \u003d R * L * ZF / 10000 (m) \u003d 50-150-2.2 / 10000 \u003d 1.65 m.

Operation maintenance and repair

Circulation pumps for heating systems are reliable and efficient equipment that works for a long time under the right operating conditions. But pumps with a "wet" rotor have one serious shortcoming. of these pumps does not exceed 50%, while for dry rotor pumps this figure can reach 80-90%. Therefore, such pumps are most in demand in individual heating and hot water systems.

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

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

In practice, it often happens that the coolant contains fine suspension and scale. When the pump is running, the scale gradually settles and builds up on the working surfaces of the rotor and the glass. The distance between the rotor and the glass is 0.1-0.2 mm, due to the build-up of scale, the rotor "jams" in the glass. If a pump with a “jammed” rotor is energized for a long time, then this defect can lead to more serious damage: overheating and short circuit windings. The stator fails, as the coolant flow decreases or completely stops, and the engine is not cooled enough. Unfortunately, motor rewinding workshops do not take into operation the stators of domestic circulation pumps, because of their high labor intensity and difficulty in rewinding, as a result, the purchase of a new pump. If the pump stator has not failed, then it takes quite a lot of time to wedging 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 careless movement. 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 is formed in heating systems operating on the "natural" circulation of the coolant, since it was necessary to add water 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 over the 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 they do not encounter the problem of rotor jamming.
• Install in heating system

The second reason for the failure of pumps is the presence of suspension in the heating system. Suspension enters the ceramic bearings, and wear is formed on the bearings and the shaft (this happens especially quickly on bearings made of graphite). Due to development, play appears and extra noise, and at one fine moment the rotor “sticks” to the glass. Simply put, the rotor stops spinning. 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.

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

Thank you for your attention.

pump rotor

pump rotor this is a separate assembly unit, which largely determines the efficiency, reliability and durability of the pump.

The basic part of the circulation pump rotor is the shaft on which the impeller, protective bushings, seals, parts of the hydraulic unloader, half-coupling and others are installed. small parts attached to the shaft.

At the end of the rotor, an impeller is fixed, which is fixed from displacement in the axial direction by a nut or fairing (depending on the type and design of the pump).

Glandless pump

Structurally, in a pump with a “wet” rotor, the working medium moves in the cavity between the rotor and the stator. In this case, in order to avoid a short circuit, the rotor and stator are protected by special cylinders (jackets) made of stainless steel. The working medium in this case lubricates the surfaces of the rubbing parts of the pump, such as bearings, and at the same time cools them.

The advantages of a wet rotor pump include high reliability, such pumps are almost silent and have a long service life.

The disadvantages of such pumps with a wet rotor include low efficiency, on average up to 50%, which decreases as a result a large number barriers between rotor and stator. Low efficiency leads to increased power consumption.

Dry rotor pump

In pumps with a dry rotor, there is no contact between the rotor and the working medium. Between the engine and the working medium, movable hermetic - mechanical seals or non-hermetic - stuffing box seals are installed.

The advantages of a dry rotor pump include high efficiency, up to 80%, and therefore relatively low energy costs.

The disadvantages of a pump with a dry rotor include a high level of noise, so these pumps are installed in separate soundproof rooms.

Modern wet and dry rotor pumps.

Currently, many manufacturers, both foreign and "domestic", provide circulation pumps with a wet and dry type of rotor. Such pumps are used in most cases for installation in heating and air conditioning systems.

The pumps are capable of pumping medium with temperatures up to 110 degrees Celsius, at pressures up to 10 atm.

The material of the pump body is cast iron. The pumps are available in both single-speed and multi-speed versions and have a low noise level.

Wet rotor circulation pumps are used to provide home heating.

Wet pumps are especially popular. wilo rotor Star-RS, TOP-RL series, etc.

And Grundfos wet rotor pumps of the ALPHA2, ALPHA3 series, etc.

But such pumps, in addition to their compact size and low power, are still not able to heat truly large rooms.

This requires, for example, wilo dry rotor pumps of the BL series. Or dry rotor pumps grundfos series TP.

Should these pumps be installed?

Should I buy a wet rotor pump or a dry rotor pump? Such a question may arise for any person who thinks about creating an uninterrupted circulation of the coolant in the heating system of a cottage or a private house.

During operation, each of the pumps with any type of rotor causes the liquid to move through the pipes. As a result of such an impact, you get:
constant temperature of heating radiators in any point of your house;
removal of air pockets from the pipeline system, and as a result, the elimination of hydraulic shocks;
saving the budget and electricity for heating the coolant.

Pump rotor design

In a wide variety of pumping equipment, one or more impellers can be installed on the rotors of pumps of different types and purposes. The pump device with one impeller is called single-stage, if there are several wheels, then the pump is multi-stage.

If the impeller and the motor drive are mounted on the same (common) shaft, then this type of pump is called cantilever.

V industrial design the most common options are when the pump shaft and the motor shaft are connected by coupling halves, which are fastened together with steel rubberized cylinders / screws - “fingers”.

Most of the rotor parts are mounted on the shaft with keys. Parts installed without a keyed connection must be securely fastened against rotation.

The absence of noise and vibration during operation of the pump is due to the balancing of the rotor assembly. This requirement is met by careful static balancing of individual parts of the rotor and subsequent dynamic (during rotation) balancing of the assembled rotor.

The most suitable design of the pump rotor to ensure balance is a non-separable one. A non-separable design is a design in which the impeller is seated on the shaft with an interference fit.

Wheel tension on circulation pump rotor provide heating of the impeller or cooling of the rotor.

In the vast majority of pumps at a speed of up to 3000 rpm, a collapsible rotor design is used, in which the wheel is seated on the shaft along a movable fit on the keys. The impeller in this case is installed in a sliding or tight fit, which ensures the smallest possible gaps.

Pump rotor material

The most common material for the pump rotor shaft is carbon steel grades 35 and 45, as well as structural alloy steel 40X or 40XH. For corrosive liquids, 3X13 stainless steel shafts are used.

If the pump design requires the use of bobbit-filled plain bearings, carbon steel protective sleeves should be mounted on the shaft journals, since stainless steel can form scuffs.

Protective sleeves are either screwed onto the shaft or pressed in axial direction with round nuts. The direction of the thread must be chosen taking into account the direction of rotation of the shaft to prevent self-unscrewing during operation.

All variants of heating pumps from the most popular manufacturers with the possibility of selection for specific parameters