Gravity heat supply systems fully function only in single-storey private houses with an area of up to 100 square meters. m. If it is necessary to heat an apartment building or a spacious mansion, then you can not do without a forced circulation system. The best solution is to select a circulation pump and install the unit in the heating circuit.
We offer you to understand what tasks the pump performs in the heating system, how the device is arranged and works. We described the features of operation of different types of pumps and identified the main criteria for a competent choice. The information provided will help you choose the right circulation pump model and not be disappointed in your purchase.
Why does a heating system need a pump?
Circulation pumps - hydraulic equipment that provides forced movement of a heated coolant in a closed circuit. Such devices contribute to a uniform and quick heating of the entire system.
Circulation pumps set:
- in order to increase the energy efficiency of boiler equipment;
- in cases where it is not possible to ensure the natural circulation of a liquid substance;
- in the absence of a mounted pump unit in the heat generator;
- for heating systems with a two-pipe scheme, allowing you to adjust the parameters of each individual radiator;
- to overcome the inertia of autonomous systems with natural circulation of fluid used to transfer thermal energy.
The coolant must move along the closed circuit of the heating system pipe at a certain speed to ensure heat transfer to the radiators.
With natural circulation, this condition is not always feasible - as a result, the heating equipment does not heat up or heats unevenly.
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Circulation pump in the heating system
Use in narrow pipe construction
Collector circulation pumps
Installing the appliance in a heating pipe
Application of a backup pump
Connection of a volatile device
Low power equipment
Multi-ring heating system
Therefore, circulation pumps are installed in the heat supply systems. Such devices provide transportation of the coolant over the network at high speed, minimizing the load on the boiler. When you return to the heating element, the water remains warm, which means that less energy is required for heating.
Design and principle of operation of the pump
By design, the circulation pump resembles a drainage installation. The pump consists of a robust housing made of stainless steel / cast iron / aluminum and an electrical part that includes a stator winding with an integrated ceramic / steel rotor.
Installation of a pumping device for forced circulation significantly increases the efficiency of hot water supply systems and autonomous heating
The impeller is fixedly fixed on the shaft of the rotating part of the electric motor.
The impeller is two parallel discs connected by radially curved blades. On one of them is a hole for the flow of coolant, on the other a small hole for fixing the impeller on the shaft of an electric motor.
The body parts of the circulation pumps are made of steel and durable alloys. Under the walls of the housing is a hidden rotor with a fixed impeller
The electric motor itself is equipped with a special control board and terminals for connecting wires. For circulation pumps without electronics, a capacitor is installed instead of the board, and a speed switch is located on the terminal box.
When power is supplied, the wheel with the blades rotates, creating a vacuum in the nozzle and pumping the coolant. The rotor creates a movement of the working fluid in the direction from the inlet to the outlet valve.
The pump constantly draws water on one side and pushes it into the heating system on the other. Centrifugal force facilitates fluid transportation throughout the line.
The created pressure overcomes the resistance in different parts of the circuit and ensures the circulation of the coolant.
Judging by the intensity of sales, the most popular in the domestic market are devices from the following manufacturers:
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Grundfos brand circulation device
Wilo logo product line
Devices for heating systems from DAB
Gileks circulation pump
Types and advantages of circulation pumps
According to the design features, pumps for forced circulation are divided into pumping units with a wet rotor and high-performance devices with a dry rotor.
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Assembly option for a closed heating system
Vacuum expansion tank - expansomat
Air vents
Pressure relief valve
Wet type pumps. The rotor and impeller of such pumps are in direct contact with the working fluid, which simultaneously performs two important functions: the role of lubrication and cooling of the device. The rotor and stator in such pumps are separated by a special vessel responsible for the tightness of the elements of the electric motor under voltage.
Wet-type circulation pumps are equipped with a step speed controller. This allows you to choose the optimal mode of operation, and therefore control energy consumption.
The rotor of the electric motor and the impeller in the pumps are in the pumped water, which moistens the supporting elements and constantly cools the motor (+)
Wet rotor units have a modular design. Separate modules are selected depending on the required pressure and performance. The prefabricated design greatly simplifies the repair of the pump, since a failed module can be easily and quickly replaced with a new one.
This type of circulation pump is used in small heating systems. They operate almost silently, and therefore are excellent for installation in residential premises.
The electric motor of the pumps with a wet rotor does not need additional cooling, since it is constantly in contact with water. There is a small number of working parts inside the pump, which minimizes the need for frequent maintenance.
The main advantages of using "wet" type pumps:
- low noise level;
- small overall dimensions and small weight;
- minimum electricity consumption;
- easy parameterization, maintenance and repair;
- long term of operation.
Wet rotor units also have disadvantages. They are very sensitive to the quality of the working fluid. The presence of fine abrasive particles in water leads to accelerated wear of the hydraulic part of the pump.
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The location of the circulation pumps in the heating circuit
Installation of the device in the supply pipe
Placement relative to a broad tank
Mandatory use of a security group
In addition, the efficiency of such circulation pumps does not exceed 55%. However, this indicator is quite sufficient for pipelines of small length, and therefore pumps that directly contact with water are often used in individual heating systems.
For trouble-free operation of wet-type units, the pump must be installed correctly. The main requirement is a strictly horizontal spatial orientation of the shaft. Only with this configuration is a complete lubrication of the bearings with fluid provided.
Proper installation of the circulation pump is the key to stable operation of the heating system throughout the entire period of operation
Dry rotor pumps successfully used for pumping large volumes of coolant in large installations. The rotor assembly of such devices does not come into contact with water.
The body part of the circulation pumps of the "dry" type is made of durable cast iron or galvanized steel. The surface is coated with special protective compounds to prevent corrosion phenomena.
Dry rotor units are suitable for collective use in residential high-rise buildings, entertainment centers and offices, and industrial facilities.
The design of the pumps of the "dry" type provides increased power. Such pump models are able to create a lot of pressure in heating circuits (+)
There is a special sliding seal between the electric motor and the pumping part of the pump (2 protective rings), which isolates the basic functional elements from liquid ingress.
These rings are well polished and are in close contact with each other. One of them (dynamic) is mounted on a rotating shaft. The static wheel is firmly fixed in the pump casing.
A thin water film reliably seals the connection of the protective rings due to differences in pressure indicators in the circuit and the environment.
For the manufacture of o-rings, coal obtained by the method of oil sintering is used. Some modifications of pumps designed for use in extreme conditions have metal / ceramic protection rings.
The efficiency of dry rotor devices reaches 85%. This is an excellent indicator compared to wet pumps. However, “dry” units make a lot of noise due to the cooling fan, and therefore they are mounted in separate rooms with good sound insulation.
Dry type circulation pulsers come in 3 types:
- monoblock;
- cantilever;
- "In-line".
One-piece pumps belong to the category of low pressure units. The electric motor and pump in such devices are mounted in one unit. They are easy to operate and maintain. Suitable for use in public utilities and apartment buildings.
Cantilever Pumping Devices collected on a single basis, while the axes of the pump and motor are on the same line. The suction pipe is located on the outer part of the cochlea, and the discharge pipe is on the opposite side of the housing.
If cantilever units are installed at production facilities, as well as in urban water supply systems, then In-line pumps are installed directly on the pipeline
In-line pumps mounted directly on the pipeline. The suction inlet and discharge outlet pipes are located on the same line, an automatic compensation mechanism for the production of o-rings is provided.
Benefits of using dry rotor circulation pumps:
- high performance;
- energy efficiency;
- low requirements to the quality of the energy carrier - the pumped liquid may contain neutral impurities;
- simple repair and replacement of spare parts.
In addition, today manufacturers of heating equipment offer potential customers dual models of pumps. Such devices are used to reserve power and additional safety in emergency situations.
Twin pump motors can function together or separately. If one pump breaks down, the second device continues to operate normally, ensuring uninterrupted operation of the boiler.
Reliable and trouble-free operation of the heat supply system will be ensured by dual circulation pumps, in which two impellers are connected in parallel
With proper operation, the life of the circulation pump is at least 10 years.
How to choose the right pumping equipment?
The efficiency of the pump depends on the basic parameters - productivity and pressure. Productivity shows the amount of heat transfer fluid that the unit must pump per unit of time. This parameter is determined from the conditions of maximum load.
Head - a value that expresses the energy of the fluid flow used as a heat carrier. It takes into account the hydraulic resistance of the entire system.
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The choice of the circulation pump for the heating system is based on regulatory requirements. For normal heating and silent movement of water along the circuit, the coolant must move at a speed of no more than 1.5 m / s
Technical data obtained experimentally confirm that for 10 m of pipe length there should be 0.6 m of pump head. Those. for a pipeline with a length of 50 m you need a device that creates a pressure of at least 3.0 m
Since the circulation pump must provide unimpeded flow of coolant to the heating devices, that is, the relationship between radiators and the flow that the pump develops. If the total battery power is 7 kW, then the pump should pump 7 l / min
When choosing a circulation pump, it is very important to take into account the power of the boiler, with which it will work in the system. For each kW of the unit, 1 l / min of flowing coolant must be distributed. for heating equipment with a power of 25 kW you need to buy a pump that provides a flow rate of at least 2.5 l / min
Heating with five circulation pumps
Selection of equipment along the length of the pipeline
Interrelation of power of radiators and pump
Selection of the pump according to the boiler power
You should also pay attention to the maximum temperature. Since the pump will pump hot water, it must withstand temperatures up to 110 ° C.
It is very important to choose the right capacity of the circulation pump. A low-power device will not cope with pumping the coolant fluid in the required volume. Pump parameters are selected based on the calculations.
If you install a more powerful unit, an unpleasant noise will appear in the pipeline. Also in this case, the functional elements of the boiler equipment will wear out much faster than stated by the manufacturer.
The power of the circulation pump must be sufficient to cope with the hydraulic resistance in a closed circuit
Experts recommend choosing a circulation pump at the design stage of the heat supply system. If the length of the pipeline does not exceed 80 m, just install one pump. With a greater length, it is advisable to mount several pumping devices at once.
When buying, you should pay attention to the materials from which the functional elements of the pump are made. Most parts are directly / indirectly in contact with heated working fluid, and therefore subject to rapid wear.
Therefore, it is advisable to give preference to circulation pumps with ceramic bearings and a rotor assembly.
An important role is played by electronics. To regulate the temperature indicators inside the premises, thermostatic valves are installed in the heating circuits. When the temperature rises, they overlap, the pressure in the pipes increases.
As a result of these processes, an unpleasant noise appears. In order to get rid of it, it is necessary to transfer the circulation pump to lower speeds, and doing it manually is inconvenient.
Pumps with integrated electronics will help you quickly and efficiently cope with this task.Such units smoothly regulate pressure drops in the pipeline depending on changes in the amount of liquid.
The main advantages of modern pumps are efficiency and durability, compact overall dimensions, low noise level, automatic operation mode, convenient control panel
It is worth noting the additional functionality of the pumps, namely:
- smooth adjustment;
- speed control;
- automatic operation mode;
- built-in informative display.
The simplest models of circulation pumps are without the ability to control the rate of fluid transport. Modern multifunctional pumps are two / three-speed units with infinitely adjustable. They are highly accurate settings.
Equipment operating in automatic mode is equipped with a control panel. The settings of such devices are extensive and depend only on the modification of devices.
This can be automatic speed control depending on changes in temperature indicators of indoor air, an electronic timer for turning off / on, automatic pump startup at a minimum flow rate.
The presence of a digital display makes it possible to obtain all the necessary information about the operation of the pumping device: temperature of the heat-transfer fluid, resistance in a closed loop, performance, errors, etc.
The subtleties of calculating the pressure and performance in the video clip:
Video about the device, the principle of operation and installation of the circulation pump:
A modern heat supply system with a built-in pump for forced circulation allows you to heat residential premises in a matter of minutes after starting the heat generator.
Rational selection of the circulation pump and high-quality installation significantly increase the efficiency of the use of boiler equipment due to the saving of energy resources by about 30-35%.
Looking for a circulation pump for a heating system? Or have experience operating such installations? Please share your experience with readers, ask questions and participate in discussions. The comment form is located below.