Natural pressure drops do not always provide the required coolant head in heating systems with one or more circuits. A water pump for heating, built directly into the boiler equipment, will help to get it. Before using it, it is important to understand the device and the technical characteristics of the units, as well as understand the main criteria for choosing the right sample.
Purpose and device
Water pumps for heating a private house are built into the circuits in order to create a pressure sufficient for the circulation of the coolant. They contain the following elements:
- a housing with a working chamber located in it;
- impeller electric motor;
- air bleeding mechanism;
- junction (terminal) box with wiring diagram.
The last of these elements includes additional electromechanical equipment designed to control the operating mode of the electric motor.
The simplicity of the design of the pumping units guarantees their reliable operation during the entire service life declared by the manufacturer (approximately 5-10 years).
Types of water pumps
Modern circulation pumps for heating boilers, in accordance with their design features, are divided into "dry" and "wet" models. Their differences are manifested in the nature of the interaction of the drive elements with the coolant.
Dry rotor units
The design of circulation pumps of this type does not provide for direct contact of the coolant with the engine rotor. Its working part is separated from the moving elements by specially designed rings. The latter are made on the basis of the following materials:
- graphite or ceramics;
- Wolfram carbide;
- classic stainless steel;
- aluminium oxide.
The principle of operation of the pump lies in the rotation of the blades in the coolant medium. In this case, the hole for the water intake is located in the center of the working chamber. The system of its outlet channels is located in the peripheral zone. Thanks to such a device, the working area is connected to the motor only through the shaft seal, which makes it possible, if necessary, to replace the electric drive without complete disassembly.
The advantages of dry-type pumping equipment include:
- high efficiency, reaching 70-80%;
- the minimum probability of water hammer at the time of launch;
- permissibility of vertical installation of the engine;
- the ability to pump significant volumes of liquid (due to high power).
Due to a number of disadvantages, dry-type units are used mainly in industry and in heating systems for office buildings. In residential buildings, the use is limited. Negative sides:
- high level of noise;
- the need for frequent replacement of O-rings;
- the possibility of leakage of the coolant in case of violation of the tightness of the chamber;
- the need for cooling the electric motor.
Due to their significant dimensions and weight, dry-type pumps are either installed directly on the floor or suspended on special brackets.
Wet rotor pumps
A heating system pump with a wet rotor is similar in principle to the model described above with one difference: the motor shaft is in contact with a coolant, which is simultaneously used to cool the engine. Such devices are not able to work without additional lubrication, in the absence of which they overheat and become unusable. Since all pump elements are a monolithic unit, its repair in the event of a failure is physically impossible. In this case, the product is completely replaced with a new one.
The advantages of units with a wet rotor include:
- noiselessness;
- compact size;
- low power consumption (no more than 30-50 watts);
- the ability to work without maintenance;
- low cost and easy installation.
The disadvantages of pumps with a wet rotor are limited power, the impossibility of eliminating a motor malfunction and a relatively low efficiency (40-60%). The disadvantages include the admissibility of installing the unit only in a strictly horizontal position.
Advantages and disadvantages of pumps
Previously, heating systems of various classes, as a rule, did not have a water pump in their composition. The coolant moved through the pipes by gravity, the continuity of the circulation was ensured by the pressure difference at different points of the circuit. Natural circulation systems are still used for heating private houses, although they are much less common.
The advantages of pumping systems with forced circulation include:
- reducing the load on the equipment by reducing the difference in temperature indicators in the inlet and outlet pipes;
- uniformity of heat flow distribution;
- the ability to adjust the temperature of the coolant;
- fast heating when starting a cold boiler.
To this should be added the possibility of integrating the pump into the system that controls the operation of the unit. Despite all the listed advantages, circulation devices are not without drawbacks, which appear depending on the power supply and high cost.
Features of marking water pumps
There are no uniform requirements for marking pumps of this class. Manufacturers themselves choose a set of technical parameters indicated on the nameplate of the device, which is attached to the case. It displays the following information:
- fixed direction of movement of the coolant;
- standard size (diameter) of abutting pipes;
- maximum pressure and temperature;
- product manufacturer and model;
- degree of protection and characteristics of the electrical network.
Sometimes the manufacturer indicates additional information - symbols that correspond to technical regulations, for example.
Rules for choosing water pumps for heating
It is possible to choose the right pump for heating systems only after a careful study of its technical characteristics:
- Efficiency or the ratio of the electricity lost in the pump to the useful work of moving the coolant;
- the value of the liquid head, which characterizes the pressure difference between the inlet and outlet openings;
- the maximum volume of the coolant in the system, pumped through the working chamber at the minimum resistance of the circuit (supply);
- power consumed by the device in kilowatts;
- nominal pipe diameter of the connected equipment.
Choose the right pump - choose the equipment specifically for the heating system, the medium temperature in which does not exceed 130-150 ° C. Attention is also drawn to the maximum pressure (PN) in the working circuit at 20 ° C and the period for which the manufacturer's warranty is given. Usually this information is enough to make sure that the pump characteristics match the parameters of the installed heating system.
Appliance power
This parameter depends on the heat output of the boiler equipment in which the pump is supposed to be installed. The latter is calculated on the basis of practical indicators sufficient to heat a room area of 100 sq. meters, for example. The more heat needs to be obtained from the heating system, the more powerful the pump must be to ensure the pumping of the required volume.
When selected, this parameter is taken with a small margin, guaranteeing the desired heat output. You should not save money and try to exactly comply with the calculated ratio of pump and equipment power. In the future, this can lead to much higher costs. It is also not recommended to buy a product with a large power reserve, which inevitably leads to excessive consumption of electricity.
Additional functionality
Before purchasing a pump unit suitable for boiler equipment, you should make sure that it has the following additional options:
- the ability to operate with a fixed speed of rotation of the drive shaft;
- admissibility to work in several modes (usually three speeds);
- the presence of an electronic control module.
These possibilities allow a more flexible approach to the use of pumping equipment in any heating network. In addition, they allow you to work in economical modes, which significantly increase energy saving indicators.
Installing the water pump
The most common way to install a water pump is to connect it to the jumper between the direct branch and the return (in the bypass). This approach provides the following benefits:
- convenience of dismantling or temporarily disconnecting the unit from the network in the event of problems with the power supply, for example;
- the ability to move the pump outside the heating circuit;
- exclusion of idling mode;
- admissibility of fine tuning of the entire system.
For installation, you will need a standard tool kit, including open-end and adjustable wrenches, pliers, as well as tow or linen thread and sealant.
Nuts of the "American" type, as a rule, are supplied with the pump, however, adapters (squeegees) and valves will have to be prepared by yourself.
Installation procedure:
- Three working assemblies with valves are assembled.
- Two of them are mounted on the sides of the pump, and the third is installed on a pre-measured section of a straight pipe.
- Before integration into the bypass, a pump loop is prepared, in which the nuts are not yet tightened.
- The places for embedding the units into the pipe are outlined, after which a professional welder conducts all the necessary welding operations.
- The lower part of the hinge is mounted on the return line, and then all the nuts are tightened.
At the final stage of work, the pump is connected to the power supply.
