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HOW TO CHOOSE A PUMP FOR CENTRAL HEATING

Modern boiler and heating equipment is designed for forced circulation of the heating medium in the pipe system. The circulation pump is an additional element in the network for this purpose. The main advantages of this system are the uniform distribution of heat in the room and energy savings by reducing the temperature difference between the forward and return flow of the pipe. With the right heating pump, you can guarantee efficient heating even in the harshest of cold weather and with the lowest possible energy costs.

PUMP DESIGN

When selecting a pump, it is necessary to take into account the design features of the heating system. Therefore, it is important to know the temperature range of the pump, the chemical composition of the coolant, the salinity of the water and the maximum pressure in the system. These parameters further influence the choice of materials for the impeller (noryl, bronze or stainless steel), for the pump housing and seals.


CONNECTION DIAMETER

If it is assumed that the boiler equipment and other heating system components are already installed, the diameter of the boiler inlet and outlet connection pipes must be selected according to their capacity in the boiler system.


PERFORMANCE

The capacity, or flow, of the heating pump (Q) is one of the basic parameters for the selection. In order to calculate it, it is necessary to know the heat consumption of the building (N), the specific heat capacity of the medium (c) and the temperature difference between the flow and return flow (δT), which is usually 20-35 °C. The calculation formula is as follows: Q = N / (s × δT).


The heat demand is determined by the construction of the building, the presence of window and door openings and additional thermal insulation. Standard values can be found in specialized reference books.


ELEVATION

In addition to its capacity to pump a certain amount of water per time unit, the heating pump must be able to provide the head required for the heating medium to overcome the resistance of the system. The following formula can be used for its calculation:



H = (R × L + Z) / ρ × g,


Where R is the specific resistance of the straight pipe section, L is the total length of the pipe (including "return"), Z is the total resistance of fittings and fittings, ρ is the density of the coolant, and g is the acceleration of gravity.


The hydraulic resistances of the system components can be found in the technical documentation. All elbows, fittings, valves, pressure regulators, valves and radiators must be taken into account.


Important: The above calculation algorithm is used when designing a heating system from scratch. To estimate the parameters of working networks, experts choose simplified methods.


POWER CONSUMPTION

Once the necessary data is obtained, the closest model in terms of characteristics is selected from the catalogue. It is important to remember that the calculated parameters are based on the maximum load during the coldest periods. For a large part of the heating season the demand for heat is not as great, so choosing a more powerful pump for heating will result in overconsumption of electricity.


Electricity consumption is the most important economic indicator of system performance. Most modern heating pumps are capable of operating in several load modes. The output is adjusted according to the outside temperature of the building.


In addition to manually regulated heating, there are fully automatic systems. These are additionally equipped with temperature sensors and frequency converters for the drive. They measure and analyse the heat demand in the room, on the basis of which the speed of the pump's impeller and, accordingly, the electricity consumption, are changed. The system is highly economical and does not require any operator intervention.


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