boiler equiepments

What is a circulator pump?

پمپ سیرکولاتور خطی

In this article, the following questions about the circulator pump will be answered.

Definition of circulator pump
Where is the circulation pump installed?
What are the main parameters for choosing a circulation pump?
What are the executive recommendations for installing a circulation pump?
Circulating pump

The word “Circule” means to rotate.

Circulating pump refers to pumps that are responsible for moving or circulating cold or hot water in the air conditioning or central heating systems of the building from the place of production to the places of heat exchange in cooling and heating devices.

In other words, after providing hot water in the building’s central heating boiler. And also the supply of cold water in the cooling cycle of the chiller and the cooling system of the building. Circulator pumps are responsible for the flow of this hot water or cold water in pipes such as radiators, fan coils and air conditioner coils.

Water circulation pumps for cooling and heating systems in small and medium-sized buildings usually have linear and ground types and 1450 round. And compared to similar water supply pumps, they have less electrical power.

Basically, circulation pumps are used only to circulate the water of the cooling and heating system in the circuit of these equipments.

Therefore, water is riding on their impeller and they do not need to suck water from lower levels (such as irrigation and water supply pumps).

Circulator pump installation location

Circulating pumps are usually installed in the return water circuit of cooling or heating systems.

In other words, they are placed before the central heating boiler in heating systems and before the chiller in cooling systems.

So that the water output of the circulator pumps in the heating systems enters the boiler. Then it is distributed in radiators and fan coils.

And in cooling systems, the circulating pump water enters the evaporator of the chiller and then enters the fan coils and air conditioner coils.

In order to return the unused hot water in the hot water piping of the building, it is necessary to install the hot water return pump before the coil or double wall source on the hot water return pipe.

The main parameters for choosing a circulation pump

The amount of head and flow of water in circulation required by the system

Linear or ground pump

Circulator pump brand and model

Pump motor power and speed

Gear / flange connection

The diameter of the inlet and outlet pipes of the circulation pump

Executive recommendations for installing a circulator pump

It is better to separate the function of the hot water boiler circulation pump of the heating (or cooling) system of the building, with the circulation path of the hot water feeding the boiler in the coil source, for each of the two paths, for better exploitation in different seasons of the year, a separate circulator pump should be installed.

In general, the off-on operation of the circulator pumps is done by the wall thermostat installed on the return water pipe of the heating (or cooling) system.

The temperature setting of the wall thermostat installed on the suction pipeline of the circulator pump should usually be about 5 degrees Celsius lower than the set temperature of the submerged thermostat of the building’s hot water boiler.

It is necessary to install a strainer in the suction pipe of all pumps and install a shock absorber in the inlet and outlet pipes of ground circulator pumps.


One of the most important and decisive factors in the correct calculation of the required head or pressure of the circulator pump is to pay attention to the gravity and natural flow of water inside the vertical pipes of the heating and cooling system of the building.

This means that the only function of circulator pumps are used only in closed cooling and heating systems.

It compensates for the frictional pressure drop of the water flow along the pipes, fittings, valves and coils of the cooling and heating system of the building.

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