How to install a circulation pump

In heating systems with forced or natural circulation put circulating pumps. It is needed to increase heat dissipation and to adjust the temperature in the room. Installing a circulation pump is not the most difficult task, with a minimum of skills you can manage on your own, with your own hands. 

What is a circulation pump and what is it for?

A circulating pump is a device that changes the velocity of a fluid without changing the pressure. In heating systems is put for more efficient heating. In systems with forced circulation, it is an obligatory element, in gravitational ones it can be set if it is required to increase the thermal power. The installation of a multi-speed circulation pump makes it possible to change the amount of heat transferred, depending on the temperature in the street, thus maintaining a stable room temperature.

Circulation pump in section

Circulation pump with wet rotor in section

There are two types of similar units - with a dry and wet rotor. Devices with a dry rotor have a high efficiency (about 80%), but they make a lot of noise and require regular maintenance. Units with a wet rotor work almost silently, with the normal quality of the coolant can pump water without failures for more than 10 years. They have a lower efficiency (about 50%), but their characteristics are more than enough for heating any private house.

For a selection of the circulation pump for heating systems, read here.

Where to put

It is recommended to install the circulation pump after the boiler, up to the first branch, but on the supply or return pipeline it is all the same. Modern aggregates are made of materials that normally tolerate temperatures up to 100-115 ° C. There are few heating systems that work with a hotter coolant, so considerations of a more "comfortable" temperature are untenable, but if you are so calmer, put it back.

Can be installed in the return or straight pipeline after / before the boiler before the first branch

Can be installed in the return or straight pipeline after / before the boiler before the first branch

There is no difference in the hydraulics - the boiler, and the rest of the system, it does not matter at all whether the pump is in the supply or return branch. What matters is the correctness of the installation, in the sense of tying, and the correct orientation of the rotor in space. Nothing else matters.

There is one important point in the place of installation. If in the heating system two separate branches - on the right and left wing of the house or on the first and second floor - it makes sense on each to put a separate unit, rather than one common - directly after the boiler. And on these branches the same rule is kept: immediately after the boiler, until the first branch in this heating circuit. This will give the opportunity to set the required thermal conditions in each part of the house independently of the other and also in two-story houses to save on heating. How? Due to the fact that the second floor is usually much warmer than the first and there requires much less heat. If there are two pumps in the branch that goes up, the velocity of the coolant is set much less, and this allows you to burn less fuel, and without compromising the comfort of living.


There are two types of heating systems - with forced and natural circulation. Systems with forced circulation can not operate without a pump, they can not work with a natural pump, but in this mode they have a lower heat output. Nevertheless, a smaller amount of heat is still much better than its total absence, therefore, in areas where electricity is often cut off, the system is designed as a hydraulic system (with natural circulation), and then the pump cuts into it. This gives high efficiency and reliability of heating. It is clear that the installation of the circulation pump in these systems is different.

All heating systems with warm floor forced - without a pump through such a large circuit coolant will not pass

All heating systems with warm floor forced - without a pump through such a large circuit coolant will not pass

Forced circulation

Since the heating system with forced circulation without a pump is inoperative, it is installed directly into the opening of the supply or return pipe (of your choice).

Most problems with the circulation pump are due to the presence of mechanical impurities (sand, other abrasive particles) in the coolant. They can jam the impeller and stop the motor. Therefore, in front of the unit necessarily put a screen filter-mud.

Cutting the circulation pump into a forced circulation system

Installing the circulation pump in a forced circulation system

It is also desirable to install ball valves on both sides. They will enable you to replace or repair the device without draining the coolant from the system. You block the cranes, take off the unit. Only the part of the water that was directly in this piece of the system merges.

Natural circulation

Circulation of the circulation pump in gravity systems has one essential difference - a bypass is necessary. This is a jumper that makes the system workable when the pump is not running. On the bypass put one ball shut-off valve, which is closed, all the time while pumping is working. In this mode, the system operates as a forced one.

Scheme for installing a circulating pump in a system with natural circulation

Scheme for installing a circulating pump in a system with natural circulation

When electricity is lost or the unit breaks down, the crane on the jumper is opened, the cock leading to the pump is closed, the system works as a gravitational one.

Mounting Features

There is one important point, without which the installation of the circulating pump will require rework: it is required to rotate the rotor so that it is directed horizontally. The second point is the flow direction. On the body there is an arrow indicating the direction in which the coolant should flow. So, turn the unit so that the direction of the coolant movement is "along the arrow".

The pump itself can be installed both horizontally and vertically, only when selecting the model, see that it can work in both positions. And one more thing: with a vertical arrangement, the power (created head) drops by about 30%. This should be taken into account when choosing a model.

Connection to power supply

Circulating pumps operate from the 220-volt network. Connection is standard, a separate power supply line with automatic protection is desirable. For connection, three wires are required - phase, zero and ground.

Scheme of electrical connection of the circulation pump

Scheme of electrical connection of the circulation pump

The connection to the network itself can be arranged using three-pin sockets and plugs. This type of connection is used if the pump is connected to a connected supply line. It can also be connected via the terminal block or directly to the terminals with a cable.

The terminals are located under the plastic cover. We remove it, having unscrewed some bolts, we find three connectors. They are usually signed (pictured N - zero wire, L - phase, and "earth" has an international designation), it is difficult to make a mistake.

Where to connect the power cable

Where to connect the power cable

Since the whole system depends on the efficiency of the circulation pump, it makes sense to make a redundant power supply - put the stabilizer with the batteries connected. With such a power supply system, everything will work for several days, as the pump itself and boiler automation "pull" electricity to a maximum of 250-300 watts. But at the organization it is necessary to calculate all and to select capacity of accumulators. The disadvantage of this system is the need to ensure that the batteries are not discharged.

How to connect a circulator to electricity through a stabilizer

How to connect a circulator to electricity through a stabilizer

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