Diagram of connecting the expansion tank

Connection scheme for the expansion tank to the heating system should include:

A shut-off valve - for disconnecting the tank from the system and checking the initial pressure in the gas cavity.

A drain valve - for draining water from the tank.

A pressure gauge to monitor the pressure at the point of connection of the expansion tank.

A safety valve - to protect the heating system from emergency pressure exceeding the maximum allowable value.

Expansion tanks for heating systems are used in buildings with autonomous sources of heat and in buildings connected to the heating network using an independent scheme.

The expansion tank is connected before the suction nozzle of the circulation pump, and there should be no elements that introduce significant hydraulic resistance between the connection point of the tank and the pump. This connection scheme ensures a stable excess pressure in the heating system, regardless of the thermal and hydraulic regimes.

The connection is made using detachable connections, as during operation, it may be necessary to disconnect the tank for repairs.

Another feature of membrane expansion tanks is the increase in pressure in the heating system with increasing water temperature. Therefore, the tank should be designed so that at maximum water temperature, the pressure does not exceed the maximum allowable value, and at minimum temperature, it does not become less than the pressure necessary to fill the heating system. To avoid pressure fluctuations in the heating system with temperature changes, an expansion tank can be installed, the pressure in the gas cavity of which is maintained by a compressor.

Expansion tank for a boiler is necessary only if the boiler is connected to a closed circuit that is not connected to the atmosphere. It protects the boiler and the connected heating or hot water supply system from pressure exceeding the maximum allowable value. Low-power boilers (up to 30 kW) are usually equipped with expansion tanks as standard, while for boilers with higher power, they need to be selected separately.

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