The expansion tank is an important part of the hot water heating system and the central air-conditioning waterway system. Its function is to accommodate and compensate the expansion and contraction of water in the system.

Generally, the expansion water tank is located at the highest point of the system, and is usually connected to the return water main pipe near the suction port of the circulating water pump (central air-conditioning chilled water circulating water pump).

The expansion tank is a steel plate welded container, there are various sizes of different specifications. The expansion tank is usually connected with the following pipes:

(1) Expansion pipe, which transfers the increased volume of water in the system due to heating and expansion to the expansion tank (connected to the backwater trunk).

(2) The overflow pipe is used to discharge the excess water in the water tank that exceeds the specified water level.

(3) The signal pipe is used to supervise the water level in the water tank.

(4) The circulation pipe is used to circulate the water when the water tank and the expansion pipe may freeze (at the center of the bottom of the water tank, connected to the main water return road).

(5) Sewage pipe for sewage discharge.

(6) The water replenishment valve is connected with the float in the box. If the water level is lower than the set value, the valve will be opened to replenish water.