The central air conditioning system.

In the central air conditioning system, the cold water pump, the heating water pump and the hot water circulation pump run almost continuously according to the building’s operating hours. These three water rings have different characteristics so one type of pump should not be chosen in common.

closed and open systems.

The cold water circuit is a closed system: the pump just needs to win the loss of the pipe, the heat exchange line and the valve, the NPSH is often excessive. The heat circuit through the tower is the open system, it is necessary to add the static pressure column to the tower and the pressure at the suction door when the tank water level is low.

Volume of shift.

The modern chiller allows for reduced flow by load. Combining the inverter with the two-way valve controlled by the branch end voltage difference helps to significantly reduce the pump power, as long as the flow is kept as minimal as required by the chiller and the pump.

Choose a pump with real pressure.

Many systems exceed the loss and then choose the pump too large, forced to save flow with the valve.Calculate the actual loss, select the working point near the BEP and use the frequency inverter to fine-tune.

Noise and vibration.

• Use soft joints, anti-vibration stands or inert stands for large pumps.
• The speed of 1.450 rpm is more than 2,900 rpm if the flow allows.
• In-line pumps such as GD, KGP help with the compact layout in the technical room, but need enough straight pipes at the suction door.