Cascade control of two or more heat pumps: how the load is shared

In larger installations, multiple heat pumps can operate in cascade so that total capacity is adjusted to the load.

Lead and lag units

One unit starts first and the following are added when demand increases.

Rotation

The controller can rotate the priority unit so that operating hours are shared more evenly.

Part load

The cascade allows for better adjustment when the load is smaller than the total installed capacity.

Basic requirement

Proper hydraulic layout and common control logic for temperature and flow are required.