Checking the expansion vessel in a heat pump: pre-charge and signs of failure

The expansion vessel keeps the pressure stable as water expands and contracts.

Signs of a problem

Large pressure changes, frequent safety valve activation, or pressure drops when the system cools down.

Pre-charge check

The measurement is taken with the hydraulic side depressurized and in accordance with the manufacturer's procedure.

Correct setting

The pre-charge must match the static height and the filling pressure of the installation.