The expansion vessel absorbs the change in water volume as temperature fluctuates, while the safety valve protects against excessive pressure.
Expansion vessel
It must have the correct volume and proper pre-charge relative to the total volume and static height of the network.
Safety valve
It must be suitably selected and equipped with a safe discharge path.
Common mistake
Incorrect pre-charging or an undersized vessel causes large pressure fluctuations between cold and hot system states.
