Expansion tanks

In a sealed heating system water expands as it heats up, and the extra volume has to go somewhere — otherwise the pressure rises and the boiler safety valve opens. An expansion vessel takes up the excess water and returns it to the system as it cools.

Here you will find GWS HeatWave vessels for boilers and radiators and SolarWave vessels for solar systems, where the fluid runs hotter. A simple sizing rule: the vessel volume is 10–12% of the water in the system; a 24 kW boiler with radiators usually needs 24–35 L.

See the detailed calculation and connection diagram in “Heating expansion vessel”.