Surecal 24 litre Expansion TankSurecal 24 litre Expansion Tank Expansion Tanks are an essential feature on any hot water system. They need to be installed on the hot water supply after the hot water heater. Anywhere on the hot side of the system, but preferably as near to the hot water heater as is reasonably possible. It can be fitted in any orientation. The tanks are pre set at our factory for most systems, however the pressure is worth checking as some installations are set up