Water shut-off valve
Reliance Europe

Expansion Control Valves (ECVs) are fitted to the cold water inlet to water heater, downstream of the inlet non-return valve. The ECV acts as the relief valve in the system.

The ECV is always selected to be a lower pressure setting than the mandatory P&T Relief valve, so that as the water heater goes through a heating cycle, the ECV relieves the resulting expansion of water to the drain line. As the ECV is fitted to the cold water inlet, the water relived to drain will be cold. If no ECV is fitted, the expansion control is catered for by the P&T Relief valve which relieves hot water to drain. The ECV does not have a temperature probe fitted to it and operates in response to overpressure only.