HPNR Valves

RMC’s High Pressure Expansion Non-Return (HPNR) Valves are suitable for coil type heat exchange water heaters. The valve is a combination non-return and pressure relief device. The non-return prevents the backflow of hot water into the mains supply. The relief valve prevents an over-pressure condition within the coil.

High Pressure Expansion Non-Return Valves limit the maximum pressure in a system by relieving excess pressure to the drain line and are classified as a functional control for this type of application. HPNR Valves should only be installed on the cold or inlet installation on a water heater as the valve is primarily intended to cope with the excess pressure generated during a normal heating cycle.

RMC’s HPNR Valve is available in a 15 mm configuration.


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Size Description Catalogue Number
15mm Unrestricted HPNR503