A non-return valve, abbreviated to NRV, is a valve that prevents flow reversal in a pipe, protecting pumps, boilers, water heaters and supplies from contamination or damage. UK NRVs are manufactured to BS EN 13959 and are widely used on shower pump installations, boiler circuits, central heating circulating pumps and water meters. They are also used in submersible pumping stations to keep the rising main full and prevent backflow into the wet well. Spring loaded, swing and ball check designs are all available, with installation orientation governed by the design type. NRVs should be selected for the duty and inspected periodically as part of routine plumbing maintenance. Failed NRVs can cause noisy operation, water hammer and unwanted mixing of hot and cold supplies at mixer taps.
Non-return valve (NRV)
Valve preventing flow reversal in a pipe to protect pumps and supplies.
