Pressure relief valves are installed in residential water systems to reduce and stabilise inlet pressure from the water mains supply, which is generally too high and variable for domestic appliances to function properly. These valves can also be used to control inlet pressure to domestic hot water storage. Essentially a safety valve, the device is installed directly on to the hot water heater or piping.
Too much pressure in a system puts unnecessary strain on water heaters, plumbing joints, and taps and washers. This increases the chance of leaks, burst hoses on washing machines, and potential damage to other appliances. It also adds greatly to water hammer problems. Hot water pressure relief valves are used to reduce the incoming pressure on hot water heaters, so that they are not damaging any of the internal parts of the heater, and to extend the lifespan of the hot water system.
In the event that the thermostat on the hot water heater system fails, and the unit continues to heat, the hot water pressure relief valve allows water to be released – acting as a vent. As pressure and temperature rise, the valve will activate, preventing the possibility of pressure building dangerously and forcing the unit to explode. It is normal for the valve to drip during a water heating cycle, or during very hot weather. This simply shows that the valve is doing it’s job.
Manufacturers generally advise a hot water pressure relief valve replacement every 5 years. This is important, as correct operation is vital for safety reasons, and the warranty may also be affected if parts are not updated. Manufactures also recommend that the valves are activated every 6 months to check for blockages and to ensure correct function is maintained.