Our brass valves has the function of both a check valves and a pressure relief valves On the a hand, it is a check valves that prevents the hot water from flowing back from the boiler into the cold water circuit , on the other hand, the pressure in the boiler rises on the set value when heating water for any reason, the water heater pressure relief valves as a valves dissipates the required water, serious disturbances and dangerously overpressure Make of brass, has a highly density, is strong and enduring and has a high resistance to mechanical damage and wear and tear The dimensions are 1 / 2inch male thread and 1 / 2inch female thread Brass valves automatically releases excess pressure to water heater explosions The valves can be used both in a house and in an apartment as well as in most commercial rooms in areas such as industry, sanitary, heating, Manufacturer: RGYBAO