Watts® 174A Boiler Pressure Relief Valve, 3/4"Used in hot water heating and domestic supply boiler applications to protect against excessive pressures on all types of hot water heating supply boiler equipment. It consists of a bronze body construction with NPT threaded female inlet and NPT threaded female outlet (drain) connections, non metallic disc to metal seating, stainless steel spring, and test lever. Series 174A resists corrosive water conditions, sticking and freezing, and prevents water