174A Watts Water Pressure Relief Valve Model: M1, 1", BTU/HR Rating: 3,100,000Watts Series 174A Boiler Pressure Relief Valves are 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