Watts - This 3/4 inch pressure relief valve is used in hot water boiler applications to protect against excessive pressure on all types of hot water heating boiler equipment. It consists of a iron body with forged bronze inlet, non-metallic disc-to-metal seating and stainless steel spring. This valve resists corrosive water conditions, sticking and freezing, and prevents water and sediment from being trapped in the seat. It is designed for emergency safety relief and should not be used as an operating control. The pressure setting is 30 PSI for applications up to 550,000 BTU/hr.