Watts 40L Automatic Temperature And Pressure Relief Valve

The Watts 40L Safety Relief Valve is a 3/4" automatic reseating temperature and pressure relief valve engineered to protect commercial hot water systems from dangerous temperature and pressure buildup in water heaters, storage tanks, and hot water distribution networks. It features a bronze body with 3/4" male NPT inlet and 3/4" female NPT outlet, and operates automatically to relieve excess temperature (210°F / 99°C) and pressure (up to 150 psi). The thermostat is copper with a Thermo-Bonded coating, and the probe length is 3" or 5" depending on model configuration; it includes a test lever and incorporates tamper-resistant bonnet screws and non-mechanical seat-to-disc alignment for reliable reseating. Designed for potable water service and direct-tank tapping mounting, it is commonly specified for commercial water heaters, hot water storage tanks, boiler support systems, and institutional or industrial facilities such as hotels, hospitals, schools, nursing homes, restaurants, laundries, and manufacturing plants to maintain safety compliance. This 40L valve adheres to commercial temperature and pressure relief service requirements and is compatible with common replacements like Watts 40XL-5 125/210 FS 3/4", Watts LF40XL-5 100/210 FS 3/4", and Cash Acme NCLX 3/4" in the same configuration.