Watts 0163725 1 IN Bronze Automatic Reseating T and P Relief Valve, 150 psi, 210 degree F, Test Lever, 5 IN Ext Thermostat

The 0163725 has a 1 inch male NPT inlet, so it threads into a 1 inch female NPT T and P tapping on the heater. The outlet is 1 inch female NPT, which is where the discharge tube screws in. It is a water heater valve by design.

It relieves at 150 psi and at 210 degrees F. Those are the two independent triggers: pressure builds past 150 psi, or the water at the probe hits 210 degrees, and the valve discharges. Maximum working pressure is also 150 psi, so the tank it protects must be rated at or above that.

The extended thermostat probe is 5 inches of copper. That length is meant for tanks with thicker insulation or a deep tapping where a short standard probe would sit in the jacket instead of the water. If your existing valve has a short stub probe, a 5 inch element may bottom out or interfere with a dip tube, so measure the tapping depth before swapping.

Two separate capacities apply. On pressure relief it discharges 2,135,000 BTU per hour, and on temperature relief 500,000 BTU per hour. The temperature figure is the one that governs sizing against a water heater: the valve's temperature steam rating must equal or exceed the heater's input rating, so it covers heaters up to 500,000 BTU/hr input.

Yes. The 40L reseats on its own once temperature and pressure drop back below the 210 degree F and 150 psi settings, rather than staying open or needing replacement after a single discharge. A valve that keeps cycling open is telling you something upstream is wrong (thermal expansion with no expansion tank, or a failed thermostat), not that the valve is faulty.

The 0163725 ships as the valve alone. You supply the discharge piping, which threads into the 1 inch female NPT outlet and must run full size down to within a few inches of the floor or to an approved termination, with no valve or reducer in the line. Use an appropriate thread sealant on the 1 inch male NPT inlet.

It does. The 0163725 has a manual test lever so maintenance staff can lift and flush the seat on a routine inspection without pulling the valve. That is the feature institutional and MRO buyers want when the valve sits in a mechanical room on a PM schedule.

Bronze body, with a copper thermostat element, and it is manufactured in the United States. Bronze holds up in potable hot water service and matters on jobs with domestic-content requirements.