Watts 100XL-125210 3/4 IN Brass Self Closing Temperature and Pressure Relief Valve, 125 psi, 210 degree F, Test Lever, 4 IN Ext Thermostat

Yes. The 100XL-125210 has a 3/4 inch male NPT inlet that threads into the heater tapping, and a 3/4 inch female NPT outlet for the discharge line. Shank length is 1.1875 inches, so the thermostat probe seats past the tapping wall on a standard 3/4 inch T&P opening.

The 100XL-125210 is set to relieve at 125 psi and 210 degrees F. Maximum working pressure on the valve is listed at 94 psi, so the system it protects should operate below that, with the 125 psi setting as the relief point.

The 100XL-125210 uses a 4 inch extended copper thermostat probe. That length is for tanks with thick insulation or a jacket where the tapping sits well outside the water, so the probe reaches the stored water. On a heater with a shallow tapping a short-shank T&P is the correct choice instead, since a 4 inch probe would bottom out or sit too deep.

No. The 100XL-125210 has a brass body and is not a lead-free valve, so it is not suited to potable water systems in jurisdictions enforcing lead-free requirements. For potable hot water service under those rules, specify a lead-free T&P relief valve instead. This valve suits non-potable and hydronic style applications where lead-free is not required.

Discharge capacity on the 100XL-125210 is 200,000 BTU per hour on pressure relief and 105,000 BTU per hour on temperature relief. Size against your heater's input rating: the temperature relief figure is the limiting number, so the heater input must not exceed 105,000 BTU per hour.

Both. It is a combination temperature and pressure relief valve, so it opens on either a 125 psi pressure rise or a 210 degree F water temperature. A straight pressure-only relief valve will not protect against a runaway thermostat, which is why code requires T&P protection on storage water heaters.

Yes, the 100XL-125210 is supplied with a test lever and is a self-closing design, so a maintenance tech can lift the lever to flush the seat and confirm the valve reseats. That matters on MRO schedules where annual T&P testing is part of the routine.

No. The relief setting is fixed at 125 psi and the 100XL family covers 75 to 150 PSI settings across models, so a higher-pressure system needs the 150 psi version rather than this one. The setting is not field adjustable.

It is listed as Buy American Act compliant, country of origin USA, which is what a government, school, or healthcare procurement spec usually needs on the submittal. The orderable part number is 100XL-125210, Watts part 66090.

The outlet is 3/4 inch female NPT, so the drain line threads in at 3/4 inch and must be carried full size to the termination point with no reduction and no valve in the run.