Watts 100XL-8-150210 3/4 3/4 In Brass Self Closing Temperature And Pressure Relief Valve, 150 psi, 210 degree F, Test Lever, 8 In Extension Thermostat

The 100XL-8-150210 has a 3/4 inch male NPT inlet and a 3/4 inch female NPT outlet, so it screws into a standard 3/4 inch NPT T&P tapping and takes a 3/4 inch NPT discharge pipe on the outlet. Shank length under the inlet threads is 1.1875 inches.

The 8 inch copper probe reaches past the tank wall insulation and jacket into the water itself, which is what a side-tapped or heavily insulated commercial heater needs so the element senses actual tank temperature instead of the jacket. A short-shank valve dropped into the same opening can sit in dead space and fail to sense an overheat. Pick the probe length to match how deep the tapping sits on your tank.

Match the heater's BTU input to the valve's relief capacity: this one is rated 200,000 BTU per hour on pressure discharge and 105,000 BTU per hour on temperature discharge. The temperature number is the one that governs on a water heater, so it suits heaters up to 105,000 BTU/hr input. A larger boiler or heater needs a higher capacity valve.

No. The 100XL-8-150210 is a brass body valve that is not lead free, so it should not go on a potable water system in jurisdictions enforcing the lead free rule. For domestic hot water service, specify a lead free T&P valve instead.

They are two different numbers and both matter. The valve is set to discharge at 150 psi, while its listed maximum working pressure is 94 psi, meaning normal standing system pressure should stay well below the relief point. If your system regularly sits near the relief setting, you have a thermal expansion or pressure regulation problem to fix upstream rather than a valve selection problem.

It is flagged Buy American Act compliant with USA origin, which is what a government, school district, or federally funded institutional job needs on the submittal. Order it by Watts part number 66110, model 100XL-8-150210 3/4.

Four things pin a 100XL down: connection size (3/4 inch NPT here), relief pressure setting (150 psi, out of a 75 to 150 psi range), temperature setting (210 degrees F), and thermostat probe length (8 inches). Miss the probe length and you get a valve that threads in fine but senses the wrong spot. The full callout for this one is 100XL-8-150210 3/4.

Yes, the 100XL-8-150210 comes with a manual test lever, which is how maintenance staff exercise the valve on a periodic check to confirm it lifts and reseats. Facility maintenance programs and most plumbing codes expect a T&P valve you can manually test in place.