Watts 0556002 3/4 In Lead Free Self Closing Temperature And Pressure Relief Valve, 150 psi, 210 F, Extended Shank Up To 2 1/2 In Insulation

Yes. The 0556002 has a 3/4 inch male NPT inlet that screws into the heater's 3/4 inch T&P tapping, and a 3/4 inch female NPT outlet for the discharge tube. Inlet shank is 2-1/16 inches long, which is the extended shank version made to clear up to 2-1/2 inches of tank insulation, and the copper thermostat probe extends 2 inches into the tank.

It relieves at 150 psi or at 210 degrees F, whichever condition hits first. That is the standard residential and light commercial water heater setting, so it matches most tanks coming out of service. If your heater's data plate calls for a lower relief pressure, this is not the valve for that tank.

Depends on how thick the tank jacket is. The 0556002 carries a 2-1/16 inch shank so the copper probe reaches past insulation up to 2-1/2 inches thick and sits in the water, not in the foam. On a thin-jacket tank a short-shank valve is fine; on a heavily insulated or commercial tank a short shank leaves the probe buried in insulation and the valve will not sense water temperature correctly.

Size it by BTU input. The valve is rated 200,000 BTU/hr pressure discharge capacity and 105,000 BTU/hr temperature discharge capacity. The temperature rating is the one that governs on a water heater, so the heater's input rating has to be at or below 105,000 BTU/hr. Above that, you need a higher capacity relief valve.

The LF100XL body is a lead free copper silicon alloy, which is what puts the LF in the series name. That is the construction specified for potable hot water systems where lead free plumbing is required.

Yes on both. There is a manual test lever for the periodic exercise check maintenance crews run on water heaters, and the valve is self closing, so it reseats on its own once pressure or temperature drops back below the 150 psi / 210 F set points rather than staying open after a discharge.

It is a combination temperature and pressure valve, which is what code requires on a storage water heater. A pressure-only relief valve protects against overpressure but will not dump on a runaway thermostat; this one responds to either, using a 2 inch copper probe sensing tank water temperature at 210 F.

The 0556002 ships as the valve itself. You supply the discharge piping: 3/4 inch material threading into the female NPT outlet, run full size and terminated per local code. Thread sealant for the male NPT shank is on you as well.