Watts 0275832 1 1/4 In Bronze Boiler Pressure Relief Valve, 90 psi, Threaded Female Connections

Yes. The 0275832 has 1-1/4 inch female NPT on both the inlet and the outlet, so it screws onto a 1-1/4 inch male NPT boiler tapping or nipple. Because the outlet is also female threaded, you pipe the discharge line to it with a male-threaded 1-1/4 inch nipple and run it full size to within a few inches of the floor.

Match the relief setting to the boiler's maximum allowable working pressure. The 0275832 is factory set to relieve at 90 psi, which suits a high pressure or commercial hot water boiler rated at or above 90 psi. A typical residential hydronic boiler is rated 30 psi and needs a 30 psi valve instead. The 174A series is offered across a 30 to 150 psi range, so a 90 psi valve on a 30 psi boiler would let the vessel go far past its rating before opening.

4,011,000 BTU per hour at its 90 psi setting. Size by capacity, not just pipe size: the valve's rated discharge has to equal or exceed the boiler's gross output, or the vessel can overpressure even with a correctly set valve on it.

Pressure only. The 174A 0275832 protects against overpressure and has no thermostatic element, so it is not a substitute for the T and P valve required on a water heater. Use it on boiler applications where the code calls for a pressure relief valve; for a domestic water heater you need a T and P valve with a temperature probe.

Yes, the 0275832 comes with a manual test lever. That matters for MRO and facility crews because relief valves on boilers are normally exercised on a schedule, and the lever lets you lift the disc off the seat to verify it is free without pulling the valve.

No. A relief valve has to see boiler pressure at all times, so nothing that can isolate it may go between the valve and the vessel. Thread the 0275832 directly into the boiler tapping using its 1-1/4 inch female NPT inlet, keep the valve upright, and leave the outlet piping unvalved and unreduced from the 1-1/4 inch outlet.

250 degrees F is the maximum temperature rating. That covers normal hot water and low pressure steam boiler service. The body is bronze, which is what lets it sit in continuous hot water service without the corrosion problems of a plain iron body.