Watts 174A-90 1 1/4 1 1/4 In Bronze Boiler Pressure Relief Valve, 90 psi, Threaded Female Connections

Both ends are 1-1/4 inch female NPT on the 174A-90. Inlet and outlet are the same size, so it threads straight into a 1-1/4 inch tapping on the boiler with a nipple, and the discharge side takes 1-1/4 inch pipe run down toward the floor. No adapters needed if your boiler tapping is 1-1/4 NPT.

It is factory set at 90 psi and that setting is fixed, not field adjustable in the sense of picking a new number off the valve. Maximum working pressure of the system is listed at 68 psi, so the boiler operates below the setpoint with margin. The 174A series as a whole spans 30 to 150 psi settings, so if your boiler is tagged for a different maximum allowable working pressure, order the 174A at the setting that matches the boiler nameplate rather than this one.

Steam discharge capacity is 4,011,000 BTU per hour at 90 psi. Size the valve so its rated discharge is at or above the boiler's gross output; if your boiler input exceeds that figure, you need a larger valve or multiple valves.

No. The 174A-90 is not lead free, so keep it on closed boiler and heating loops. Anything touching potable water needs a lead free rated valve instead.

250 degrees F maximum. That covers normal steam and hot water boiler service. The body is bronze, which is what gives it the corrosion resistance for continuous boiler-side mounting.

Watts 174A series, model 174A-90 1 1/4, manufacturer part number 275832. Two things have to match on a replacement: the pressure setting stamped on the old valve and the pipe size. This one is 90 psi with 1-1/4 inch connections both ends.