Watts 174A-075 3/4 3/4 In Bronze Boiler Pressure Relief Valve, 75 psi, Threaded Female Connections

The 174A-075 is a bronze boiler pressure relief valve with a fixed 75 psi relief setting, so it opens at 75 psi and suits a system whose maximum allowable working pressure is at or above that. Note the valve's own maximum working pressure is listed at 56 psi and its maximum temperature at 250 degrees F. Match the relief setting to the boiler's MAWP on the boiler data plate before you install it.

Both ends are 3/4 inch female NPT: 3/4 inch inlet, 3/4 inch outlet, female threaded on each. That means it threads straight onto a 3/4 inch male NPT boiler tapping, and the discharge side takes a 3/4 inch male NPT nipple for the drain line. No adapters needed if your tapping is 3/4 NPT.

Pressure only. The 174A-075 relieves on pressure, with no temperature probe extending into the vessel. That is what a closed hot water heating boiler wants. If you are working on a domestic water heater, you need a T and P valve instead, one with a thermostatic element that also dumps on temperature. Do not substitute this one for a water heater T and P.

No. The 174A-075 is a bronze valve listed as not lead free, so it is for closed hydronic boiler service, not potable domestic water. Anywhere the water is drunk or drawn from a tap, you need a lead free certified valve.

The 174A series spans 30 to 150 psi across its settings, and the 174A-075 is the 75 psi member of that family. The setting is not field adjustable, so order the model whose setting matches your boiler's maximum allowable working pressure rather than trying to change one on the job.

Buy American Act compliance is recorded as USA on the 174A-075, which is what a federal, school district, or municipal spec is usually asking for on a hydronic boiler trim submittal.

Order by the model, 174A-075 3/4, which is the 3/4 inch 75 psi bronze valve. The valve itself is the whole part; nothing is bundled with it. On the job you will still need pipe dope or tape for the male NPT boiler tapping, and a 3/4 inch discharge line piped full size down to within a few inches of the floor with no valve in it. Nothing may reduce the 3/4 inch outlet.

The bronze body suits closed loop hot water heating, where it sees treated system water rather than fresh makeup, and it handles fluid to 250 degrees F. That covers normal hydronic supply temperatures with margin.