hello tia, look at tyhe btu ratting , I think it will be fine make sure its over but not under. ( the new pressure and temp valve. )

A boiler uses a pressure valve. The tag attached to the PRV implies that the valve should be installed with the rubber seal in the horizontal position.

Once foreign particles get on the seal, it may not seal up again. It's probably why many techs won't touch the valve.

If you have the proper isolation valves on your system, it's an easy job. If not, you have to work fast.

Depending upon what's in your boiler water, a valve could fail after the first blow-off, or last 30 years.

You should try to determine what caused the pressure to rise to the level that would open the valve in the first place. It's unlikely a two year old valve would start leaking on its own.

Isn't the PRV spring loaded? Once the pressure is released, it should close and seal. In this case, when I flipped the test valve, the "plunger" pulled out but was not pulled back in. I think the spring is shot.

I doubt its actualy due to high pressure, more likley the PRV has failed on its own. The only other thing could be the supply side pressure reducer failed and is allowing to much pressure into the system.

Unfortunatley, there is no pressure gauge on the system to check. I may place a pressure gauge over a boiler drain and open the drain just to check the pressure is OK.

I can isolate the boiler from the zones so repair is not an issue for me. Just a threaded 3/4 connection, so thats easy.

No pressure gauge? Interesting.

Your expansion tank could be out of air, or full of water or your domestic water coil, if used, could have a pinhole leak in it.

You must have gotten some contaminant in the stem of the PRV. They are indeed spring loaded.

The stem moves in and out pretty freely which makes me think the spring has failed. I will look at the expansion tank and put a gauge on the systems to monitor.

I always thought there should be a gauge on the system. I will look into cutting one in. There are other oddities to this install too. For example, the expansion tank sits under the air seperator. Then the water feed enters between the expansion tank and seperator. This prevents me from removing the expansion tank without cutting pipes.