Boiler pressure high, pressure relief valve leaking

daveb1111

So I decided to work on my boiler this fall and although I learned a lot through the process and from this site, I have hit a wall. I have a New Yorker Vertical Tube Boiler, Model#AP-690, its about 25 +/- years old. I started working on my boiler because my coil gasket look old and crusty, I replaced it.

I never really paid attention to the pressure relief valve before or the pressure gauge, so it might have been leaking before, but I figured I'd replace it because it looked old and rusty. I replaced it with the same specs. as old one, the boiler got up to temperature, pressure went over 30 psi. and leaked.

I then read that maybe my expansion tank may be waterlogged, although the old seemed fine according to a "tapping" test, the bottom 2/3 sounded hollow while the upper 1/3 sounded full. Given it be an inexpensive cost, I replaced it with the same specs, EX-30. I also replace the air vent above it. The pressure still went to over 30 psi and leaks out the pressure relief valve.

I then read that most professionals when they replace the pressure relief valve, they will replace the Ex. tank and pressure reducing water inlet valve, because they all might go bad at same time. I have a house pressure of 35 psi. from a well, so i thought that maybe the old reducing valve was leaking. I replaced it with the same spec., which drops it down to 15 psi. The boiler pressure again went above 30 psi. and leaked again.

I'm not sure what to do now, looking for some advice. I was thinking maybe I'm not bleeding the air from my system properly. I've been bleeding my baseboards, is there a better way? Is there any other part that would contribute to high pressure if failed? Any help would be much appreciated!

p.s. -The aquastat was set at about 190F. Hi - 170F. Lo, with Diff. at 15.

MikeL_2

Dave,
If your boiler is equipped with a dhw coil it's possible for the coil to have a small leak that would try to raise the boiler vessel pressure to match your domestic water pressure.....

daveb1111

Yeah I do have a dhw coil, is there a way to isolate or troubleshoot a coil?

Jamie Hall

daveb1111 said:

Yeah I do have a dhw coil, is there a way to isolate or troubleshoot a coil?

Trace out your domestic hot water. There should be a shutoff valve between the cold water lines and the boiler. Try closing that and see what happens -- but! Also open a hot water tap somewhere in the house when you do! This will do two things -- relieve the pressure as the boiler heats up (hot water expands) and will check that the shutoff valve really shut off. Old ones sometimes don't...

daveb1111

Ok I shut off the cold water going into my boiler, turned the hot water on the faucet and a really slow stream is coming out. When I turned the cold water back on, I left the hot water on the faucet and brown water came out at first.

Jamie Hall

Oh great. I think you may well have a leaking domestic hot water coil in that boiler...

EBEBRATT-Ed

sounds like it to me

daveb1111

I think so too, I isolated the incoming and outgoing of the coil and so far no pressure increase. I'll give it the night with it isolated and see if it leaks. Thanks so far, I'll keep y'all posted

daveb1111

So after about twelve hours with the boiler on and the coil isolated, the pressure is around 22psi and the relief valve didn't leak once. Now I have to find a replacement coil

EBEBRATT-Ed

here you go