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Boiler leaking at pressure relief valve

Hi...I'm obviously a newbie, so please bear with me...

With my system pressure at 11/12 psi, when I turn on the water supply (located on the other side of the pressure
reducing valve, which is set to 12psi), the system almost immediately goes up to 20psi and then slowly climbs. Then, when the thermostat goes on, it kicks up to over 30 after 10 minutes or so, at which point the relief valve starts leaking.

With the system back down to 12psi and the water supply off, when I turn on the thermostat it takes more time, but it again climbs up to 30+psi and starts leaking at the relief valve.

The expansion tank -- extrol #30 -- seems to not get ANY water in it. I know it won't slosh around audibly, but it's weight doesn't seem to change. When I checked the Schrader valve, no water came out. And,thus far, it seems there's NO pressure in it (though I do want to check if the issue is with the gauge I used).

So, I'm at a loss. Not sure whether it's the reducing valve that is leaking thru (I believe I had left the valve open continuously since I turned the system back on -- which I understand is a mistake) or whether the expansion tank is shot...or is somehow unable to take on the expanded water (could there be a block in the valve that controls access to the expansion tank?).

I'm at a loss here. Any ideas are appreciated, Mike

Comments

  • soot_seeker_2
    soot_seeker_2 Member Posts: 228
    Boiler system leaking at relief valve

    If you system gets to 30#, then the PRV isn't leaking, it's working! :-)

    The only way to check your expansion tank is essentially to disconnect it from the system and then pump it up to 12 psi and see if it holds. If you can't isolate it in place take care because a full tank is very heavy.


  • > If you system gets to 30#, then the PRV isn't

    > leaking, it's working! :-)

    >

    > The only way to

    > check your expansion tank is essentially to

    > disconnect it from the system and then pump it up

    > to 12 psi and see if it holds. If you can't

    > isolate it in place take care because a full tank

    > is very heavy.



    Yeah, the relief valve is working...the reducing valve (auto-fill?) may not be.

    As for the tank, it does have a valve there. WOuld I just close that valve and then pump it up to 12? Or, would I still have to take it off?
  • soot_seeker_2
    soot_seeker_2 Member Posts: 228
    Expansion Tank

    If you shut it off, do you have a way to to releive the water pressure? If you do, then that's easier. The key thing is that the water part of the tank shouldn't be under pressure when you are tryiung to set the air pressure.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Seems simply that

    the expansion tank is under-sized or the air charge is gone. I would get a compressor or bike pump and re-charge it to 12 psig cold.

    If that does not work, either replace the tank with a larger one sized for full system volume or purchase one or more additional tanks and connect them to the expansion line that exists.

    The tanks probably is full of water, -no sloshing and the heavy weight is the key. The Schraeder valve only affects gas pressure on the opposite side of the diaphragm from the water side. You will not get water out of it unless the diaphragm is ruptured.

    And if the Shraeder valve has no pressure it likely means that the air charge is gone, so pump it up first.

    If charging the tank does not solve it, it sounds like the system might be a converted gravity or large iron-pipe and radiator system with more volume than the average copper tube system.
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    If the tank is a diaphragm type

    Mike should not need to disconnect it to charge it. Bicycle pump or air compressor should do it. The Schraeder valve goes to the cushion side where the charge is held, not the water side.


  • The way I would try to relieve the water pressure from the expansion tank (again, not knowing if this is the CORRECT way) is to manually open the pressure relief valve. Is that what I should do?
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Not the relief valve

    but use the boiler drain.

    While you "can" use the relief valve you should not; that is not it's purpose. You could cause some debris to settle on the seat and it will drip, drip, drip.

    It is an emergency device and should be treated with respect :)


  • Thanks for all of your replies thus far.

    Pressurizing the expansion tank:

    The pressure in the SYSTEM is at 20 or so PSI right now (it had been up over 30, I turned the whole system off, and it went down there). Do I need to relieve the system pressure (via pressure relief valve) before I use the bike pump to pressurize the tank.

    Also, the valve going to the tank...open or closed to pump it?

    I do not think the tank has water in it. It's not at all heavy. Feels as empty as empty can feel.

    As for it being a converted gravity or large iron-pip and radiator system with more volume than the average copper tube system...I have no clue. All I can say is that the system had worked fine until I had shut it down for a few months to take off the radiators and repair some walls.


  • Yes, that seems obvious now. Will do so there. Shouldn't take much. Do I run into the problem of creating air in the system, though? WOuld I need to bleed the rads if I let too much out?
  • Brad White_9
    Brad White_9 Member Posts: 2,440
    If

    the tank is indeed a diaphragm type, there should be no air in the system itself. Letting water out will not automatically let air in. (System is under more pressure than the air surrounding it.). If you do get any air in and it goes to the radiators you can either bleed it out or know that they collectively act as some expansion cushion volume where ever they happen to be. (Air being compressible.)
  • Ron Schroeder
    Ron Schroeder Member Posts: 998
    mike

    Do your radiators look like steam radiators, and how big are the pipes connected to the radiators


  • I relieved the pressure via the drain...down to about 12. Tried to pump air into the expansion tank...won't take it. It was via bike pump and I was doing it with my hand, but I would have expected less resistance...
  • J.C.A._3
    J.C.A._3 Member Posts: 2,981
    Save yourself now...

    Call a pro. You're chasing your tail and possibly causing problems that could be costly.

    Try the link to the left "Find a Pro". Chris
  • Ron Schroeder
    Ron Schroeder Member Posts: 998
    need 0 pressure

    before pumping up tank and mak sure that vale is open
This discussion has been closed.