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Weil Mclain - Pressure Keeps Building

Help : (

And thanks in advance!

OK, so over the last week the boiler's pressure keeps increasing to above 30, which causes the release valve (i believe thats then ame) releases the extra water and spits water into thee coffee can i have, and then some.

Whats weird (to me) is that I have the water from the city turned off right before the inlet valve, and have the inlet valve loosened as to not allow water to fast fill even if the valve from the city to the boiler was open or is leaking.

Also what i noticed, i think, is the expanison tank seems to be filling immediately. I have emtpited it twice in the last day and as soon as i turn the valve back on before the tank, it seems to fill right away.

Any help for trouble shooting and/or resolving would be greatly appreciated.

I can also post pics ifthat would be helpful.


I have attempted to empty the system to see if it keeps filling and it won't empty, for the last 20 minutes there has been a constant slow drain coming out of the boiler.


I am pretty sure i can hear water going through the inlet valve, i tried my best to put my ear up against it. I can hear a hissing sound, I am guessing is running water going through it.

The valve right before the inlet valve is turned off ,so not sure if i am hearing correctly.

Gonig to shut the main water off and see if it stops.

UPDATE 3: OK, shutting off the main has stopped both the inlet valve from making the slight hissing noise (water running through it) and when i opened the valve to drain the boiler, the slow drain stopped completely.

So, by doing this it seems i have discovered that both the valve before the inlet valve and the inlet valve are bad?

Reason i am thinking that is if the valve prior to the inlet valve is off, then no water should even be getting to the inlet valve.

And, with the inlet valve's top nut/screw thing completely loosened, it shouldn't allow any water to pass, correct?

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  • Pressure Problems

    Your expansion tank sounds fine.  If you drain it and then fill it, you will hear water going in and it should stop when 2/3 full.

    I would replace your inlet valve with a ball valve and install a good pressure reducing valve.  Caleffi makes the best PRV.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • jeffcravener
    jeffcravener Member Posts: 10
    pressure is getting to me

    I was just about to post that i think what I am calling the inlet valve is real y called a [u][color=#0066cc]Automatic water feeder[/color][/u]?

    But not sure.

    I agree that i think the inlet valve is part of the problem, but the pressure reducing valve seems to be working fine, whever the boiler gets to 30 psi, it releases water...which is good for the boiler, but bad for the basement : S
  • bill_105
    bill_105 Member Posts: 429
    My Bet!

    If you have a tankless coil or indirect, you're now in the market for a new one!
  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 3,931
    edited January 2011
    That one

    is your pressure relief valve and yes, it's working fine.

    The one I'm talking about can be called an automatic water feeder, pressure reducing valve or just the feed valve.  They fail often, sometimes in the closed position, sometimes in the open position.

    Bill said you may have a leak in your tankless coil.  Do you have one of these or do you heat your domestic hot water separately?
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • saber
    saber Member Posts: 9
    water logged

    I had this happen years ago when i drained the system to move a radiator to repair the floor. When i refilled it i got to much water in the system. Even with the pressure at 10 psi it would heat up and increase the pressure and pop off. I drained the expansion tank, bleed the air out and run the system until the pressure stayed at 10 to 13 psi. during run time.
  • jeffcravener
    jeffcravener Member Posts: 10

    just making sure iam getting the linog down ; )

    The boiler heats both the house as well as the hot water used for the sinks and shower.
  • jeffcravener
    jeffcravener Member Posts: 10

    want to make sure iam understanding the directions for the feeder valve.

    It has a thumbscrew at the top. Screwing it all the way down tight should do a fast fill for the bolier, correct? And when it is lossened all the way up, it is then set for automatic, letting water in only if the pressure is lower than a certain amount, correct?

    When it is working correctly, of course.
  • Domestic

    What Bill is saying may be true then.  You either have a tankless coil in your boiler or a separate hot water tank with a heat exchanger inside.  One or the other may have a leak, allowing high pressure from your domestic side to flow into the hydronic side, lifting the relief valve.

    What part of the country are you from?  Do you have a heating professional you can call? This might be over your head.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • jeffcravener
    jeffcravener Member Posts: 10
    the reason i ask...

    ...to gill the boiler back up, does it need to be on or off?

    I am trying to fill it back up and stop it when it reaches 12 psi (while cold) but it doesn't appear to be filling up.
  • jeffcravener
    jeffcravener Member Posts: 10

    eatern PA. I am hoping to be able to fix without calling someone as I am pretty sure i wouldn't be able to afford paying someone to fix it.
  • jeffcravener
    jeffcravener Member Posts: 10

    def don;t have anything separate...i can follow the pipes from the boiler to both the radiators and the hot water for the sinks/shower.

    So, if it is leaking from inside, one chamber to another, is that something that can be fixed or does that mean replacement?
  • You can

    have it fixed by replacing the tankless coil if that's the problem.  This is only a guess on our part.  Have someone look at it to be sure, someone with experience with boilers and tankless coils.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
  • jeffcravener
    jeffcravener Member Posts: 10

  • jeffcravener
    jeffcravener Member Posts: 10

    ...boiler? It doesn't seem to be filling back up.

    Am I missing a step?
  • World Plumber
    World Plumber Member Posts: 389
    Feeder valve

    The screw in the top usually controls the pressure, many of the valves have a lever to bypass the regulator part and fast fill. The valves tend to rust when sitting then when they open won't close and over pressurize the system or they just won't open.

        Sounds like you need to replace the feeder valve and the valve before it. I would replace the valve before it with a ball valve. Turn your main back one and listen for water running into the boiler. If you don't hear anything fill the boiler and close the ball valve for a few days and see if the pressure holds.

        Where you at in Eastern PA. I'm in the Wilkes Barre region.
  • jeffcravener
    jeffcravener Member Posts: 10

    .....the coil was leaking, wouldn't I have the problem all year round, and not just starting now?

    I would think the water from the city would be passing to the boiler at all times.
This discussion has been closed.