Hot water boiler pressure high

Discussion in 'Home Repair' started by MRnice, Nov 29, 2005.

  1. MRnice

    MRnice Guest

    My Dunham/Bushe residential boiler is a hot water boiler with a forced
    hot air central heating system. It has been running at a high pressure
    (30 lbs.) and this is causing the pressure relief valve to release
    water. I drained the expansion tank (which was full) by shutting the
    feed and opening the drain valve. It is an old system with no
    compressed air in the tank, which I believe does not have a bladder in
    the tank. It does have a shut off valve below the inlet to the tank
    and a drain valve with a hosecock connection on the opposite side. The
    inlet and drain are both on the bottom of the tank. After I drain it
    the system functions fine for a day until the pressure builds up and
    the tank is full again. I think I am bleeding it right, or am I? The
    pressure relief valve does go off due to the high pressure, but does
    seem to seat well after the pressure goes down. After reading some of
    the postings on the board, I also thought that the temperature setting
    on the aquastat may be too high. It is currently set at 160 as the
    high and 130 as the low with a 10 degree differential. What would the
    correct temperature setting be?

    I would appreciate any assistance. Thank you, MRnice
     
    MRnice, Nov 29, 2005
    #1
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  2. MRnice

    MRnice Guest

    I am emptying the tank again to make sure it is totally empty. I think
    air will enter through the drain valve into the tank, which should be a
    good thing if I understand how this tank works. I will look for a
    valve on the autofeeder, I know on a steam system it regularly fills
    which you can see in a guage glass. I am not as familure with Hot
    water systems. I guess too much water would push up against the
    pressure relief valve causing the 30+ lb. reading on the guage too. Of
    course, I know this is a more difficult fix. If I wanted to run the
    boiler without the feedwater regulator for a while, how often would I
    add water to the boiler? How would I know when it needs it? Thank you
    for your suggestion, it seems like the only other reason for high
    pressure. The stack is clean, relief valve seems to work only at
    preset 30lb. and the temp. is not too high. Do these boilers require
    any cleaning , chamber, etc.? I have changed the oil filter, replaced
    a bad ignitor last season (my first season in home), and cleaned the
    flame scanner eye as well as changed the nozzle. Could lack of prior
    maintenance have caused sediment buildup to produce a high stack
    pressure causing a problem? Thank you for your advice, Ron
     
    MRnice, Nov 29, 2005
    #2
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  3. MRnice

    MRnice Guest

    I also wonder if one of the tubes could be leaking inside the boiler.
    There is alot of water on the floor, but I thought it must be from the
    Pressure relief valve blowing down.
     
    MRnice, Nov 29, 2005
    #3
  4. MRnice

    Speedy Jim Guest

    MRnice wrote:

    > I am emptying the tank again to make sure it is totally empty. I think
    > air will enter through the drain valve into the tank, which should be a
    > good thing if I understand how this tank works. I will look for a
    > valve on the autofeeder, I know on a steam system it regularly fills
    > which you can see in a guage glass. I am not as familure with Hot
    > water systems. I guess too much water would push up against the
    > pressure relief valve causing the 30+ lb. reading on the guage too. Of
    > course, I know this is a more difficult fix. If I wanted to run the
    > boiler without the feedwater regulator for a while, how often would I
    > add water to the boiler? How would I know when it needs it? Thank you
    > for your suggestion, it seems like the only other reason for high
    > pressure. The stack is clean, relief valve seems to work only at
    > preset 30lb. and the temp. is not too high. Do these boilers require
    > any cleaning , chamber, etc.? I have changed the oil filter, replaced
    > a bad ignitor last season (my first season in home), and cleaned the
    > flame scanner eye as well as changed the nozzle. Could lack of prior
    > maintenance have caused sediment buildup to produce a high stack
    > pressure causing a problem? Thank you for your advice, Ron
    >


    Unless there is a leak, that boiler shouldn't need
    feed water except in rare cases.

    Oil-fired does need annual maintenance for cleaning
    and combustion air setting, etc. But that's not
    part of this problem.

    That has to be a cast iron boiler, so there are no tubes.
    Get the pressure under control and see if there is any
    evidence of leaks.
    Jim
     
    Speedy Jim, Nov 29, 2005
    #4
  5. MRnice

    Mark Guest

    if the expansion tank is filling with water when the system is in
    operation , then the tank has an air leak and air is leaking out,
    letting water in... then when the tank is full of water, the pressure
    will build excessivly when the water is heated..

    the air leak may be very small, like a tire with a small leak...



    Mark
     
    Mark, Nov 29, 2005
    #5
  6. MRnice

    MRnice Guest

    Each time I emptied the expansion tank, I opened the inlet valve and it
    seemed to fill. I closed the automatic feedwater regulator and the
    tank did not fill when I opened the inlet valve this time. I emptied
    the remaining water in the tank and put boiler on. My well water pump
    had a problem right before this happened and the water to the house was
    cut off for a while. Maybe some sediment ended up in the autofeed reg.
    when water was restored causing it to stay on. I think you hit it on
    the head with the feed water problem. Is there any way of cleaning the
    regulator to possibly repair it before going out and buying a new one?
    Thanks, Ron
     
    MRnice, Nov 29, 2005
    #6
  7. MRnice

    m Ransley Guest

    Auto feeds go bad and can be innacurate new. Turn it off and the
    supply, filling a boiler for my house is a once year deal, I have 3
    stories and keep 12-15lb cold. some systems need a bit more. Your
    pressure relief leaking is warning your pressure is to high, eventualy a
    boiler leak can develop. Im just a homemoaner here, no pro but I would
    call the manufacturer of the boiler and find out operating pressure
    guidelines, less is better for boiler life. I would wait till cool and
    drain water till its 15lb, keep the water fill off and see what happens.
    If you have 1-2 story house 15 may be not needed as I say I run 12-15 on
    a 3 story with boiler in basement, 4 levels, old and new boiler run the
    same. If no heat gets to upper radiators add a lb when Cold and bleed
    running. A too small an expansion tank can cause the same symptoms,
    increasing pressure when hot. Filling a boiler constantly is not good
    for a boiler as scale develops , reducing efficiency and life, if it
    knockc its got scale.
     
    m Ransley, Nov 29, 2005
    #7
  8. "MRnice" <> wrote in message
    news:...
    > My well water pump
    > had a problem right before this happened and the water to the house was
    > cut off for a while. Maybe some sediment ended up in the autofeed reg.
    > when water was restored causing it to stay on.



    If it is the same as my Watts fill valve and safety, it is a piece of crap
    and you toss it away. If it was sediment under the valve seal, it would
    probably be flushed out by now. My heater has had four Watts fill valves in
    25 years.
     
    Edwin Pawlowski, Nov 29, 2005
    #8
  9. MRnice

    MRnice Guest

    Thanks to you all for your advice. Everything seems to be fine so far
    with the feedwater valve closed. I guess I will just keep an eye on
    things.
     
    MRnice, Nov 29, 2005
    #9
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