Weil-McLain GV-4 Overheating

Discussion in 'HVAC Heating & Cooling' started by joslinm, Dec 27, 2013.

  1. joslinm

    joslinm New Member

    Messages:
    22
    Location:
    Illinois
    Noticed some banging in the pipes near my boiler and discovered temp is up to 260 and still going higher. Shut of wall switch and restarted and seems to be fine now. What to check on and replace so this doesn't happen when I'm away for a week???
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    There are probably two different things that should have shut the boiler down, or not allowed it to get that hot in the first place: the aquastat may need to be replaced, as it is what tells the boiler when to turn on and off (other than the thermostat, but the aquastat sets the actual operating temps); and, it probably has an overtemp safety switch that should have shut the thing down when it got above the aquastat high limit setting by some amount.
  3. joslinm

    joslinm New Member

    Messages:
    22
    Location:
    Illinois
    I replaced the limit switch and set lower to 160 but still intermittently goes higher (220) with flame off


    Finally got video and audio of the thing doing what it does
    Not great, but you'll be able to hear (turn your sound up) and see temp
    http://www.youtube.com/watch?v=l3adlVi9pP0
    Lights top to bottom are
    Flame
    Pressure Switch
    Limit
    Circulator
    Power

    Temp gauge
    12 o'clock is 160
    1 o'clock is 190
    2 o'clock is 220
    3 o'clock is 250

    At 1:20 flame starts and temp goes up
    at 3:00 hits 160
    at 3:30 starts making gurgling sounds near rear where relief valve and circulator are
    at 3:45, 175-180 flame goes off - still gurgling
    at 4:00 hissing sound is from the vent - pressure is 20
    at 6:15 temp hits 220 even though circulator is still running
    at 8:20 circ goes off , still 220
    at 16:00 circ comes back on , now 225-230
    at 17:00 temp starts back down
    at 19:00 fan kicks on - temp is 160
    Gas and flame and operates and turns off normally


    Read more: http://www.************.com/forum/b...il-mclain-gv-4-overheating.html#ixzz2qwDc0PGN
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    You sure your circulator is actually pumping well? IF the water isn't moving fast enough past the burner, it can end up boiling.
  5. joslinm

    joslinm New Member

    Messages:
    22
    Location:
    Illinois
    thought that too, but why would this happen only a couple times a day at most?
    Just happened as I'm writing. The gurgling sounds like its from the expansion tank. The bottom is too hot to touch as is the inlet valve
    Last edited: Jan 20, 2014
  6. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,107
    Location:
    Houston, TX
    The way the temp keeps rising with flame off, would seem to indicate the lack of water movement, or lack of water.

    Are you sure the pump is running or are you going by the indicator ?

    At least the high limit seems to be working.


    Good Luck.
  7. joslinm

    joslinm New Member

    Messages:
    22
    Location:
    Illinois
    the indicator light.
    Might be worth a shot to change the circulator anyway as it's 20 yrs old?
    Hate throwing parts at it for nothing. I'd have somebody look at it but they wouldn't be able to reproduce the problem
    Thanks for the help, Mike
  8. DonL

    DonL Jack of all trades Master of one

    Messages:
    4,107
    Location:
    Houston, TX
    I agree about not throwing parts at it. 20 years is not that bad.

    Some of the old motor bearings could be lubricated.

    You can just feel it to see if it is running or overheating, when it does what it is doing.

    Intermittent problems can be a pain in the ass sometimes.


    Good Luck.
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