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Gas boiler smell

Boston_2 Member Posts: 107
We just purchased a house with an older gas hot water boiler.  It has a standing pilot and i noticed that there is a slight smell in the boliler room.  If i put my nose near the vent of the bioler i can smell that it's coming out of the boiler.  It's not a gas smell.  It's hard to put my finger on it.  I have a smoke/CO detector in boiler room and nothing is going off.  I had a chimeny guy come and check the draft and he said it was fine.  I also called a plumber and he said it seemed ok.  My old steam boiler had electronic ignition so maybe this is a standing pilot thing.  I also noticed that there is little draft when the gate (not sure what it's called) is closed.  When i start the boiler and things get going the smell goes away.

Thanks for your help.


    STEAM DOCTOR Member Posts: 1,564
    Auto damper

    Check your auto vent damper. There should be a hole in the "flap". This allows the products of combustion from the pilot to escape up the chimney.
  • Boston_2
    Boston_2 Member Posts: 107
    Vent Damper

    How would i go about checking that? Do i need to take the damper off?
    STEAM DOCTOR Member Posts: 1,564

    Remove vent damper or vent pipes connected to the damper. Wear a pair of thick gloves. Some of these vent pipes are razor sharp. The vent pipes or vent damper might be screwed in.
  • JStar
    JStar Member Posts: 2,752
    edited August 2013

    You should also be able to see the damper from the draft diverter that is underneath. No need to remove the damper.
  • Boston_2
    Boston_2 Member Posts: 107
    Smell update

    So i shined a light up into the diverter and i can see there is a hole about the size of a quarter, so i think that is what you are refering to.  I took the pilot and pilot tube out and cleaned everything with a wire brush, made sure the very small pilot hole was clear, put it back to gether nice and tight.  The pilot is much stronger now and everything is working great, but if i put my hand below the diverter i can feel the heat from the pilot coming out the bottom and i can still smell something. It is not a gas smell.
  • kcopp
    kcopp Member Posts: 4,095
    Did a bird or a squirell....

    fall down the chimney and die? wouldn't be the 1st time....
  • RJ_4
    RJ_4 Member Posts: 484

    Sounds like it may be a flue draft issue,  is there fresh air into boiler rm , check to make sure the boiler rm is not in a negative pressure, neg. press. can be caused by bathroom exhaust fans and open boiler rm doors.  check to make sure flue cap is in place and the correct type, on a lot of old boilers it took a few minutes with the main burner on to create a draft up the flue. If your smell goes away after boiler fires that indicates flue draft.   check to see if there is any old soot build up,  you may be smelling this, hard to tell without being in the rm. I would call in boiler pro
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