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white smoke from chimney

REMREM Member Posts: 10
I saw white smoke from my chimney and my tech opened the flu and we did not see any steam coming from the flu after the boiler was hot and running. I was afraid of a cracked heat exchange, I have had this happen to me 2x before ( don't know why and only after about 10 years of use. This boiler is a weil-mcclain and it is in use since april 2006. the batting around the inside of the boiler is dry. could this just be normal due to the cold air and the hot steam hitting it? any other suggestions?

Thanks in advance.

ps. any one that has not read it should read Dan's book on steamheat. I bought it a few years ago and it has been very helpful.

Thanks Dan!!!


  • Bob HarperBob Harper Member Posts: 732
    is it steam?

    Look at the flue gas outlet of the chimney. If you see a gap then the white plume, it is steam and not "smoke".

    One of two things come to mind:

    a) your heat exchanger is cracked leaking water into the combustion chamber or

    b) you just elected a new Pope
  • REMREM Member Posts: 10
    white smoke from chimney

    New pope is not till next week!!!

    We didn't see any smoke or steam coming out of the furnace going up the chimney from the inside. It was very white, I am thinking steam I am hoping steam. There are no other indications that the boiler is cracked. Just hoping for someone to tell me this is normal. I noticed it on my neighbors chimney also, don't know what kind of heat that have. mine is gas.
  • SWEISWEI Member Posts: 7,356
    I have had this happen to me 2x before

    in the same house?  That is not normal.
  • JStarJStar Member Posts: 2,668

    A little white smoke is okay on startup, as long as it goes away.

    Weil McLain will tell you that their boiler never leaks....cough....

    Something must be causing it to happen. Do you add water very often? Any vents leak?
    - Joe Starosielec
    [email protected]
  • Charlie from wmassCharlie from wmass Member Posts: 3,922
    the steam will be clear until cooled

    what boiler and what fuel are you using? The steam is not visible until it is cooled to water vapor. As asked are you using much water?
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • REMREM Member Posts: 10
    white smoke from chimney

    smoke is just seen when heat is coming up after being off.

    automatic water feed was coming on too often...the "Bell" screen was clogged. we got that cleared up and the the furnace was back to normal but I was still noticing the white smoke.  It seems to be ok now but that smoke thing is bothering me.    
  • REMREM Member Posts: 10
    white smoke from chimney

    Weil/Mclain and natural gas steam heat/radiators
  • John MillsJohn Mills Member Posts: 767
    Sounds normal

    Big byproduct of combustion is water vapor so common if cold out to see white steam coming out of the flue pipe of a gas product. More when first started, once things warm up it will decrease. If mild and dry, may not be visible. Cold and damp, really noticable and may never stop being visible. 
  • Jamie HallJamie Hall Member Posts: 6,701
    A certain amount

    of white smoke from the chimney is quite normal -- particularly on days when it is cold, but the humidity is relatively high.  Combustion creates a good bit of water vapour, and when it hits the cold air it condenses.  If the humidity is high enough, you will see it -- but it should evaporate again and disappear into the air pretty fast.

    Beyond a certain amount, however, and you have a leak...  The question is, of course, how much is too much?  And the only really good way to answer that is to keep an eagle eye on your water level in the boiler -- which, hopefully, you have been doing.  If it starts dropping faster than it used to, that's a potential problem and should be followed up.  On the other hand, if the water usage is just as it always has been, I'd say not to worry... much...

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-McClain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • REMREM Member Posts: 10
    white smoke from chimney

    thank you all for the info.

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