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furnace white smoke

MyName2MyName2 Posts: 6Member
This seems new this year, but then the temp outside in north NJ is zero.

My neighbor has an oil furnace. I'm going to bet their tiny chimney has no steel lining. I see white smoke out of their chimney when the heating system is apparently on and the air above the chimney is shimmering.

Is this normal given how cold it is?


  • WeezboWeezbo Posts: 6,232Member
    edited January 2014
    the heat looks like water ,

    and the condensation looks like a cloud , and soot looks like a dark cloud ...

    did that help ?


    ok ,

    a stack fire looks like a red volcano , and an explosion looks like a stack airborn like a rocket with sonic diamonds shooting out the back end of it that turns to a red fire and then black smoke as it flys thru the air..

    thats all i know lol..
  • MyName2MyName2 Posts: 6Member
    No help

    No, Weezbo, that did not help. Pretty cryptic.

    When replacing my own oil steam boiler, I learned that white smoke was a bad thing, perhaps indicating a crack or hole in the boiler and steam was going out the chimney.

    I'm not sure about a hot water furnace, but am getting some feedback on other forums that it may indicate a bad mix of fuel/oxygen or a hole. Thought I'd ask here.
  • WeezboWeezbo Posts: 6,232Member
    edited January 2014
    condensate in the form of billowing white clouds

    is really easy to distinguish ..

    that usually means it is either running real cool or there is water in the stack ,

    if you open a firebox and it has a leak , you can usually see where the leak is coming from by different colours running down the side some where in the chamber...

    really bad leaks might be the sign of broken pins or gaskets not all leaks are easily repaired .

    white smoke itself is comes in different formations at different temps outside.

    it does not mean white smoke "You have a leak" by any stretch of the imagination.
  • JStarJStar Posts: 2,668Member

    Some water vapor is always present in the exhaust. Your neighbor can easily test his boiler for leaks by overfilling it and seeing if the water ends up on the floor or inside the boiler.
  • MyName2MyName2 Posts: 6Member
    temp perhaps

    JStar, I don't recall any white smoke from their house in the past. Another forum said worry about the white smoke if there is some when the temp is back into the 30's. When zero outside, white smoke is common. Monday it'll be warmer so I'll check then.
  • JStarJStar Posts: 2,668Member

    Agreed that white smoke is not always definitive in such cold weather.

    Does your neighbor have steam or hot water?
  • STEVEusaPASTEVEusaPA Posts: 2,862Member
    Why did you post this

    Why did you post this in 2 forums at the same time?
  • MyName2MyName2 Posts: 6Member

    JStar - My neighbor has a hot water furnace with oil as the fuel.
  • icesailoricesailor Posts: 7,265Member
    edited January 2014
    White Clouds:

    Its clouds forming from the water vapor in the exhaust or atmosphere. Like contrails (Condensation Trails) in the sky when jet aircraft pass overhead. Often when you hear a jet passing overhead, you see the plane and the trail making up a distance behind that grows to a large width at 35.000 feet.

    Water freezes at 39+ degrees F to -40 degrees. Ice melts at 32 degrees. Water vapor doesn't freeze in its separate components. Aircraft don't get wing/surface icing at +20 degree Outside Air Temperature (OAT) but might at +38 degrees from the drop in pressure over the surface and the drop in temperature. There will always be water vapor in exhaust. Whether there is a leak of water into the exhaust from a boiler needs to be looked at if the OAT is +32 or above. But if it is really cold and dry with wind from the NW with dry Polar air, it is almost always just clouds forming from the water vapor in the exhaust, being warmed in a small space above the flue. Just like direct vented Mod-Con boilers.
  • MyName2MyName2 Posts: 6Member
    thank you

    Thank you, icesailor. Great explanation.
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