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  1. #1
    Join Date
    Apr 2003
    Posts
    469
    Is it a bad idea to reuse a chimney for an over the range vent hood?

    I now have a 90+ furnace and electric water heater.
    So the old chimney is blank'd off.

    The old chimney is round sheet metal surrounded by what looks to be concrete.

    Its about 10' long, and about three feet to where the back of the range hood would be.

    I would put in some type of damper to prevent backdraft.

    The range hood would be 200-300 cfm.


    Thanks

  2. #2
    Join Date
    Mar 2004
    Location
    SE Michigan
    Posts
    17,911
    Woowoo, I wouldnt recomend it. You may get a ton of grease in there.
    " Kill a Commie for Mommy! "

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  3. #3
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,741
    have a chimney guy take a look at it. unless you deep fry a LOT of food grease in a household kitchen should not be a problem. make sure range hood has decent filters in it.

  4. #4
    Join Date
    Apr 2003
    Posts
    469
    Just to clarify.
    This is a residential $100-$200 range hood.


    The house was originally built with an oil burner,then converted to gas.
    Both forced air

  5. #5
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,741
    doubt a cheap hood will have enough power to blow exhaust up the old chimney. better get it looked at.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,913
    I can see the grease fire already.

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  7. #7
    Join Date
    Apr 2003
    Posts
    469
    Originally posted by beenthere
    I can see the grease fire already.

    I am not sure why?
    The only thing that would be vented into it is the new range hood.

    I did a little snooping last night.
    It's a 10" metal flue
    Range hoods usually vent with a 6" or 7" duct.

    I am planning on buying a hood with a filter/trap built in.

    I just want to avoid cutting another hole in the roof.


    And yes, I am an engineer

  8. #8
    Join Date
    Nov 2005
    Location
    PortChester N.Y.
    Posts
    135
    An engineer? Then you already know the answer!

  9. #9
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,741
    Originally posted by beenthere
    I can see the grease fire already.


    if he is going to have a grease fire at least it will be in a metal flue surrounded by concrete. better than some 30 gauge range venting. its a household kitchen, not a chinese restaraunt hood.

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    67,913
    Velocity?

    Without rechecking the book, I think new code for commercial hood duct is 1800 FPM.

    They discovered at 1200 FPM the grease didn't make it out of the duct system.

    I kow he's talking about his house, but when he goes into that 10" liner, his velocity will be so little that it will collect at the bottom. It won't go up the chimney.

    Thats why they use smaller duct.

    Anybody thats ever changed a motor on a exhaust unit for a kitchen knows how greasy the fan gets, and knows what i'm talking about.

    PS: A grease fire in the liner will crack the motar from the heat. And nothing says the damper will stop the heat from igniting the grease on the hood.


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