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  1. #1
    Join Date
    Apr 2010
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    Default Fireplace and return air grill furnace location

    We just bought a house and the return air grill for the forced air furnace is within ten feet of this fireplace. I was told this application can create a negative pressure within this room when the fireplace and furnace are used together. This negative pressure may pull dangerous gases from the fireplace into the living area.

    What can I do to prevent this from happening?

    Find a grill in which the grill is facing the opposite way instead of down?

    I may not be able to relocated the intake grill.

    http://www.imagebam.com/image/9666d477976819/

  2. #2
    Join Date
    Jan 2010
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    Northern Virginia
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    Default Re: Fireplace and return air grill furnace location

    Add an outside air intake for the FP combustion, and glass doors.
    S_M
    Remove not the ancient landmark, which your fathers have set.

  3. #3
    Join Date
    Apr 2010
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    Default Re: Fireplace and return air grill furnace location

    Please excuse my lack of knowlege to fireplaces, I'm from Hawaii.

    I researched "sealed" glass fireplace doors. So you can have a fireplace wood burning and the glass door closed?

    Tell me this, when I start to get bids on replacing the fireplace what exactly do I ask?

    Add an outside air intake for the FP combustion, and glass doors?

    Thanks

  4. #4
    Join Date
    Jan 2010
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    163

    Default Re: Fireplace and return air grill furnace location

    [QUOTE=jgmc;193394]We just bought a house and the return air grill for the forced air furnace is within ten feet of this fireplace. I was told this application can create a negative pressure within this room when the fireplace and furnace are used together. This negative pressure may pull dangerous gases from the fireplace into the living area.

    What can I do to prevent this from happening?

    Find a grill in which the grill is facing the opposite way instead of down?

    I may not be able to relocated the intake grill.

    There may be no danger whatsoever. It is by no means a given that the room will be de-pressurized simply because the return grille is nearby.

    You can easily test for problems by: 1) Turn on the furnace and wait till it begins to blow air thru the registers. 2) Be sure all the supply registers in the fireplace room are open. 3) Next, build a small fire in the fireplace to see if the chimney drafts. (Be sure the damper is open.)

    Bear in mind that atmospheric conditions can affect how well a chimney drafts, so things could conceivably change from the day when you do the test. But, in effect, you will re-test every time you build a fire while the furnace blower is running.

    Any problem will become immediately apparent with a wood fire, because you can see and smell the smoke. The greatest danger from backdrafting is not from firepaces, but from gas appliances since they can give off odorless, invisible carbon monoxide.

  5. #5
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    Default Re: Fireplace and return air grill furnace location

    Quote Originally Posted by rdesigns View Post
    The greatest danger from backdrafting is not from firepaces, but from gas appliances since they can give off odorless, invisible carbon monoxide.
    Eh ?!?!?
    Carbon monoxide is produced whenever any fuel such as gas, oil, kerosene, wood, or charcoal is burned. Complete combustion of fuel products results in the production of carbon dioxide, which is generally harmless. Incomplete combustion results in the production of carbon monoxide.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  6. #6
    Join Date
    Jan 2010
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    163

    Default Re: Fireplace and return air grill furnace location

    Quote Originally Posted by canuk View Post
    Eh ?!?!?
    Carbon monoxide is produced whenever any fuel such as gas, oil, kerosene, wood, or charcoal is burned. Complete combustion of fuel products results in the production of carbon dioxide, which is generally harmless. Incomplete combustion results in the production of carbon monoxide.
    Of course--but CO does not separate itself from the flue gases and air that carry it. Wood smoke, oil smoke, etc. are easily recoginized in any quantity that might contain harmful levels of CO.

  7. #7
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    Default Re: Fireplace and return air grill furnace location

    Just pointing out all fuels give off carbon monoxide and can be just as harmful. Your orginial post wasn't clear and implied only gas fired equipment could be a source of harmful CO.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  8. #8
    Join Date
    Apr 2010
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    14

    Default Re: Fireplace and return air grill furnace location

    It is gas but we were not planning on using the ceramic logs currently in there plus the chimney itself needs to be rebuilt so maybe adding glass doors and vents will help.

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