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  1. #1
    Join Date
    Aug 2007
    Location
    Kelowna BC Canada
    Posts
    21

    Combustion air intake

    My new gas furnace is direct vent, my old furnace was not. Do I still need the old combustion air intake that is tied into the return air system?
    Thanks

  2. #2
    Join Date
    Sep 2007
    Location
    Maryville Tennessee
    Posts
    92
    Explain a little more or some pics.

  3. #3
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,013
    Are you sure it was for combustion air? It could be ( seeing as it's connected to the return air)
    fresh air make-up for the entire home.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  4. #4
    Join Date
    Aug 2007
    Location
    Kelowna BC Canada
    Posts
    21
    it is a 4 inch duct with 1/4 inch screen. What is it and do I still need it?
    Thanks so much
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  5. #5
    Join Date
    Aug 2007
    Location
    Northern VA 38 degrees N by 76 degrees W
    Posts
    5,060

    Exclamation Not sure what codes;

    are used in Canada, but in the U.S. it would be a clear code violation. You have what appears to be a fresh air intake directly next to your furnace exhaust which is allowing your by- products of combustion to be drawn back into the house and distributed. I would have your installer come back and correct the defficiency right away.

  6. #6
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,743
    if it is tied into return air you need it if the house is built tight.

    if you do keep it it needs to be moved away from furnace exhaust as stated before.

  7. #7
    Join Date
    Jun 2001
    Location
    Louisville, KY
    Posts
    12,189
    Quote Originally Posted by DBarker View Post
    it is a 4 inch duct with 1/4 inch screen. What is it and do I still need it?
    Thanks so much
    Are you feeling sleepy?
    Perhaps you should have read the instructions before calling.

  8. #8
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by DBarker View Post
    My new gas furnace is direct vent, my old furnace was not. Do I still need the old combustion air intake that is tied into the return air system?
    Thanks
    If it was tied into your return it was not a combustion air intake. Disconnect it and see if your windows start condensating
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

  9. #9
    Join Date
    Aug 2007
    Location
    Kelowna BC Canada
    Posts
    21

    Smile Good stuff!

    The installer left a file with all the documentation for the installed equipment. I looked at the furnace install document to see what it said about clearances between intakes, I need to know if the old intake is considered "mechanical".
    See direct vent clearances, item J and K.
    I have already plugged it off untill this CO2 thing is cleared up. The furnace has not yet ran, except for testing at start up, as the heat pump is doing the job.
    This forum is very good.
    Thanks all
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  10. #10
    Join Date
    Jan 2007
    Location
    Mn the state where absolutey nothing is allowed
    Posts
    1,351
    first: second opinion is right,it needs to be moved away from the new furnace vent
    second: no mater if its mechanical or passive the question to ask is there other gas appliances in the home??? a gas water heater still needs air.

  11. #11
    Join Date
    Aug 2003
    Location
    Lincoln, Nebraska
    Posts
    1,051
    It looks lioke a fresh air for you entire house but couldn't tell for sure. The fresh air here in Nebraska must be 10' from any exaust. I am sure that your codes wqould say somthing like this. The installers should have known this as it could be very dangerous. Do not run the furnace until this is fixed.

    Was this done by a reputable HVAC company?
    Its a good Life!

  12. #12
    Join Date
    Dec 2000
    Location
    Michigan
    Posts
    724

    Hmm Make-Up and or Combustion Air Intakes

    DBarker

    Here are my recommendations:
    Cover the "Make-Up Air" intake on the outside.
    (Note if the duct is connected to the return it is Make-Up Air not Combustion.)
    Call your City/local HVAC inspector to review the two vents After they confirm one of them must be moved, move the furnace exhaust as it is easier.
    Then uncover the Make-UP Air Intake
    Then use the hole in the wall if you have a gas water heater, to install a Combustion Intake by using a dryer vent with the flapper-removed by running the duct down the wall into a five-gallon pail.
    Now sit back and be safe and warm with your new furnace, a Make-up and a Combustion Air Intake!
    The quality of my performance, sometimes depends on the quality of my audience.
    Imitation (Plagiarism) is the best compliment one can get -- "Open A Window"

    To improve Indoor Air Quality: Control Indoor Air QUANTITY = "I.A.Q.Q."

  13. #13
    Join Date
    Apr 2002
    Posts
    11,808
    Quote Originally Posted by DBarker View Post
    The installer left a file with all the documentation for the installed equipment. I looked at the furnace install document to see what it said about clearances between intakes, I need to know if the old intake is considered "mechanical".
    See direct vent clearances, item J and K.
    I have already plugged it off untill this CO2 thing is cleared up. The furnace has not yet ran, except for testing at start up, as the heat pump is doing the job.
    This forum is very good.
    Thanks all
    I never saw the photos before. Your old intake is a mechanical intake. You probably need 6 to 10 feet of clearance from the furnace vent/combustion air intake.

    If you block off the vent now, you could notice a rise in winter humidity levels to the point that your windows condensate.

    If you used to run a humidifier all winter with the old furnace, maybe your house leaks enough to keep RH down.
    The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.

    http://www.ductstrap.com/

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