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Thread: Intake/exhaust

  1. #1
    Join Date
    Jul 2005
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    171
    For a direct-vent gas furnace in a basement, assuming the intake and exhaust PVC pipes are penetrating the outside wall side by side, what is the proper way to terminate them? I have seen every possible combination.

    Is there a code provision that says the exhaust has to be so high off the ground, pointed in such and such direction, etc? Same for intake.

    If there is no code requirement, what is best practice?

  2. #2
    Originally posted by dx
    If there is no code requirement, what is best practice?
    To follow the manufacture's recommendations.

  3. #3
    Join Date
    Jun 2005
    Posts
    347
    trane has a good looking termination the bayvent200. it dosnt have any piping out of the home and its low profile.

  4. #4
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    Jul 2005
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    171
    Jultzya, are you saying there is no code requirement, or are you saying you don't know?

  5. #5
    I'm saying that there are specific installations instructions for the equipment you are installing.

    1.) Follow them.

    2.) Make sure the installation is according to the current IMC.

  6. #6
    Join Date
    Jan 2002
    Location
    East Grand Forks, MN
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    1,373
    Follow the manufacturer's installation manual, because it also follows the Mech code, except for those special cities that require extra rules, then you have to follow their rules.

  7. #7
    Join Date
    Jul 2005
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    171
    Guys, I'm not installing anything. And I'm not planning on it either. I'm a contractor but NOT an HVAC contractor.
    I just see a lot of houses with the intake and exhaust done in such a way that a lot of exhaust is going to get sucked into the intake.

    I'm just curious as to what the mech code is for distance between intake and exhaust, orientation, distance from ground, etc.

    If you can't answer the question, please refrain from giving the tired old answer to follow instructions.

  8. #8
    Join Date
    Nov 2000
    Location
    Eastern PA
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    68,852
    DX, the answers are being given accurately. Most local codes are determined by the specific requirements of the individual manufacturer of the furnaces. Municipal inspectors look at the installation instructions of the furnace and make sure that the termination is as per that instruction manual.

    If any, and it does not take a lot, vent gases are being brought back into a furnace through the combustion air piping, the furnace will shut down.

    As long as vent gases have the oportunity to rise away from the combustion air inlet there will be no flue gases entering the combustion air.

    Another one of the rules of physics that applies to all two pipe terminations is that the vent and combustion air terminations must be within a certain distance from one another, usually 12-14 inches. This is to make certain that these two pipes are in the same pressure zone for proper vent/combustion air operation.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  9. #9
    Originally posted by dx
    I'm a contractor but NOT an HVAC contractor.
    If you can't answer the question
    If you were in HVAC, then you would understand that your question has several factors and required distances.

    EVERY manufacture is a little different.
    EVERY location is a little different.

    You have to look at the home in front of you to make an informed decision on where and how those pipes are going to be run and terminated.

    It's just not that simple Bud!

  10. #10
    Join Date
    Feb 2004
    Posts
    2,597
    i'm guessing dx is a home inspector.

  11. #11
    Join Date
    Nov 2000
    Location
    Eastern PA
    Posts
    68,852
    Ya gotta admit; having all of those different termination configurations does seem silly.
    Government is a disease...
    ...masquerading as its own cure…
    Ecclesiastes 10:2 NIV


  12. #12
    Join Date
    Jul 2005
    Posts
    171
    Yes, aside from the obvious hack jobs, every installer seems to have his own idea of what's good. My own house has it with the exhaust pointing down toward the ground and the intake about 18" above it and pointing away from the house. This is per the Carrier manual that came with it and makes logical sense. You want the two separated as much as possible and the intake higher so it doesn't suck up dirt. Not quite sure of the logic for other configurations, but I guess if there isn't a code requirement, anything goes.
    Robotek, as far as inspectors "look at the installation instructions", maybe on your planet, not around here. Here a good inspector is considered one who can tell a lineset from water pipes.

  13. #13
    Join Date
    May 2004
    Posts
    368
    dx, where is around here at? you don't have a location filled in on your profile.
    There are codes in place for the termination, however, the manufacturers instructions take precedence in this case since the mfg. had the system tested and listed under this configuration.
    As an inspector I never approve an installation without verifying the venting per the instructions and furthermore, not any inspectors I know of in my area would either. This is planet Earth, State of Michigan, under the IRC with Michigan amendments. Maybe on Pluto they dont check the instructions, then again maybe the inspectors there aren't State/Planet Registered.
    Vern P: 2003 MBC,MRC,IFGC,IFC
    An HVAC-Talk Michigan Chapter Mechanical Inspector, Jurisdiction-Ann Arbor

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