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  1. #1
    Join Date
    Jun 2005
    Posts
    4
    New guy here, hello all!

    Anyway, built a new home in Chicago IL. I had a g51, 90% lennox unit installed. But the contractor did not plum the fresh air intake tube to the outside of the house. It just terminates directly outside the unit in the basement.

    Question: Should you run the fresh air intake outside for better performance?

    My basement is about 1400sqft with 10ft ceilings. Anything else you guys need to know?

    Thanks for any direction you guys can give me!

    [Edited by nofear95 on 06-09-2005 at 07:51 AM]

  2. #2
    Join Date
    Jun 2005
    Posts
    4
    TTT

  3. #3
    Join Date
    Apr 2003
    Location
    Eugene, Oregon
    Posts
    1,209
    The defining factor is Lennox installation instructions. They will tell you how the 2-pipe system must be installed.
    Proud supporter of Springfield Millers and Oregon Ducks.

  4. #4
    Join Date
    Mar 2004
    Posts
    1,042
    I haven't seen the instructions, so I don't know the manufacturer's policy. In general, it will be more energy efficient if it is connected outside, unless the basement is already super-drafty or has a dedicated air intake serving the furnace area.

    Right now you're using air from inside the basement for combustion. Once the furnace is blowing that air out, it will be replaced by cold outdoor air leaking in through building penetrations, etc. If the basement were very drafty, it might just make the basement colder than it would be otherwise. If the furnace is in a mechanical room in the basement with is a fresh air intake duct in the room providing air for combustion (for the water heater and furnace), it'll just make that part of the basement colder than it would be otherwise. If you don't have either of those, the forced combustion process will put the house under negative pressure. With that negative pressure, cold air is going to weazel its way in around every penetration in the building's insulation in order to replace all the air that the furnace uses to support the flame. That means more drafts, less comfort, and less efficiency.

  5. #5
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,765
    pretty sure the G51 and G61 can be used as one or two pipe systems. we never have and never will install as a one pipe system due to chemicals and dirt in indoor house air. also since you are sucking house air for combustion house will be draftier.

  6. #6
    Join Date
    Jun 2005
    Posts
    4
    Thank-you all for your input. I will hopfully get the contractor back out to finish the job.

  7. #7
    Join Date
    Mar 2005
    Location
    Suppy NC
    Posts
    4,517
    G-51 can have a one pipe system. exhaust to the out side and intake with a 90 degree albow faceinf down with a short piece of pipe off it and a supplied plastic screen

  8. #8
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    Yes it can be piped outside and I would recommend it. Preferably using a concentric kit so you only have one wall penetration. Makes a better job, and prevents depressurizing the living space. Any air removed from the home for combustion must be replaced via leaks in the envelope.
    There is nothing more frightful than ignorance in action....Mark Twain

  9. #9
    Join Date
    Jun 2005
    Posts
    4
    I'm expecting a call back today. Worst case Ill do it myself. Just regular PVC right.

  10. #10
    Join Date
    Mar 2002
    Location
    Richmond, Virginia
    Posts
    4,264
    Not a very good diy job. Too many pitfalls.
    There is nothing more frightful than ignorance in action....Mark Twain

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