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  1. #1
    Join Date
    Mar 2008
    Location
    albany, new york
    Posts
    20

    need advise on venting furnace

    I have a three story building with an 80% furnace on each floor. The owner wants to replace the 80s for 90s. there are buildings attached to both sides of the building i'm working in. The back of the building is 30 feet or so from the furnances. Can I vent directly up to the roof like the 80s are or do I have to go the back of the building?

  2. #2
    Join Date
    Mar 2001
    Posts
    1,213
    You need to read the manual for the make/model/size you are installing, plus your local codes & AHJ opinion.

  3. #3
    Join Date
    Mar 2008
    Posts
    59
    How would you get up through the roof? If it is through the chimney you will need to insulate the exhaust but it can be done it should be in the manual.

  4. #4
    Join Date
    Oct 2006
    Location
    Northwest NC
    Posts
    70
    Like these other folks said, check the manuals first and foremost. On the 90+ furnaces, most of them are able to be vented with PVC pipe. BE SURE to check the lengths of pipe the manufacturer says you can run, including any 90's and 45's. Most of the recommended lengths are a combo of supply air and exhaust. If you are running them from a first floor to a third floor roof, the lengths are going to be very critical.
    I have never been lost, but I will admit to being confused for several weeks.-Daniel Boone-

    Just because a person wanders does not mean he is lost.

  5. #5
    Join Date
    Mar 2008
    Location
    albany, new york
    Posts
    20
    the old system uses double lined metal piping. I would use pvc. I have never run pvc strait up through the roof. Thats my question. the old set-up is allowing all furnaces to be vented through one big pipe. Can that be done with pvc.

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,090
    Most, if not all 90's can be vented through the roof.
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  7. #7
    Join Date
    Oct 2006
    Location
    Northwest NC
    Posts
    70
    That will depend on the manufacturer. I personally would not do that. Every brand I have used so far has required seperate vents for each unit
    I have never been lost, but I will admit to being confused for several weeks.-Daniel Boone-

    Just because a person wanders does not mean he is lost.

  8. #8
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,090
    He will have to run a seperate PVC pipe for each unit, but they all can be vented up through the roof.

    Did an apartment complex, with Rheems. Ran all of them through the roof. No problems.
    That was 9 or 10 years ago.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  9. #9
    Join Date
    Oct 2006
    Location
    Northwest NC
    Posts
    70
    Sorry for the confusion. I meant I would not run them all into 1 pipe. I have also ran as many as 4 through a roof at once
    I have never been lost, but I will admit to being confused for several weeks.-Daniel Boone-

    Just because a person wanders does not mean he is lost.

  10. #10
    Join Date
    Mar 2008
    Location
    albany, new york
    Posts
    20
    thanks

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