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  1. #1
    Join Date
    Oct 2003
    Posts
    2,866
    I was following up on an inspection report about a cracked heat exchanger in a goodman gas furnace(horizontal in a crawl space). Yes 1 of the cells has a long crack easy to see. My question is about the 5 in single wall stack pipe. It leaves the furnace goes 10 ft horiz. goes thru the brick and block foundation then turns upward with a 90, enters 7 or 8 inch single wall pipe, rises 25 ft , goes thru the soffet then out the roof and exstends past the roof line apout 4 ft. Anyone else seen 1 this way? If i deside to use another 80 plus furnace can i use the same vent. Im going to ask an inpector to look at it with me but I just wanted your input. Thanks.

  2. #2
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,319
    Vent in a crawl space should be double wall. 7-8" single wall way too big for a furnace also.

  3. #3
    Join Date
    Jul 2000
    Location
    NW IL.
    Posts
    3,935

    Thumbs up

    Loonie's right vent is wrong and could be a contributing factor to heat exchanger's demise.
    Aircraft Mechanical Accessories Technician. The Air Force changed the job title to Air Craft Environmental Systems Technician. But I've decided I'll always be a Mech Acc.

  4. #4
    Join Date
    Sep 2001
    Location
    Vancouver Canada
    Posts
    996
    Must use "B" vent to vent exterior pipe, also must be contained in a shaft or chase and insulated or you are asking for big time condensation problems as well as possible back venting due to the furnace vents inability to overcome all that cold air contained in the vent pipe. The key to good venting practice is to keep the pipe warm in order to create a good draft. If piping is run through a lot of unconditioned space it will not vent correctly. This will certainly go a long way towards destroying your heat exchanger. A naturaly vented furnace is not a condensing furnace but it will sure act like one with a freezing cold vent.
    "Go big or Go Home"

  5. #5
    Join Date
    Mar 2005
    Location
    burlington county n.j.
    Posts
    9,754
    go 90% furnace and rip that crap out.

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