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  1. #1
    Join Date
    Nov 2009
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    Incline of Exhaust or Flue Pipe question

    I had a high efficiency gas furnace installed early summer by an out of work former HVAC installer. This winter, I turned on the heat and it worked fine for a few days. Called up the installer and his number is no longer operational. Went to his house and he's left for parts unknown presumably for a job.

    Anyway, the heating system shut down after a few days. Come to find out that the flue/exhaust pipe near the furnace was full of water. Well I drained it, made sure that the end exiting the house was turned down so water wouldn't get in and, the system worked, for a few days. Again, the water problem.

    It seems to me, that the steam in the exhaust gases is condensing on the cool PVC and backing down to the furnace exhaust port. Is the exhaust/flue pipe supposed to have a slight upward incline in these new systems like mine does. If not, where does the water that condenses in the flue pipe go??? I know there is a drain but, I figured that was for the AC.

    Dave in NC

  2. #2
    Join Date
    Apr 2004
    Muskegon, Mi.
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    Check the installation manual that came with the furnace. That info will be in there. Like the saying goes "You get what you pay for."

  3. #3
    Join Date
    Aug 2009
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    The exhaust should have a pitch downward toward the furnace to allow the water into the furnace. Their should be a drain hose hooked up to the inducer fan inside the furnace that drains out with the A/C drain. Make sure that their is a trap in the hose. If this is not how the system is I would call someone to fix it. Like Woodsman said, "You get what you pay for".

  4. #4
    Join Date
    Dec 2009
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    Its usually 1/4 inch per foot .sloped back towards furnace and a support bracket every 6 feet to eliminate sags and the exact problem you seem to be describing.would agree though about install manual all specs should be very clear there... good luck...

  5. #5
    Join Date
    Feb 2004
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    Bite the bullet and call a pro out to look at the install. The flue issue is probably merely one problem of several.

    The downsides to a bad install by a non-professional come in the form of:

    Hazards to your health
    Hazards to your property $$$$
    Higher energy bills $$$$
    More repairs $$$$
    Shorter system longevity $$$$
    Clouded warranty status $$$$
    Busted by mechanical inspector & have to shell out $$$$ when you go to sell the house.

    I see these all the time, and the costs of the downsides typically drastically outweigh the money saved by not calling a professional company to do the install.

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