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  1. #1
    Join Date
    Dec 2007
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    Gurgling in new furnace exhaust pipe

    Hi, I just read through a couple of other threads and I didn't see a definitive answer, so let me try my own thread.

    Thank you in advance for your help!

    New furnace installed in my attic by a licensed local HVAC contractor. Young guys, let's face it, probably don't REALLY know what they're doing...especially based on me having to help rig up the electrical supply for it.


    Notice water splashing out of the outdoor vent PVC. 2" PVC that exits to the outside of the house, into an upturned 90 with a screen or whatever to prevent anything from crawling in.

    The exhaust line looks perfectly level with a slight sag. It sounds like there's just water trapped at the upturned 90 and it's gurgling when the furnace runs.

    This seems like the problem is that the exhaust line doesn't slope up enough, so the water is collecting. My question more is, when it's properly sloped, does the condensation just drain back into the furnace and exit through the smaller PVC pipes that exit to the outside?

    Is the solution for them to properly slope it?


  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
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    Gurgling means the pipe or fittings are trapping water. Must not be enough to shut you down but should have a rise from outside to the furnace so all water drains out through the furnace.

  3. Likes JeffWil liked this post.
  4. #3
    Join Date
    Jul 2007
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    Do you have a short run of combustion air and vent pipe? How long are they (furnace to outdoors and how many 90 and 45's).

    What is the model number of this unit?
    Instead of learning the tricks of the trade, learn the trade.

  5. #4
    Join Date
    Dec 2007
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    Venting, the pipes for intake and exhaust, should be sloped at 1/4" per foot back towards the furnace to allow water/condensation to drain. It could, if allowed by mrf, slope towards the exit of the pipes as long as the water/condensation can drain. in your case, it can't

    Pipes sound like they are incorrectly installed.

    I would NOT put a screen on the exhaust pipe if there is any chance of below freezing temps. This could freeze over and keep the furnace from running.
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