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Thread: Slow drain

  1. #1
    DIY Junior Member alexh's Avatar
    Join Date
    Jun 2009

    Default Slow drain


    I just installed a 64k 5600SXT. I live in a slab house and the most convenient drain is an AC condensation drain pipe just outside the house. It's 1.5" and it simply protrudes about 6" above the cement next to the house. A 3/4" PVC pipe exits the house and terminates just inside the 1.5" pipe. I cut back the 3/4" pipe to test the drain etc. The drain goes to the sewer.

    The problem is that the drain rate on this pipe is less than 2 gal per min. Of course a high drain rate is not needed for AC condensation but it stills seems awfully slow. That pipe is not really exposed to a lot of debris but it has not seen much if any use in 15 years so it may need cleaning. Is it surprising that a 1.5" pipe would have a drain rate this slow or is this expected for a AC condensation drain?

    My only other drain is the washing machine drain which is inside the house. I would have to run the drain pipe into the house and the piping would be visible along one short wall of the washroom.
    My 5600 valve says 2.5ga/min drain on it but I think it's actually higher because I upgraded the tank from 40k to 64k and they sent me a new drain restrictor.


  2. #2
    DIY Senior Member mialynette2003's Avatar
    Join Date
    Nov 2010
    Ocala, Florida


    It is not recommended to run the drain in the condensation line because of possible damage if it backs up. I would suggest you run it to the washer drain in 5/8 tubing.

  3. #3
    DIYer, not in the trades LLigetfa's Avatar
    Join Date
    Feb 2011
    NW Ontario, Canada


    Before re-routing the drain, I would try snaking and flushing the existing 1.5" pipe with high pressure providing the 3/4" pipe can temporarily be removed to do so.

    I'm guessing that you are not tapping into the condensate line, that you are running parallel to it. Remember that you need to have a proper air gap.

  4. #4
    Water systems designer, R&D ditttohead's Avatar
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    Jan 2012
    Blog Entries


    The 1-1/2" condensate drains tend to get a lot of bio fouling in them. Condensate is usually almost purified water, no chlorine, no oxidizing agents. We have opened many AC drains to find the thickest, nastiest bio slime build up. looks like an elephant sneezed in your pipe. Ice maker drains do this a lot too. You should be able to clean it easily.

    The 2 cu. ft. system should have a 3.5 GPM DLFC button assuming your water temperature is normal.

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