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Thread: Condensate pump drain

  1. #1

    Default Condensate pump drain

    My gas furnace and humidifier currently drain via 3/4" pvc into a rinkydink condensate pump that pushes the water to a laundry sink via a 3/8" flexible, plastic tube. The laundry sink drains to a sewage ejector pit, which pumps to septic.

    Instead of "double pumping" the condensate, I'd like to drain directly into the sewage basin. The questions are this:

    1-Is this permissible? Pretty sure it's ok bkz it's a low volume of water, but just checking.

    2-Since the drain will now discharge via a sealed line to the basin, am I required to vent the 3/4" drain from the furnace? The volume of water is so small, I doubt it'll ever self-siphon. The basin is already vented.

    Any help appreciated

  2. #2
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    New Hampshire


    "What works safely" and "what is code" may not be the same.

    Do you have enough elevation on the condensate drain to run it into a nearby toilet, or a toilet tank, or drain it into a shower?

    If none of the above are available, and your drains are above the top of your sewage basin, you could put a tee or tap a small elbow fitting into the side of the vent from the sewage basin, and connect the condensate drains into a P-trap constructed with fittings large enough to handle the condensate flow. The risk of that is that if the sewage basin floods above the top of the connection, it will back up into your condensate drains.

    I suppose you could also put a trapped connection into the top of the sewage basin and connect a vent from it into the vent of the sewage basin, at least 6" above the highest fixture that drains into the basin.
    Last edited by Bob NH; 03-13-2006 at 07:11 AM.

  3. #3

    Default Thanks

    The furnace drain already has a trap. I'll just drain it through the basin's vent stack like you suggest. If there's a problem down the line, it'll be simple to reinstall the condensate pump anyway and drain through the laundry sink.

    Thanks, Bob.


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