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Thread: Backup from main line through condensate drain

  1. #1

    Default Backup from main line through condensate drain

    We recently had a new heat and air unit installed. Now we've got a main line backup that has flooded through the condensate drain pipe back into the unit.

    I've attached a couple of pictures showing the drain pipe. The first picture shows the pipe coming out of the unit. From there it proceeds level, with a couple of turns, until the second picture, which shows it connecting with the drain pipe from the washer and dryer, I think.

    I don't know anything about plumbing codes and was wondering what folks thought about this setup. It seems to me crazy to leave open the opportunity for water to flow straight back into the heat & air unit like that.

    Thanks,
    Lee
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  2. #2
    Senior Robin Hood Guy Ian Gills's Avatar
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    I am not a plumber and I am not licensed to do any HVAC work and charge for it but it is clear that a condensate line cannot go straight into a sewer or drain line for the very reason you have explained.

    Any sewage backup would spill directly into the unit not to mention sewer gas entering the house. I bet when you did some washing with the AC on you could smell sewer gas in the house, coming through the registers no?

    A condensate pipe should have a one inch air gap above a floor drain and cannot directly enter a waste line like that.

    Or you can use a condensate pump like I do to pump the condensate outside. Where pumps are used, they should be installed with a factory equipped auxiliary high level switch that shuts off equipment served upon activation of the auxiliary high level switch. Where damage to any building components will occur as a result of over flow from the pump, the pump shall also be located in an auxiliary drain pan or in a separate drain pan equipped with a separate drain line or water level detection device. Condensate shall not discharge into a street, alley or other areas so as to cause a nuisance.


    If you tell me a registered HVAC specialist installed that, I will never hire another licensed professional ever again in this country to work on my house.

    The pipe clearly looks older than the AC unit, so someone may have been lazy. Some of the laziest people I have ever met are Amercian licensed plumbers and electricians.
    Last edited by Ian Gills; 09-03-2009 at 12:37 PM.

  3. #3

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    Thanks, Ian.

    I have a couple of followup questions. Given that quite a lot of water flowed back into the unit (it was spilling out of the unit and causing part of it to sag), should I assume it needs to be replaced or is it possible it can be vacuumed and dried out?

    In the first picture, what is the purpose of the U-shaped bend that the pipe takes? Would that prevent sewer gas from getting into the unit? So far we have not had any problems with sewer gas.

    Finally, can I assume the company who did the original install is liable for the cost of repairs, assuming the setup does violate code? (FYI, the OKC Muni code just references the Int'l Plumbing Code, a copy of which I have not tracked down yet.) If nothing else, this question should make it clear I am a total newb at all of this . . .

    The HVAC company is sending someone over this afternoon, so I will get their take on it shortly, but am hoping to arm myself with a little better information before then.

    Thanks all,
    Lee

  4. #4
    Senior Robin Hood Guy Ian Gills's Avatar
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    We need a pro to come along and answer those questions. Like I say I am just a DIYer and Terry would argue a bad one at that.

    My gut feeling is the unit will need to be replaced because the warranty must have been made void.

    The U-shaped bend looks like a half-arsed attempt at making a trap that I doubt would have been effective because it would have probably dried out and may not be properly vented. But that is a minor point because the condensate line should not have been terminated directly in the sewer line any way.

    I do not know about liability. The funny thing I have never understood about America is the homeowner is utlimately responsible for getting permits and inspections done. Absolutely crazy. It makes you wonder what we pay licensed professionals for.
    Last edited by Ian Gills; 09-03-2009 at 01:51 PM.

  5. #5
    Retired Defense Industry Engineer jadnashua's Avatar
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    It depends on what got wet. A gas valve that gets immersed must not be reused - it needs to be replaced. Electronics, probably would fail soon, too, if wetted.

    As mentioned, you need an air gap. The fabricated trap would probably work, and if it was indirectly draining, there'd be a real trap and vent to keep sewer gasses out of the unit.

    Gravity is always nicer than having to use a pump, but often that's not a possibility. Draining condensate from a furnace outside can be a problem: it can often freeze, and second, it is often acidic and would kill anything nearby, poisoning the soil.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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