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Thread: Condensation Leaking From Furnace Overflow Tube

  1. #1
    DIY Junior Member rvnmedic6869's Avatar
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    Question Condensation Leaking From Furnace Overflow Tube

    Due to the very humid weather lately, the AC condensation tube is allowing water to come up from under the concrete floor slab in the basement. I don't understand the original setup (as in the photo), but the condensation goes through the PVC pipe down under the basement floor. Now I've got a large puddle of water on the floor as the ground must be saturated and is coming back up through the opening.

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    My question is this: can I remove part of the bottom of the vertical pipe going into the floor and insert a 90degree elbow and a straight piece with an elbow downward into a bucket? I would love to direct the pipe to the open floor corner but it's on the opposite end of the basement. I realize I'd have to empty the bucket periodically but it would be much better than the small pond on the floor.

    Thanks,
    Bob

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    In the Trades Gary Swart's Avatar
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    It appears to me that the set up you have is a DIY P trap and an attempt to vent the drain. Not sure what the capped off vertical pipe is for. I think your idea will work OK, but it would be better if the line went to a floor drain, but if you don't mind the periodically dumping the bucket, your problem will be taken care of. The vent, although rather primitive, should be OK since the drain is not connected to a sewer.

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    DIY Senior Member Chad Schloss's Avatar
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    you can get a condensate pump and run a tube up and over to the nearest drain.

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    DIY Junior Member rvnmedic6869's Avatar
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    Thanks guys. I just ordered a Little Giant pump (1/50 hp model), also a check valve and 100' of tubing. The pump was only $35 on Amazon with free shipping. Grainger's list price was $84. Will be directing the flow to the other end of the basement into the open floor corner. Thanks for some fast, great info.

    Bob

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    DIY Senior Member Hairyhosebib's Avatar
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    The open pipe at the outlet of the trap is common practice. There is a whole mathematical equation about trap design. Trap height and trap length depending on sizes and fan speeds. When I first started working at ASU a contractor just finished remodeling a library. They installed a new fan coil AC unit. It wasn't too long after that that everyday at 5 PM the unit would shut off and all the water(condensate) that the fan was allowing the cabinet to hold would pour out of it! The drain was back pitched, vented at the inlet side of the trap and the trap was not sized correctly. When I see a truck with a bumper sticker that reads "CONTRACTORS BUILD CONFIDENCE" I have to laugh! The one thing about this mathematical equation that is funny is that they claim the filter needs to be dirty to get the numbers right. Seems like a cart before the horse situation. All this was told to us many years ago by a American Filter REP.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    Dumping water into the ground underneath a slab is just plain wrong...dump it out and down a drain. A good candidate for that is the washing machine standpipe, if your WM is in the basement. Just dumping it outside might work, depending on where it is, but damp soil may not be the best idea.
    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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    DIY Junior Member rvnmedic6869's Avatar
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    Quote Originally Posted by jadnashua View Post
    Dumping water into the ground underneath a slab is just plain wrong...dump it out and down a drain. A good candidate for that is the washing machine standpipe, if your WM is in the basement. Just dumping it outside might work, depending on where it is, but damp soil may not be the best idea.
    Jim,

    Excellent idea but the WM is on the floor almost above where I'll put the pump. The first rise from the pump to the basement ceiling is 8'. I would then need to run a horizontal section of tube for about 6' and then up about 5' to the WM standpipe.

    When the pump specs indicate a head capability of say 15', can that be cumulative with rises and straight sections? We're not talking about a large volume of water to pump so the gpm aren't a factor. I think.

    And you're right: the setup is dumb. We bought the house three years ago so I wasn't around when this installation took place.

    Thanks,
    Bob

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    Retired Defense Industry Engineer jadnashua's Avatar
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    It's the cumulative total rise. The condensate doesn't need to be pumped from the floor, you could make a platform for it on the side of the furnace and thus cut the rise down to within specs.

    You can pump it outside, but keep in mind that you may find that not the best idea. You could make a small drywell and dump it into there, but adding water to the ground near a foundation just isn't great. But, it won't be a huge amount, and one big rainstorm is likely to equal more than a whole season of running it.
    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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