Need advice on standpipe for stacking washer and ventless dryer

Old 04-05-17, 01:42 PM
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Need advice on standpipe for stacking washer and ventless dryer


I am trying to figure out how I would go about installing a stacking washer and dryer in a closet. The dryer would be a ventless dryer (which requires a drain) because I have no dryer vent and installing one would require going through 2 walls.

There is already a supply box for the washer (supply hoses and properly trapped and vented drain). I don't think the washer and dryer can share the drain in the box though (it is a tight fit and 1.5inch in diameter). However, whoever remodeled the house before installed a 2 inch ABS drain pipe sticking out of the wall horizontally (no trap, but I believe it shares venting with the washer drain).

I managed to get a 45 degree elbow and a vertical piece of ABS pipe installed to that. Pic here: Imgur: The most awesome images on the Internet

I know that it now needs a trap, but before I go any further I wanted to ask about feasibility.

My next idea is to install another 45 degree elbow, a horizontal piece of ABS pipe for a "trap arm" (since it is 2in pipe this has to be at least 4 inches long?), a P trap, and then a vertical pipe on that for the dryer to drain into. A rough sketch (please excuse my paint skills): Imgur: The most awesome images on the Internet

Since the dryer would be sitting on top of the washer the whole thing needs to be a total of 70 inches or taller (Washer height plus minimum standpipe height of 30 inches).

Will this work at all or should I give up?

Old 04-05-17, 04:23 PM
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I'm not a professional plumber. I am not familiar with the pipe coming low out of the wall. I can't imagine why that pipe would be stubbed out there except for use as a clean out.
I would recommend you contact a city inspector. Personally I haven't seen a condensing dryer.
Since the dryer looks to be draining condensate only, the inspector might let you tie into the existing drain or a nearby lavatory sink using a branch tailpiece.

In California I have seen many air conditioning units tied into lavatory drains using 7/8" ID hose.
The condensate drain is hard piped into the bathroom and the hose goes from the wall to the branch tailpiece.
Old 04-05-17, 05:45 PM
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If the washing machine box is 36" or so off the floor it is fine. Why do you think it needs to be extended 30"? The washer height is the same as it would be without stacking. Only the dryer is higher. Are you planning on using the already installed washer box drain for the washer? How big is the drain on the dryer?
Old 04-06-17, 09:46 AM
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Whatever that pipe is at the floor level is most likely NOT where you should be draining your washer. Even if it was set up like that, it's definitely wrong.

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