Washing Machine DWV Question

Iminaquagmire · Feb 24, 2009

I'm in the process of installing a HE Maytag front load washer and dryer. I decided to change out the old gate valve supplies for a single handle ball valve one and change the 1 1/2" standpipe for the required 2". The valve is easy but I'm confused on how to properly reconfigure the DWV for the washer, which is currently wet vented over the kitchen sink drain which comes down from the second floor. I think I have it right but just want to make sure.

The plan is to take the santees for each fixture and replace them with a double fixture fitting, and also putting another cleanout below that. Sound acceptable?

NHmaster · Feb 24, 2009

Leave the kitchen sink drain where it is and change that to a 2 x 1 1/2" san tee. A cross would be a bad choice because the washer would blow back up into the sink side.

Sponsor · 2022-01-29T12:20:58-0800

Iminaquagmire · Feb 24, 2009

I wasn't proposing a double santee, I was going to put in a double fixture fitting like on a double lav. Would that have made a difference?

Anyway, I thought about the force of the water from the washing machine (reason for the 2" standpipe) and ended up putting the sink drain above the washing machine drain. I also put a cleanout above the sink drain and below the washing machine drain. I know ideally they would be on separate lines to the stack and separately vented, but this was the best solution I thought.

Was I wrong?

Terry · Feb 24, 2009

You can't dump the upstairs kitchen waste over the santee for the washer. That will suck the trap dry on the washer.

Are any of those pipes a vent?

You do need to vent the washer trap and arm, above any waste they may connect to the stack.

Terry · Feb 24, 2009

Here you will notice a separate vent for the washer.

Iminaquagmire · Feb 24, 2009

The top 1 1/2" line is a vent. It has nothing above it. Judging by the picture, if I cut in a wye for the washer trap arm and tie it in at the vent arm, I'll be fine then? Red line shows wye cut in to washer trap arm, with the outlet tying into vent run to roof.

Terry · Feb 24, 2009

If you cut in the wye fitting for the vent, yes.
Just make sure you flip it the other way. The wye should be pointing downstream.

hj · Feb 25, 2009

drain

You changed a correct installation into a bad one. Your washer was NOT wet venting anything, nor was it wet vented, and it had a proper vent. All you would have had to do was change the washer connection to 2". NOW you have wet vented the washer with the upstairs sink and that is NEVER permitted. Another case of a little knowledge being a dangerous thing.

Iminaquagmire · Feb 25, 2009

It was never proper to begin with. You're right that the washer was never wet vented, but it did drain OVER the kitchen sink which to my understanding, would have been wet vented and is much worse than the way it is now. If I put the vent in the washer arm, it'll be exactly like Terry's picture.

Terry · Feb 25, 2009

The first picture here, shows a vented washer, with the upstairs kitchen coming in below. This is the preferred way to plumb this.
The only thing lacking was pipe size, the washer and the kitchen sink should be run in 2"
If you can duplicated this, with 2" pipes, it would have been perfect.
The vent can stay 1-1/2"

The kitchen below the santee for the washer is not a "wet vent"
The vent is on the top of the santee for the washer.
Since no water is in the vent, the vent is dry.

When you drain a fixture into a vent, then the vent becomes wet.
But you can't wet vent a kitchen over a washer
And you can't wet vent any upstairs fixtures to lower the fixtures.

Iminaquagmire · Feb 25, 2009

OK. I was made to understand in this thread that the washer should never be vented over a kitchen sink because it dumps too much water.

Assuming I put in the wye for the vent on the washer trap arm, I'll be OK right? Or is there a better way (short of a separate drain for each)?

hj · Feb 26, 2009

drain

quote; it did drain OVER the kitchen sink which to my understanding, would have been wet vented and is much worse than the way it is now.

You have completely misunderstood the wording of the plumbing code, and/or whoever told you that. As I quoted, "A little Learning is a dang'rous Thing; Drink deep, or taste not the Pierian Spring". The sink is independently vented so the washer is NOT wet venting it. The only way it could wet vent the sink in that configuration would be if the sink were next to the washer and it was using an illegal "S" trap, neither of which is the case.

Iminaquagmire · Feb 26, 2009

You're absolutely right. I glossed over the fact that the sink would have its own vent upstairs. If it was wrong, i wouldn't have left it like that and I didn't. That's why I asked here--I was unsure. That's hardly dangerous. Anyway, I cut in a new vent for the washing machine and finished putting everything together last night. I appreciate the help. Another project done.

hj · Feb 27, 2009

correction

Without seeing what you did, we have to assume you did it correctly, HOWEVER, if you had asked first and then followed our instructions, you would not have converted a faily simple task into a major repiping project.

Themp · Feb 28, 2009

The picture that was posted by Terry(to show a washer vent)with the yellow insulation and ABS pipe looks really professional but what is the black hot/cold supply lines running to the washer connections? It looks like it is insulated copper pipe but looks flexible as it curves. Why the change in pipe here?

Tom

Terry · Feb 28, 2009

PEX piping with foam insulatation.
The insulation was installed to prevent sun from hitting it during construction.

Most of that house was done in PEX, except for the stub outs and to the valves. Just a preference. It could have been all PEX too.
Or all copper.

hj · Feb 28, 2009

pipes

It could have been insulated copper, but here, inspectors would have a problem if plumbers used soft copper above the floor, and bent it like that.

Terry · Feb 28, 2009

inspectors would have a problem if plumbers used soft copper above the floor, and bent it like that.

They don't let me use soft copper above ground like that in Seattle either. Go figure. If it's in the ground I can bend it.

Above ground, they like straight pipe and fittings.

But with PEX, heck, you can't keep it straight anyway.

Washing Machine DWV Question

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