Help with adding drain line for washer outlet box

[cmwand]

I'm aiming to add a washer outlet box drain line to a wall that currently has a sink drain line, vent, and drain line from the floor above and would like to get some advice on the best way to re-do the drain/vent lines. I've attached a photo showing the existing situation. These are all 2" ABS pipes.

From left to right in the photo, there is the sink drain line stubout (p-trap has been removed). The sink drain line connects to a vertical stack that goes upward to serve as the vent for the sink drain. Below where the sink drain connects to the vertical stack, is a wye that branches off to the right. The pipe coming down on the right that connects to the wye is the drain line from the floor above (this is a ground floor unit in a multi-unit building). Note that the left stack has a sanitee above the sink drain sanitee; ignore that upper sanitee because that was for a sink drain on the opposite side of the wall (the drain stubout is partially hidden by the metal stud to the right of the left stack) and is going to be removed and the vertical stack restored in its place).

I'd like to add the washer outlet box with drain in between the two vertical stacks (the sink vent being the left stack and the drain line from the floor above being the right stack). I've gotten conflicting opinions on the proper way to do it so any expert advice would be appreciated. I know I'll have to move the right stack over a little bit further to the right to make room for the washer outlet box. So one of my questions is whether it's more appropriate to continue the 45 degree drain line up and to the right and move the right stack over further or whether I could combine the sink drain and where the right stack meet the left stack into a single fitting like a double fixture tee/double combination wye.

My other question is when I add the washer outlet box drain into the left stack, do I need to re-vent the sink drain line back to above where the washer drain line comes into the left stack (indicated by the dashed line in the drawings of Option 1/Option 2)? I've attached a sketch showing the original plumbing setup as well as what I'm currently contemplating as two options (I'm open to other options too, these are just the two that I've been able to come up with based on consulting with some folks and reading up as best I can).

Thanks in advance for any advice!

- Chris

P.S. I also do know about the requirement for an 18" vertical "stack" above the washer drain p-trap to contain any sudsing, but are there other peculiarities, either code or just good plumbing sense, when putting in a washer drain?

 

[Terry]

Option one looks better.

 

[Sponsor]

 

[cmwand]

Option one looks better.

Thanks for the quick reply Terry. Am I correct in my belief that I'll need to add a new vent connecting the sink drain line to the vent stack on the left above the point where the washer drain ties in?

Also I'm a little concerned that maintaining the 45 on the right drain line (especially since I need to move that right drain stack over further to the right meaning the 45 section of drain will continue up even higher) might not give me enough room for a tall enough washer drain standpipe. Would it be really bad to use option #2? Or as option #3, could I use long turns or 45 elbows to have the bottom part of the right drain stack tie in horizontally to the left drain (thru a wye and a 45) rather than the 45 degree line that pitches up and to the right?

 

[hj]

1. You already have two tees in that line. Is one of them going to be eliminated? If not your washer tee may be too high and BOTH will need revent connections since they cannot be wetvented with a washing machine drain line. There are ways to accommodate the new P trap without changing the upstairs sink's connection into the vertical stack.

 

[cmwand]

HJ you're right, there are two tees. The upper tee is going to be removed and that's where I would tie in the tee for the washer drain line. I'm still concerned that keeping the right drain stack arranged so it ties in on the 45 might make it tight to put the washer drain ptrap in between the two stacks. Any thoughts how bad it would be to have the right drain stack tie in on the horizontal using a long turn and a wye plus 45?

 

[cmwand]

I realized my question above in post #5 about moving/modifying the right drain stack was a bit hard to understand, so here's a sketch of what I'd like to do to be able to move the right stack even further to the right while keeping the part where it 45's back to the left drain/vent stack from encroaching on the space where I need to put the washer drain p-trap/standpipe. Hope this helps illustrate. I'd obviously try to keep the horizontal section in the right drain stack as short as possible (it probably wouldn't be more than 9" long) and would use 45's to smooth the flow into and out of the horizontal section.

 

[hj]

A 45 into a long sweep 1/4 bend would do the same thing.

 

[cmwand]

A 45 into a long sweep 1/4 bend would do the same thing.

Thanks HJ! I figured as much so it'll just come down to what parts I have available.

 

[hj]

quote; it'll just come down to what parts I have available

That is how most DIYers do their jobs, and why they often do it wrong and have problems afterwards.