[stephenm]

Hello,

Thanks for taking the time to help.

I am installing a stackable W/D in a pantry adjacent to my kitchen. I am planning to install a washer box with 30" standpipe (2" diameter) with P-trap. I will then elbow the 2" washer drain to slope at (1/4" per linear foot) towards the kitchen. When we reach the kitchen, our drainpipe will be directly below a double sink.

The existing double sink is trapped and enters the 3" vertical main drain behind installed cabinets. It will be difficult to remove everything to see the main drain.

My hope is that I can do the following:

I want to join the washer drain to the kitchen drain after the kitchen trap. So both drains will have their own traps, but will connect in 2" PVC before elbowing into the 3" main drain.

I also can install a AAV for the washer drain in the middle of the sloping PVC pipe, if it is necessary.

Thank you so much for your help! I can't wait to get started!

[massplumber2008]

Hi Stephen...

By connecting into the kitchen sink drain just after the kitchen sink PTRAP you will be discharging a major fixture past an unvented PTRAP which could potentially siphon the trap of its water and allow sewer gasses to enter into your kitchen... *UGH*... so I can't recommend that you go this route, OK?

Here, although I understand your thinking/desire, the kitchen sink vent's contribution to the kitchen sink trap is negated as soon as you connect that washer drain between the kitchen sink vent and the kitchen sink PTRAP... really only an issue when the washer drains, but when the washer drains, as I mentioned, the trap can be siphoned dry... ;)

You will be better to connect under the connection to the kitchen sink drain, or another option may be to connect an AAV between the washer connection and the kitchen sink PTRAP, but I didn't recommend that, OK?

You will also definitley need an AAV at the washing machine drain pipe... piped as shown in the diagram below, OK?

More questions, just let us know, OK?

Mark

[stephenm]

Here are two angles of the sink-- for a better visual.

[stephenm]

That's very helpful. I can put an AAV at the washer machine drain pipe, no problem. Is there a recommended distance between the trap and the AAV?

Moving further down the pipe, I lose you a little bit on your advice. I am assuming you are ""not"" recommending to install another AAV post kitchen P-trap and then connect the washer drain pipe post AAV?

So it would go like such: Kitchen P Trap > Kitchen Drain > AAV > Washer Connection > Continue Kitchen Drain to Main Drain.

I'm new to this all- but I'm anxious to learn and I'm very cautious. Thanks for your help.

[massplumber2008]

If AAVS are allowed in your area then you can try piping this up as drawn below (see image). It's a tight fit under the sink so it won't look exactly as I have drawn, but you should get a pretty good idea of what I am shooting for.

The WYE fitting for the washer can go left or right... ;) The distance between the washing machine trap and the AAV cannot exceed 5 feet.

Back to you...

Mark

[stephenm]

Thanks so much. This is really great info. I never thought I would have had to put two AAV's in-- but it makes sense now. I think "tight" is an understatement for the amount of plumbing that's going to need to be under the sink.

The 2" wye that will extend from the elbow that is coming out of the wall is going to interfere with the existing kitchen drain. I suppose that the best (only) way to handle this is to revamp the kitchen drain.

Also, since the wye fitting will be fairly high- and we have to account for 3" for slope- the washer box is going to have to be higher than I anticipated. Anyone know off-hand at what height when washer drain hoses can't reach the box?

[massplumber2008]

Each washer is different, but with what I see under your sink , if you hang the washing machine box just above the washing machine you should be all set.

In my area code requires the standpipe out of the PTRAp to be between 18-30" so anywhere in that range will be just fine!

Mark