Plumbing project and venting

benleef

Hi all. I live in a home built in 1928. I've been having issues with my washing machine backing up at the stack drain pipe and spilling water on my basement floor.

I was planning to remove a section of galvanized piping in the basement and replacing it with PVC. My suspicion is that the trap for the washer drain is clogged and that the pipe is sized too small. Part the the section I plan to remove and replace is the drain for the kitchen sink which is almost directly above the washer (or 4 feet to the left of the washer drain stack pipe). I may also add a laundry sink next to the washer.

While investigating, I've noticed that there is no venting of the sink in the kitchen. There is also no venting of the laundry drain, but it is very close to the main vent stack as you can see from the pictures. The galvanized pipe running straight up goes to the ceiling, takes a 90 degree turn and heads about 4 feet where it again takes a 90 degree turn up through the ceiling to the kitchen sink.

Is this a problem that there is no venting in the kitchen sink? It seems to work fine. Is it a problem that the laundry drain has no vent if it is so close to the main vent? Any advice on how to tackle these issues?

Thanks!

Attached Thumbnails

   

Alan

So the 2" wye in your picture is not a vent, but rather the drain for the kitchen sink?

__________________
Journeyman Plumber

benleef

Yes, it runs up to the ceiling in the basement, takes a left turn, runs a few feet, then turns up into the floor of the kitchen under the sink.

Alan

So your kitchen sink drain isn't in the wall then, is that correct?

__________________
Journeyman Plumber

benleef

Correct, the sink drain runs through the floor and not into the wall

benleef

Should I install a sanitary T in the kitchen sink cabinet with a AAV? Then do I need an vent for the washer drain stack? or is it's proximity to the main stack sufficient?

benleef

If this helps, the diagram below is how I'm thinking of proceeding---will this work?

Attached Files

drawing.pdf (87.9 KB, 39 views)

Alan

That's what I would do.... replace it all the way down to the cast iron hub with a fernco donut.


I'd also vent the washing machine with it's own AAV as well. More airflow is always better.

__________________
Journeyman Plumber

benleef

Thanks, is my drawing correct? Do I put the AAV between the fixtures and the main stack? Can sink and washer share drain pipe like in the picture? Would do 2" drain pipe

Alan

The sink and washer need to vent separately off of the drain, and they can share an AAV after they tie together.

__________________
Journeyman Plumber

benleef

Thanks for your help, but I don't understand that they need to vent separately but can share an AAV?

Alan

It has to do with the distance from the trap to the vent, and the amount of slope on the pipe....

the second trap can cause the first to siphon out if it doesn't have airflow to that section of pipe, and vice versa for the other trap.

__________________
Journeyman Plumber