Draining utility sink in laundry room

[Ssm623]

Apologies if this has been asked before, but I can’t find a specific question like mine.

I have a laundry room with a large crawl space beneath it. The washer drains into a 1.5” ABS pipe, and the p trap and vent are behind drywall. The 1.5” runs to the main drain (4” I think). My plan for draining the utility sink is to tee into the ABS a few feet below the floor and 6 feet downstream of the washer. The sink will have a p-trap with an AAV, which I did read is up to code in my area. The AAV will be 4” above the p trap.

My question is, is this an acceptable design or do I risk flooding from the washer?

 

[Breplum]

Washing machines by code should be on a 2" line, and would be fine sharing a drain.
In your case, you should be ok, but....don't use a tee, use a drainage fitting, like a wye if the pipe you are connecting to is horizontal.

 

[Sponsor]

 

[Jeff H Young]

Personally have never run a Washing machine drain in 1 1/2" pipe and I dont run a kitchen sink or laundry/utility sink on less that 2 inch (excluding the trap arm and trap)
Depending on the dificulty Id like to gut out all the 1 1/2" or if you dont want drywall repair or open wall to do it right the least you could do is cut a new wye or combi into the 4 inch main and run 2 inch to your new sink up to the santee under sink .
If you choose to use an aav on a undersize line branching off a wash machine expect gurgling at utility sink . you might be luckey almost anything will kinda work and drain