A question on adding a utility sink in a Washing machine

[Mattincibolo]

A question for the experts. Currently i have a washer/dryer on the second floor of my house to service the 4 bedrooms upstairs (there is a laundry room on the first floor for the downstairs bedroom, kitchen, and pool).

The drain line is 2" (by code), and the vent line is 1 1/2" which goes into the attic and outside to vent (not shown in the attached drawing).

The drain line (in black) goes down into the garage below (on the first floor) where it curves as shown and into an existing drain line behind the wall and out to the city sewer.

The questions: (1) Can a utility sink be added in the short run between the drain stack (where it comes down from the second floor) and goes into the wall? (The line is in red)

(2) what fixture would be used? A 1 1/2" sanitary tee (into a 2"pipe) or a 1 1/2" wye?

(3) would a 'wet vent' be required for this utility sink (as indicated by the red dash)? A separate vent to the outside is not possible. There would be nothing but the discharge from the washer above. There is no other device draining into this line, i can't imagine the washer discharge causing the pee-trap on a utility sink to be siphoned out...could it?

 

[Terry]

The drain from a washer upstairs is never a vent for the downstairs. The sink below will need to be vented.

Any waste line connecting to a horizontal drops into a wye or combo fitting.
A waste line connection to a vertical line can be a santee, wye or combo.

When adding a vent, on the vertical it's a santee, the horzontal, a wye or combo.

 

[Sponsor]

 

[Mattincibolo]

Thank you for the quick response! I am surprised a 'wet vent' would not work in this situation. Guess i will forgo a utility sink in this location because our code does not allow for a passive air emitter in lieu of direct vent and given the location of the garage, a direct vent us not possible.

There used to be a utility sink in the garage (when i bought the house 5 years ago), but it was on a different wall and drained into a 1 1/2" drain line shared with a shower on the opposing internal wall (and wasn't even wet vented). Wondering why that was allowed? Because of it being a shower drain line? Or has code changed over time where all fixtures need separate venting?

 

[Terry]

Wet venting is for bathroom fixtures only and then only on the same floor.

A washer has never been included for wet venting. It's a pumped fixture. In some codes the 2" p-trap dumps into a 3" waste line.

 

[Mattincibolo]

Hence why i asked the experts in here! THANK YOU!

so, could the utility sink go back where it was (different wall, was shared with bathroom shower in same floor)?

at the end of the day if it can't be done (short of separate vent, and the previous owner had put a sink there and didn't pull a permit or had it inspected) it's no big deal as i can't imagine i'd ever use it much (previous owner often did car repairs in his garage).

 

[Terry]

A utility sink is not part of the bathroom group. Often they are used with washing machines. And hand sink for washing up is part of the group though.
What I see with a utility sink, is a pretty small drain though. Was the sink that was installed before using the shower 1.5" vent for a drain?
For code they normally want the wet portion to be 2" but might be different in Texas.
I think I would go with putting the sink where it was, or if you add a sink to the washer waste, have an AAV between the trap and the stack. We do them on kitchen sink drains all the time.

Auto Air Vent

 

[Mattincibolo]

It actually is a pretty small drain when you think about it and it does remind me a lot of a bathroom sink, the only difference is is it was in the garage and it was actually very deep. the previous owner runs a car repair shop and sometimes he did repairs at home which is why I think the sink was there to begin with but I know I removed it because I had to do some other things around the garage and it was in the way. I never put it back in its current place and I just capped off the drain it was using. maybe it was inspected once upon a time and it was considered a hand-washing sink and not a utility sink.

like I said, at the end of the day if it's just too much of a hassle and could cause inspection concerns, it's just as easy for me to sell the sink to someone else who can use it.

and I do thank you for the very quick and thorough replies because I certainly wasn't expecting that. I much greatly appreciate it!