Installing Utility Sink In Laundry Room - Main Floor

pieman312

I am trying to install a utility sink in my laundry room.
The home is a single story ranch on a slab - no crawl.
I am wanting to tap into the washing machine drain.
Should I tap into vent past the trap or should i connect
the drain directly into the 2" pipe directly from the washer drain?
I have been able to locate both pipes so just concerned as to
which one would be correct for connecting into or if neither should
be used.

USP45

The safest thing to do would be connect it into the vent ABOVE the washer. If its below then when the washer runs out the pipe may get filled with water causing negitive pressure (Vaccume) as it passes the sink drain. This will cause the air to want to come in from the sink drain through the sinks trap. this would suck the water out the trap allowing sewer gas to enter through to the house.

jpplumber

I don't know how high you want him to place this sink to get gravity drainage. Tie it into the washer drain but make sure you vent the sink at least 6" above the flood level rim of the sink and tie the vent into the washer vent.

pieman312

Thanks to both for responding
I was planning on putting a trap in the sink drain before tapping into either pipe. By doing this, could i then tap directly into the vent pipe and keep any sewer gas out....this would then eliminate need for venting the sink drain?

jpplumber

No, if you don't vent the sink drain the trap will have the water sucked out when you run the washer....vent the sink and keep the vent on the washer separate. You can tie both vents together at least 6" above the flood level rim of the sink and keep it above the washer box.

Marlin

I don't think you can wet vent a washing machine with a utility sink on a 2" line either. Do you have a picture of what you have?

ranman469

redo oops

ranman469

as defined in the upc you you can.
the washer on the botom. 2" then continue the 2" up the the laundry sink tee. this portion is the wet vent. sizeing is my min drain required. and up size 1 size . required 1 1/2 witch makes the wet went 2"

section of the upc 908.1 and 908.2 and table 7-3

pieman312

here is a picture of what i am looking at

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jpplumber

Good suggestion from Marlin and nice picture...or drawing, because I don't know what I pictured before but it wasn't that even though what I said still stands I will add to it.. You do not want to tie into the 2" standpipe...(plumbing code aside) not that it wouldn't work but every time you ran the sink you will hear the sound of water pouring into the trap...and again not that it wouldn't work but the vent should be 2" also if you want to tie a sink drain into it with a 1 1/2" arm to the sink trap. There is a certain distance (can't remember off the top of my head and don't have code book handy) that you can run the 1 1/2 arm to the trap without a vent.....the section between the the two sanitary tees on the vent will then be wet vented but it will beat breaking into the slab. I would also put a clean out into the vent in addition to the tee for the sink drain.

ranman469

i think i mis understood? you can not tie into the stand pipe. inlet side.
you can re size the vent then install another tee. the dist the trap arm can be is
3'-6"

pieman312

so that i am following everyone:
as long as the vent pipe is 2", i can come up at least 6" from the 'original T' and install another T for the sink trap arm?

Marlin

I edited your picture to show what I think is the best way to tie this in. The red section may or may not be necessary depending on how far from the stack the sink will be. I've always used 24" as a rule but have never actually seen the code.
The second fitting I added on the stack is called a tee-wye, anything below that second tee-wye needs to be 2" or larger. Anything above it is should still be ok with 1-1/2. Your local code will dictate if you are allowed to use that red tee why I have on it's side right after the trap. If you can't use it simply replace it with a wye and a 45.
The red pipe should be 1 1/2
As for the height to tie that red line into use 48" as my rule and it doesn't hurt anything to be too high. You need to be 6" above the sink or higher why tieing in that red line as a minimum.

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pieman312

Thanks to everyone

the sink will be right in front of the stack- talking less than 2 feet

everything else is understood now