Users who are viewing this thread

John Bush

New Member
Messages
2
Reaction score
0
Points
1
Location
Spokane, WA
Right now, my washing machine in the basement drains into one of those very old, super-heavy concrete utility sinks. The sink is starting to crack and leaking more often, it often clogs with the lint from the washer, and we're tired of switching out the mesh sock covers. I want to put in a standpipe for the washing machine to drain into and avoid the sink altogether.

Attached is a sketch I drew up that shows my drainage and venting system. The solid lines are the pipes I can see and know; the dashed lines are what I can't see, but I'm making an educated guess at. In red pencil, I've sketched out what I'm thinking for the standpipe, but want feedback on if this will work and if it's vented properly and that I won't have to worry about backup or overflow.

To summarize it, I want to cut into the copper drainpipe that runs from the kitchen sink upstairs, put in a PVC (or ABS?) sanitary t, run it to a p-trap, and then the standpipe. Is there anything else I need to do or think of?

IMG_1147.JPG


THANK YOU!!
 

Terry

The Plumbing Wizard
Staff member
Messages
29,942
Reaction score
3,462
Points
113
Location
Bothell, Washington
Website
terrylove.com
The washer needs it's own venting. The vent from the washer can ti into the laundry sink vent at 42" above the floor.
Without the washer being vented, the upstairs kitchen sink will be siphoning the trap.

You can't run water from the sink down the washer vent.

dwv_b2.jpg


washer_rough_b.jpg
 
Last edited:

John Bush

New Member
Messages
2
Reaction score
0
Points
1
Location
Spokane, WA
The washer needs it's own venting. The vent from the washer can ti into the laundry sink vent at 42" above the floor.
Without the washer being vented, the upstairs kitchen sink will be siphoning the trap.

You can't run water from the sink down the washer vent.

dwv_b2.jpg


washer_rough_b.jpg

Thanks so much, Terry - this really helps. I saw this diagram before, but was trying to best interpret it for my setup. Based on this, I mocked up two options to properly vent it. The red pencil is what would be new piping. Would you recommend Option A (tie into kitchen drain stack) or Option B (tie into Utility sink drain stack) below? My gut says option B so that I only need to cut into one pipe and can just put ABS in there. Thanks again - this place is a welcome wealth of knowledge!
Option A (kitchen sink drain).JPG
option B (Utility sink drain).JPG
 

Reach4

Well-Known Member
Messages
39,268
Reaction score
4,535
Points
113
Location
IL
The vent split has to be at least 6 inchs above the rim of the sink and the top of the standpipe.

I suggest you add a cleanout for the path with the kitchen waste, since those tend to clog where the line turns from vertical to horizontal below the floor. The washer drainage would probably help to keep that clearer.
 

wwhitney

In the Trades
Messages
6,728
Reaction score
1,904
Points
113
Location
Berkeley, CA
Would not option B cause the vent for the utility sink to be "Wet" in the current configuration?
Yes, it would. Under the IPC (e.g. Michigan) the configuration shown would be allowed as an IPC911.3 common vent connected at different levels. The laundry standipe is 2 DFUs, so the pipe between the two san-tees only has to be 2". But there is the usual IPC 406.2 issue that below the laundry sink san-tee, the branch drain carrying both the laundry sink and the clothes washer needs to be 3". [The same is true in option A.)

https://up.codes/viewer/michigan/mi-plumbing-code-2015/chapter/9/vents#911.3

Under the UPC (e.g. Washington as in the OP), option B is not allowed as drawn. Vertical wet venting is limited to wet vents draining fixtures of 1 or 2 DFUs, and a washing machine standpipe is 3 DFUs. However, a laundry sink is only 2 DFUs, so if the laundry sink connects to the upper san-tee instead of the washing machine, that would be a UPC compliant wet vent. The pipe between the san-tees still only needs to be 2", as does the pipe below the lower san-tee.

https://up.codes/viewer/washington/upc-2018/chapter/9/vents#908.1

Cheers, Wayne
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks