Two Washing Machine Hookup - Vent Question

[MarktheRed]

Family is growing large enough that we need to have two washing machines to keep up.

Currently they are draining into a utility sink, and there has been no issues with draining capacity. Looking to the plumb in a proper wall drain, and just wanted some feedback on the best way to do it. It would be significantly easier to use one drain / hookup for both, and i know the code says a 2" drain per machine. That said a 3" drain has slightly less area and will be significantly less work to plumb. Is what I drew below correct from a venting standpoint? Appreciate the feedback. Chicago area suburbs. Not getting an inspection.

 

[Reach4]

A 3-inch pipe has more cross sectional area than two 2-inch pipes.

Area is proportional to the square of the diameter.

 

[Sponsor]

 

[John Gayewski]

You should tie each two inch trap arm into 3 inch pipe if your wanting to use 3" anywhere.

3 inch fittings won't fit in most walls unless your planning on building a wall from 2x6's and even then a trap in the wall being 3" is pretty odd. The fitting where each trap arm ties into the drain should be a double fixture fitting (3x3x2x2).

If your trap arm is longer than 8' you'll need to vent it, otherwise (as long as the is no other waste coming from above) the trap arm's are vented. 2" is fine for the vent.

 

[MarktheRed]

You should tie each two inch trap arm into 3 inch pipe if your wanting to use 3" anywhere.

3 inch fittings won't fit in most walls unless your planning on building a wall from 2x6's and even then a trap in the wall being 3" is pretty odd. The fitting where each trap arm ties into the drain should be a double fixture fitting (3x3x2x2).

If your trap arm is longer than 8' you'll need to vent it, otherwise (as long as the is no other waste coming from above) the trap arm's are vented. 2" is fine for the vent.

Thanks for the feedback (and @Reach4) Its against a basement wall with some insulation buildout so I could make it fit with 3" What is the alternative? Two completely different 2" trap without vent like you describe. See below is what I understand based on your description. I know the traps aren't to scale, I just crudely sketched this in CAD. There is no other waste coming from above.

 

[Reach4]

How would you like things positioned-- like your first picture? Your first picture only had two traps. Do you want 2 traps or 3?

If so, how about bringing in the vented drain from the left trap right to the 3-inch? Or make the bottom wye 3 inch, and feed that from another wye... I could go into that more if you like.

 

[MarktheRed]

How would you like things positioned-- like your first picture? Your first picture only had two traps. Do you want 2 traps or 3?

If so, how about bringing in the vented drain from the left trap right to the 3-inch? Or make the bottom wye 3 inch, and feed that from another wye... I could go into that more if you like.

Personally, I like having one washing machine hookup / drain rather than two. Its just less chance of something going wrong, and 3" traps / drains dont bother me because I will be framing at the same time I am installing this. Due to various other crap in that wall (wall is sloped slightly, I am attaching XPS to the concrete before framing, I have no problem putting in 3" plumbing because the 2x4 studs will be offset sufficiently. I am just concerned about the venting for two washing machines with two parrallel 2" drains / traps. The cost of the 3" piping is pennies compared to the carpentry challenges with two parrallel 2" pipes; plus I don't see how to vent both 2" pipes without connecting the lower 2" to the upper 2" that will end up short circuiting. Maybe I am overthinking this.
You're the expert Reach4. Tell me how dumb I am. What would you do it it were your wall?

 

[Reach4]

Not the expert.

Do you want 2 traps or 3?

 

[MarktheRed]

2 traps

 

[Reach4]

Crude markup, but wye in 3 inch with 2 inch side. That connects to 3 inch wye with the two incoming ports bushed down to 2 inches.

Vent, lower part of the green... Combo is OK, but maybe a sanitary tee would be OK. It would be in IPC but not UPC. I don't know about IL code.

I am sure there are other alternatives.

 

[Jeff H Young]

I dont see anything wrong with a 3inch laundry standpipe for dual machines? if Markthered finds it easy to plumb I like it !

 

[wwhitney]

basement . . . There is no other waste coming from above.

Just double checking the above--in an existing home, it would be pretty unusual to find a 4" stack rising from the building drain up through the roof that doesn't carry drainage from an upper floor. That's definitely what you have?

Cheers, Wayne

 

[MarktheRed]

Just double checking the above--in an existing home, it would be pretty unusual to find a 4" stack rising from the building drain up through the roof that doesn't carry drainage from an upper floor. That's definitely what you have?

Cheers, Wayne

I probably didn't explain myself well. The 4" pipe is definitely taking sewage from the above. I am not tapping into that. There is a 2" line behind the main 4" that all connections will go to. Both the 4" and 2" have vents above. See the picture. Hope its clear. The spray foam abomination on the wall is not mine, from the previous owners of the house doing some DIY waterproofing at the window buck. The sink is being trashed and moved. Currently using to drain the two washing machines.

PS: I had a bunch of database errors trying to access this site so my answers are a bit late. appreciate the help.

*Also the 2" line behind the 4" main is getting ZERO water from above. Its from an old laundry room upstairs that was drywalled over. Its defintely venting to the roof as I did some attic work last year and saw it up there. The 2" line going to the right is just a drain for the AC condensate (overkill). Hope this helps.

 

[MarktheRed]

if Markthered finds it easy to plumb I like it !

not sure if I am walking into a buzzsaw. Is 3" plumbing a nightmare to source / work with notwithstanding the thickness issue?

 

[wwhitney]

*Also the 2" line behind the 4" main is getting ZERO water from above.

Ah, OK, that 2" works for a dry vent for everything.

So one downside of your 3" trap plan is that you have to cut into the 4" stack to add a 4x3 san-tee or wye to receive the 3" drain line. Whereas if you stick with 2" you can just reuse the existing 2" stack. Sticking with 2" would either mean putting both washing machines into the laundry sink; or putting one into the sink and adding one standpipe and trap; or adding two standpipes and traps.

But either way works, as long as you vent each fixture properly.

Cheers, Wayne

 

[MarktheRed]

Ah, OK, that 2" works for a dry vent for everything.

So one downside of your 3" trap plan is that you have to cut into the 4" stack to add a 4x3 san-tee or wye to receive the 3" drain line. Whereas if you stick with 2" you can just reuse the existing 2" stack. Sticking with 2" would either mean putting both washing machines into the laundry sink; or putting one into the sink and adding one standpipe and trap; or adding two standpipes and traps.

But either way works, as long as you vent each fixture properly.

Cheers, Wayne

I tried to simplify my original venting request for the sake of your time. Its worse than I let on. All of those vent pipes are actually 1.5" and the main is 3" (not 4"). So to do this right, I'm going to have to get dirty either way and do some major plumbing rework. I put in the picture some quick notes that probably are hard to see. I might just tie directly into 3" with new washing machine drain and vent to the 1.5" stack like Reach 4 sketched up.

 

[MarktheRed]

Draining to the sink is on longer bueno. Wife wants pic related this as part of the new laundry room. I will modify to have a single 3" pipe hole (not the 2" in the stock).

 

[Reach4]

ABS is less common in Illinois than PVC, so you may have to order stuff.... not a big deal.

1.5 inch vent seems to be fine with IL code. https://ilga.gov/commission/jcar/admincode/077/077008900K15800R.html says "Size of Individual Vents. The diameter of an individual vent shall be at least 1¼ inches or at least half the diameter of the drain to which it connects, whichever is greater. "

 

[Jeff H Young]

not sure if I am walking into a buzzsaw. Is 3" plumbing a nightmare to source / work with notwithstanding the thickness issue?

abs is easy to get if 2 inch passes your code go 2 inch if you prefer

 

[John Gayewski]

abs is easy to get if 2 inch passes your code go 2 inch if you prefer

You'd have to order abs here. Illinois isn't much different, possibly in some bigger cities it's easy to get, but not around here (I live on the iowa/illinois border).

Chicago is it's own world when it comes to plumbing. They were one of the last ones to allow plastic dwv of any kind. Their code test requires a practical where you must poor a lead joint. Although I've been told that changed in recent years.

 

[Jeff H Young]

You'd have to order abs here. Illinois isn't much different, possibly in some bigger cities it's easy to get, but not around here (I live on the iowa/illinois border).

Chicago is it's own world when it comes to plumbing. They were one of the last ones to allow plastic dwv of any kind. Their code test requires a practical where you must poor a lead joint. Although I've been told that changed in recent years.

One of the last to allow no hub too i think i heard they were all lead and oakum in the early 90s i think I guess on commercial they allow no hub and dont require hubbed pipe ?