Laundry room drains - washer and sink on same drain with AAV

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Zwaanty

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Hi,

I'm finishing the above-ground drains for a washing machine and laundry sink. I've read through forums and have sketched out an idea - looking for input on whether it will be vented properly, and if I need a clean-out. In the images, the blue pipes are below concrete and were done by plumbers this summer - green pipes are what I am proposing.

Specific questions:
1. Can I use a double fixture tee instead of two separate sanitary tees? This would save me vertical space that is tight to get low enough for the laundry sink drain.
2. Should I add a second air admittance valve right after the laundry sink p-trap? (I'm not able to vent to the outside/main vent, so aav's are my only option)
3. Is a cleanout required anywhere?

Thanks!

Washer & Laundry Sink Plumbing.jpg
Bathroom Plumbing layout.jpg
 

Terry

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Neither the washing machine or a laundry tray can be part of a wet vent.
How is the bathroom downstream vented? Venting will be needed for the toilet, lav and tub.

Looking at the washer and laundry tray, you can't wet vent a sink with a washer. The washer gets pumped out and would siphon the sink trap dry. You could use a 2" double fixture fitting, but I have never done that, as I would worry that the washer would still skip across the fitting and over toward the sink. Normally I vent those two fixtures separately and then tie venting back, six inches above the flood level of the fixtures served.

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wwhitney

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Neither the washing machine or a laundry tray can be part of a wet vent.
That's what we're used to in the US. Apparently the Canadian plumbing code allows a limited number of separately vented DFUs to drain through a wet vent. Not sure what the limit is, and whether a laundry standpipe plus a laundry sink would exceed the limit or not.

Cheers, Wayne
 

Zwaanty

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Thanks so much for the feedback!

The bathroom downsteam will be vented temporarily with an AAV, and then when renovations are continued next year on the upstairs bathroom, venting will be tied into the main vent that goes to the roof.

For the washer and laundry tray, hopefully I've understood the wet venting problem properly - would either/both of these options below solve the problem?

Thanks again :)

Option A - a second AAV directly under the sink with the same plan as proposed - similar to this picture?

aav with sink.jpeg



Option B - venting both fixtures separately but connecting to the same AAV

Version 2 - Washer & Laundry Sink Plumbing.jpg
 

Reach4

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I think your second drawing may or may not do it for Canada but make one or 2 changes and you would be very good:
1. Invert the top santee.

2. Put the left santee vertical, and put a long sweep 90 under it. Then bring vent into the top of the santee.
Alternate for #2: put the santee at 45 degrees, and have a 45 above and below the santee.

I think Canada wants the AAVs to be 6 inches above the flood level (top of standpipe)
 
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wwhitney

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The bathroom downsteam will be vented temporarily with an aav, and then when renovations are continued next year on the upstairs bathroom, venting will be tied into the main vent that goes to the roof.

For the washer and laundry tray, hopefully I've understood the wet venting problem properly
No, the issue has nothing to do with the venting of the laundry and the laundry sink itself. It has to do with where the combined laundry drain joins the bathroom drain. In the US, it would have to join downstream of all the bathroom fixtures to allow the bathroom fixtures themselves to use wet venting, which is what you've shown.

In Canada, I recall an allowance for some unrelated fixture to flow through the bathroom's wet vented drains. So you need to check the Canadian rules on that to determine whether you'd need to move the laundry drain's connection to the bathroom to further downstream. If the under slab plumbing was done by professional local plumbers, then hopefully they got it right and the Canadian plumbing code does allow both the laundry standpipe and sink to flow through the bathroom's wet vented drains.

Your drawing has a couple issues--you can't use a san-tee on its side like that, and a dry vent takeoff has to be above the drain centerline, not horizontal.

Cheers, Wayne
 

Reach4

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This works also. Wye+45, or combo always OK for the sink vent. In some codes, a santee on its back could be used for venting the sink.
 

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Zwaanty

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No, the issue has nothing to do with the venting of the laundry and the laundry sink itself. It has to do with where the combined laundry drain joins the bathroom drain. In the US, it would have to join downstream of all the bathroom fixtures to allow the bathroom fixtures themselves to use wet venting, which is what you've shown.

In Canada, I recall an allowance for some unrelated fixture to flow through the bathroom's wet vented drains. So you need to check the Canadian rules on that to determine whether you'd need to move the laundry drain's connection to the bathroom to further downstream. If the under slab plumbing was done by professional local plumbers, then hopefully they got it right and the Canadian plumbing code does allow both the laundry standpipe and sink to flow through the bathroom's wet vented drains.

Your drawing has a couple issues--you can't use a san-tee on its side like that, and a dry vent takeoff has to be above the drain centerline, not horizontal.

Cheers, Wayne
Thanks so much for this clarification. I'm going to go with the assumption that since professional plumbers did the under slab work and were aware of the plans for laundry, the wet venting of the bathroom drains is good to go with Canadian code.
 

Zwaanty

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This works also. Wye+45, or combo always OK for the sink vent. In some codes, a santee on its back could be used for venting the sink.
Thanks so much! The visual is very helpful for clarifying.
 
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