Relocating a washer to a closet with second story above so no practical standard venting routes out through roof. So, if allowed, I think a bow vent will let me get to the old location vent stack that served only the washer. If searched the web but found no references to bow venting a washer drain. Seems similar to an island sink setup. Is it allow assuming I follow the bow vent rules?

Thanks
Dave

California Plumbing Code 909.1 lists island sinks and similar equipment as acceptable uses for an island/loop/bow vent. This type of vent is not for convenience, but necessity. I doubt an inspector would allow it for your clothes washer.

obviously the person to ask is the inspector.

Steve, thanks for the CPC reference. Upon reading it several times, I keep wondering what the intent of the wording "similar equipment" is? Plus the section 900.0 is titled "Special venting for island fixtures " and isn't a clothes washer drain a fixture? However, like you, I believe the inspector would likely not interpret the code in my favor and thus disallow clothes washer bow venting. From a theoretical point of view though the bow vent seems as sound on a washer drain as it does on an island sink. Do you agree?

Thanks
Dave

Once I asked if I could use a loop vent in a peninsula (it would've made things much easier) and the answer was no. Loop vents are only for islands. At least that's what my inspector told me at the time (this was years ago).

Probably the reason the inspector is not going along is that the laundry drain gets water pumped through it and venting is critical to not have overflows. My guess is that a clothes washer pumps more than a garbage disposal discharges, otherwise kitchen sinks would call for a 2" trap. Make sense?

for bow venting a kitchen, they do like to see 2 inch drain and vent. the trap arm can be reduced to 1 1/2..

Good point about the forced discharge of the dishwasher through the disposal. Might be a little less than a clothes washer but not by much. Using 2" vent will provide extra margin for a washer. I was planning 1 1/2" venting but after this discussion, I'll increase to 2".

Thanks for all the responses and insight into this topic.
Dave

The vent doesn't need to be 2". Code minimum is ½ the drain diameter, and no smaller than 1¼". The vent keeps the trap from siphoning and a 4" vent won't make the drain flow any better than an 1½".

DON'T

'google' suds pressure zone

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

Indeed 1 1/2" is adequate vent dia for 2" drain. However, I noticed a phrase in the IPC 916.2 code that states "The lowest point of the island fixture vent shall connect full size to the drainage system." My interpretation of this is that for a 2" drain the vent diameter from the san-tee up through the bow portion and back to the drain must be 2". The VTR could be 1 1/2".

California has it's own Plumbing Code, it's not the IPC. There's also wording that the vent shall run to the nearest partition and then turn vertical, with a cleanout in the vertical. Are you going to do that? If you're not going to follow the CA Code as written, why not use an AAV(which are also illegal in CA)and forget about all the extra piping? Or have you checked with your local inspector to see if he/she will allow the island vent as you propose to do?

The W/D relocation project is in my daughter's recent home purchase. While I'm wanting to comply with the local codes as close as possible, an inspector will not be involved here. With that said I'm still striving to build a trouble free setup without ripping apart several walls trying to VTR. The AAV certainly simplifies the vent plumbing or building construction rework but IMO has more potential reliability issues than an optimized island fixture vent system.

I do plan on conforming to "island" fixture venting code completely and was thinking the IPC was more rigorous than CPC in terms of the vent sizing as it returned to the waste drainage system. I could drop to 1 1/2" for the route to the "nearest" partition, up through the wall (with C/O) and VTR. But since the existing washer location is vented to roof with 2" I thought I'd just use 2" all the way. BTW, this fixture in individually vented plus its the last fixture on the drainage system.

Thanks,
Dave