Can a bathtub be vented thru the kitchen sinks drain

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Branimal

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I have a bathtub that needs to drain horizontally to the main stack. The stack is 14' from the tub's drain. I also need to make a 18' horizontal run for the kitchen sink. I'd like to drain both in the same pipe if possible.

The kitchen sink will be vented with a sanitary tee fitting at the wall. This drain line will then run in the walls to another sanitary tee (vented again for bathtub), and then down b/w the joists. It will wye into the bathtubs drain line.

So effectively the kitchen sink's drain line is acting as the bathtub's vent. Will this siphon water from the bathtubs trap?

All pipes are 2". Location is New York (IPC).
 

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John Gayewski

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Your drawing is kind of rough, well it's very rough.

A trap arm's vent needs to be level with its trap. Your drawing appears to show a large drop before venting through the sink.

A kitchen sink can vertically wet vent a bath tub. But horizontal wet venting is limited to bathroom fixtures. Though I'm less familiar with ipc I think these are the limitations. Someone else may have better advise.
 

Branimal

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Your drawing is kind of rough, well it's very rough.

A trap arm's vent needs to be level with its trap. Your drawing appears to show a large drop before venting through the sink.

A kitchen sink can vertically wet vent a bath tub. But horizontal wet venting is limited to bathroom fixtures. Though I'm less familiar with ipc I think these are the limitations. Someone else may have better advise.
I redrew the diagram. Hopefully it's a bit more clear.

The trap arm's vent starts with a wye rolled 45* upright. The wye is slightly higher than the trap. I'll do a mock up with some actual fittings and post a picture of it.
 

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Terry

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The bathtub needs a vent before joining the other line, and the vent is on top of the trap arm.

dwv_b2.jpg


The kitchen sink needs a vent on top of the trap arm, not below.

sink_dw.jpg
 

wwhitney

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E.g., as in the drawing below. Blue is 2" (recommended for a kitchen sink drain after the vent, but the IPC would allow 1-1/2"), which is all either vertical or horizontal; Green is 1-1/2", which is all either vertical, horizontal, or a trap; and Red is 1-1/2" at a rising angle.

The red can be the branch connection on a wye with horizontal barrel that is rolled 45 degrees off straight up. That puts the red rising at 30 degrees, and it should continue to rise at least that amount until under a wall where it can turn to with a 60 degree bend to go true vertical.

FWIW, the UPC would required the tub drain after the vent wye to be 2", not 1-1/2", but I understand the IPC allows 1-1/2".

Cheers, Wayne


IMG_4827 (2).jpg
 

John Gayewski

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I think that would be technically legal. I think that's technically a vertical wet vent. For upc you'd need that long wet vent to be 3".

There's likley a better way to do this.

The San tees you have on the way to the sink are not necessary.

Traditionally each of these two traps would have their own vent and the vents would be vertical until you get 6" above the flood rim of the fixture.
 

wwhitney

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I think that would be technically legal. I think that's technically a vertical wet vent. For upc you'd need that long wet vent to be 3".
The only verticals I'm reading on the 2nd isometric are the two vents and the tub and kitchen sink tail pieces (traps not shown). So I see a really long horizontal kitchen sink drain, and an attempt to horizontally wet vent the tub via the kitchen sink vent.

Cheers, Wayne
 

John Gayewski

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The only verticals I'm reading on the 2nd isometric are the two vents and the tub and kitchen sink tail pieces (traps not shown). So I see a really long horizontal kitchen sink drain, and an attempt to horizontally wet vent the tub via the kitchen sink vent.

Cheers, Wayne
The kitchen sink is a traditional kitchen sink with a tee. That's how I read it, but that does take a lot for granted. If that were the case the drain would be vertical,then turn horizontal. If that's not the case then yes I wouldn't call it a vertical wet vent.

Either way there's a better way.
 

Branimal

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E.g., as in the drawing below. Blue is 2" (recommended for a kitchen sink drain after the vent, but the IPC would allow 1-1/2"), which is all either vertical or horizontal; Green is 1-1/2", which is all either vertical, horizontal, or a trap; and Red is 1-1/2" at a rising angle.

The red can be the branch connection on a wye with horizontal barrel that is rolled 45 degrees off straight up. That puts the red rising at 30 degrees, and it should continue to rise at least that amount until under a wall where it can turn to with a 60 degree bend to go true vertical.

FWIW, the UPC would required the tub drain after the vent wye to be 2", not 1-1/2", but I understand the IPC allows 1-1/2".

Cheers, Wayne


Sounds like I need to run two horizontal drain pipes toward the main stack - one for the kitchen sink and one for the tub. That's fine. I was hoping I could consolidate. The pipes will run in parallel joist bays and join up near the stack with a wye and then run into the stack. Exactly what @wwhitney drew.

I have 2" cast iron pipe and 2" PVC. I find that PVC is a bit noisy when draining. Would you guys use the cast iron for the bathtub or the kitchen sink. There will be a dishwasher draining into the tailpiece of the sink's plumbing.
 
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