Two lavatories are connected to a vertical 1-1/2″ drain pipe. The drain pipe routing is 2 feet down 17 feet horizontal and 12 feet down before it connects to the main drainage pipe. The same vertical pipe where the lavatories “tee” in also acts as a vent for the lavatories and a bathtub. However, the bathtub drain connection is 12 feet (2 feet vertically and 10 feet horizontally) downstream from where the lavatories “tee” in.
My question is: Should there be another vent closer to where the bathtub drain connects to the 1-1/2″ pipe. If so, where does it have to be? Based on the code it appears the maximum trap distance to the vent is 5 feet.
Replies
I may not fully understand the layout, but it sounds to me like you need two vents, one near the lavatories and another near the tub. The current vent is too far from everything that it is venting. I don't have the code book right here, but I'm sure all those distances are well over the limit.
That was my thought originally; however, after reading about wet vents I thought the 10 foot section could be considered a vent. I plan to add another vent. Does it matter where it goes? Can it go in the drain line directly from the bathtub or does it need to go between where the bathtub "tees" in and the lavatory drain?
I would put another vent for the tub
According to "Code Check's" plumbing field guide, if your bathtub has a 2" trap arm then here's the deal:
Maximum trap arm distance to vent -
- IRC = 8 ft.
- UPC = 5 ft.
Mike
Spot on.“A universal peace, it is to be feared, is in the catalogue of events, which will never exist but in the imaginations of visionary philosophers, or in the breasts of benevolent enthusiasts.” —James Madison
That was my thought originally; however, after reading about wet vents I thought the 10 foot section could be considered a vent. I plan to add another vent. Does it matter where it goes? Can it go in the drain line directly from the bathtub or does it need to go between where the bathtub "tees" in and the lavatory drain?
Does the code allow using Fernco plumbquik connections in vents?
Harold
Harold,
I'll start with the easy question about the Ferco's, yes, they're allowed.
"I plan to add another vent. Does it matter where it goes?"
Well, the closer to the trap arm the better, just not too close, but anywhere up to 8 ft. would still work.
"Can it go in the drain line directly from the bathtub or does it need to go between where the bathtub "tees" in and the lavatory drain?"
It can go in the drain line directly from the bathtub
"I thought the 10 foot section could be considered a vent"
I would disagree with that thinking. A "vent stack" is defined as a "vertical pipe" that provides air circulation for the drainage system. Key word here is "vertical pipe". If you're drain line is horizontal, then it's not considered a vent.
Mike
Thank you very much for answering my questions.
Harold
Sorry, I don't know US codes, but in Canada, a wet vent is different from a vent stack. And a wet vent can be horizontal. For that matter, so can a vent pipe.