Old bathtub in a very old home did not have a vent. The drain went through the outer wall of the house down 2 floors to the basement where it connected to a P-trap before entering the main waste line which exits to the septic tank. Most of the time the tub drained without issue. Occasionally I'd hear gurgling sounds which I think was due to either S-trap siphoning, or water momentum emptying that P-trap in the basement. I've since tapped a vent into the main stack and vented all fixtures in the house. I'm sure the answer to my next question will be "it's not to code". But, if I disconnect the P-trap in the basement, and repurpose it by connecting it to the nearby branch vent, would the pipe going up thru the wall be a sufficient 1-1/2" vent pipe I could then use to vent the bathtub drain? Note that the drain is being relocated to wye into the main stack.



Edited 3 times.

i'd take the easy way out.

try removing the p-trap and replacing with a drum trap.

it's not to code but it's a heck of alot better than what you have.

in the bottom and out the top.

[www.homedepot.com]

I'm changing the drain from down the outer wall of the house to the stack, so now I need to install a vent just after the new P-trap at the bathtub. If I remove the P-trap in the basement and connect that (formerly used drain) pipe to a branch vent, are there any issues using a vent pipe 2 floors up from the basement as the vent for this bathtub fixture?

vents need to go UP not down

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

we do use "island vents".

done properly they work and pass code.

[www.google.com]

but NOT floor to floor

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