Understanding Horizontal Wet Vent

[Hallowhead1]

Howdy,

I am just trying to better understand if I installed the plumbing / vent in my house correctly. I believe it follows a horizontal wet vent. Let me know - I can tell you the plumbing works as it's been installed for a year now.

 

[wwhitney]

The bath tub is definitely wrong for wet venting, the trap is too high. The wye below your "bathtub" label would be your tub vent connection, but the tub's vent connection is required to be no more that one pipe diameter lower than the trap outlet. So the tub trap arm can't turn down before the wye, and needs to enter the wye horizontally.

Also, you need to check whether the NSPC (NJ's plumbing code) allows the WC to be upstream of the tub, or not, on a horizontal wet vent. The IPC does, and the UPC doesn't, but NJ has its own plumbing code.

Also, what's connected on the left where it says lav branches off? If the only fixture that drains into that is the lav, then that works for wet venting the WC (as is) and the tub (if the above issues are resolved). But if you have any non-bathroom fixtures draining into that stack, or any fixture from a story above the bathroom, then that doesn't work for wet venting the tub and WC. You'd need to keep the lav drain separate from the other fixtures, use it to wet vent the WC and tub, and then the bathroom branch drain could join the other fixtures.

Cheers, Wayne

 

[Sponsor]

 

[John Gayewski]

Looks to me like you would have had an easier time if you offset the stack before you started.

 

[Hallowhead1]

The bath tub is definitely wrong for wet venting, the trap is too high. The wye below your "bathtub" label would be your tub vent connection, but the tub's vent connection is required to be no more that one pipe diameter lower than the trap outlet. So the tub trap arm can't turn down before the wye, and needs to enter the wye horizontally.

Also, you need to check whether the NSPC (NJ's plumbing code) allows the WC to be upstream of the tub, or not, on a horizontal wet vent. The IPC does, and the UPC doesn't, but NJ has its own plumbing code.

Also, what's connected on the left where it says lav branches off? If the only fixture that drains into that is the lav, then that works for wet venting the WC (as is) and the tub (if the above issues are resolved). But if you have any non-bathroom fixtures draining into that stack, or any fixture from a story above the bathroom, then that doesn't work for wet venting the tub and WC. You'd need to keep the lav drain separate from the other fixtures, use it to wet vent the WC and tub, and then the bathroom branch drain could join the other fixtures.

Cheers, Wayne

If only that tub trap would go lower - it's kissing the 3" as it is. If it was upsized would it be able to turn down as mentioned ?

Where it says lav branches up that 3" goes up and my lav wyes off then converts to 4" and picks up my WC and another lav on the 2nd floor.

 

[John Gayewski]

If only that tub trap would go lower - it's kissing the 3" as it is. If it was upsized would it be able to turn down as mentioned ?

Where it says lav branches up that 3" goes up and my lav wyes off then converts to 4" and picks up my WC and another lav on the 2nd floor.

Yeah this is not a wet vented system that would pass inspection I would expect more problems.

 

[Weekend Handyman]

I am not a plumber or pro.

My homeowner take is this ... Do you plan on finishing the space? If not, just wait and see what happens ... a year of daily use is pretty good run time.

Just take what you learn and know more for the next time.

 

[Hallowhead1]

I am not a plumber or pro.

My homeowner take is this ... Do you plan on finishing the space? If not, just wait and see what happens ... a year of daily use is pretty good run time.

Just take what you learn and know more for the next time.

I'll probably finish the walls but ceilings will remain open in the new year, it runs great. I've consulted with commerical plumbers as I work in core and shell construction, too which they said the shit will flow it just wouldn't pass code.

I just want to see what would make it "right" so as you said I can learn.

 

[Hallowhead1]

Bump

 

[wwhitney]

If only that tub trap would go lower - it's kissing the 3" as it is. If it was upsized would it be able to turn down as mentioned ?

No. To wet vent the tub, you need to lower the trap, so either offset (with two 45s) the tub tailpiece, or better offset the 3" stack against the block(?) wall.

Where it says lav branches up that 3" goes up and my lav wyes off then converts to 4" and picks up my WC and another lav on the 2nd floor.

Right, so as I indicated, that lav branch for this bathroom should be kept separate from the 3" stack. The lav should join the tub and WC to wet vent them (with the previous proviso about checking what NJ has to say about the order that happens in). Only then should the 3" bathroom branch join the 3" drain from the 3" stack.

Also, if the above description is going upstream, you can't convert from 3" to 4". That would mean a 4" drain becomes a 3" drain, which is not allowed. Once you have 4", everything downstream has to be 4".

Cheers, Wayne