Placement of two AAVs

[TunaBreath]

A friend found out that her vanity and tub drain are not vented and asked if I could take a look at it. I am thinking of adding two AAVs, one in the vanity cabinet (if i have enough room since its a P trap and not an S trap and there isn't much of a stub out). I am also thinking of adding one on the tub drain trap arm and should hopefully be able to get the AAV at least 4" above the trap inside the joist cavity. What do you guys think? Do you see any other suitable/better locations. I'd rather not run a true vent out the side of the house because I don't want to penetrate the roof (flat roof).


Looking at my photos, if I can't get the tub AAV above the trap level in the joist cavity, would it be possible to just cut and add a wye or san-t downstream from the tub trap and then extend from the wye out to the side of the house and up above the roofline (going around eave, not pretty)?

If I can't get an AAV in the vanity cabinet, I may have to do the same as the tub.

I don't want to hack this up but they also are not willing to let me tear open walls and cut holes in the roof.

 

[Reach4]

Why do you think the lavatory is not vented already?

See Rector Seal Magic Trap. Needs their AAV
https://www.supplyhouse.com/Rectorseal-97402-Magic-Trap-Tubular-Fitting-w-Tee

For the tub, remember you have to have 4 inches up to the AAV, and you have to be able to replace the AAV. But if you can do that, your plan works.

 

[Sponsor]

 

[Tuttles Revenge]

And while you're replacing that Tee with a Wye.. replace the double 90s after the tub trap/vent with a 90 at a 45 and 45 elbow.. currently there are 2 medium sweep 90s.

 

[TunaBreath]

Why do you think the lavatory is not vented already?

See Rector Seal Magic Trap. Needs their AAV
https://www.supplyhouse.com/Rectorseal-97402-Magic-Trap-Tubular-Fitting-w-Tee

For the tub, remember you have to have 4 inches up to the AAV, and you have to be able to replace the AAV. But if you can do that, your plan works.

Lav is not vented, I saw no penetrations in the roof and saw no likely place where it would be tied into another existing vent.

That Rector Seal product looks nice but I'm not sure if I will have the room in the vanity cabinet with the short stubout from the wall.

As for the tub vent, If I can't get 4" above the trap in the joist cavity, can I still place a san-t in the trap arm and then route that backwards and locate the AAV in an area above the trap but still accessible, such as behind the tub overflow?

 

[Reach4]

Sometimes with a p-trap, the trap arm goes past the tailpiece and the U turns back to the tailpiece.

 

[Reach4]

Lav is not vented, I saw no penetrations in the roof and saw no likely place where it would be tied into another existing vent.

You really should have a vent-thru-roof. You are not allowed to vent with all AAVs.

I wonder if your vent just opens into the attic. Weather is about as good as it gets for checking out the attic. Do not wait until August.

 

[TunaBreath]

Can I use the above setup to vent the tub? I would place the AAV behing the tub where it still would be accessible from the basement.

 

[TunaBreath]

You really should have a vent-thru-roof. You are not allowed to vent with all AAVs.

I wonder if your vent just opens into the attic. Weather is about as good as it gets for checking out the attic. Do not wait until August.

I'll look closer from the basement area to see if it is vented but a plumber has already been there to clear a main line pluggage and claimed there's no vent.

 

[Reach4]

Can I use the above setup to vent the tub? I would place the AAV behing the tub where it still would be accessible from the basement.

No. The vent pipe must stay within 45 degrees of plumb until at least 6 inches above the tub rim.

 

[TunaBreath]

No. The vent pipe must stay within 45 degrees of plumb until at least 4 inches above the tub rim.

If AAVs always had to be placed above the fixture rim then much of the appeal of using them would be lost? In an earlier post of yours you showed an image which doesn't have the AAV placed above the fixture rim.

 

[Reach4]

If AAVs always had to be placed above the fixture rim then much of the appeal of using them would be lost? In an earlier post of yours you showed an image which doesn't have the AAV placed above the fixture rim.

The AAV does not have to be above the flood level. The pipe to the AAV cannot go horizontal below 6 inches above the the flood level. The under-sink installations you have seen have the pipe to the AAV vertical (within 45 degrees of plumb). In the attached sketch, the pipe goes up at 45 degrees, and that is considered vertical. It does not have a horizontal section.

As I understand it, Canada wants the AAV above the flood level, but IPC does not require that.