AAV Placement Confusion

nola000 · Sep 25, 2009

Hello.

Remodeling a bathroom. Im confused about the placement of an air admittance valve.

As you can see I have two options. Vent in the dry line above the sink or vent in the wet line between the tub and sink. I have a Black and Decker plumbing book that shows a picture of an AAV between two fixtures in a basement in the wet line with the fixtures above the AAV.

FloridaOrange · Sep 25, 2009

At the sink - that would give you a wet vent. Can you put an actual vent in at the sink and then route it to the vent through roof?

Rich B said:
Don't be to surpised if the answers you get are not very helpfull...LOL

?? What's up with that?

Sponsor · 2022-01-29T12:20:58-0800

nola000 · Sep 25, 2009

"At the sink - that would give you a wet vent."
I dont get it. How does putting an AAV on a tee above my sink make that a wet vent? If my AAV is getting wet then it probably wont be very effective. Are you saying I should place it in that location? If so, then what is wrong with placing it below the floor in the wet drain between the tub and sink?

I can vent to the attic, but I cant connect to the stack in the attic. That is why I wanted to do the AAV.

SewerRatz · Sep 25, 2009

If you are going to use an AAV you need to put one on each fixture. FYI AAV are not allowed in the state of Louisiana. Here is a list of what stats approved the use of AAV's and the ones that have not. http://www.studor.com/approvals.htm

Terry · Sep 25, 2009

I would like to see the shower vented, and tied back into the lav vent.
The revent can be above the flood level of the lav plus six inches.
If you are planning on "wet venting" the tub with the lav, I would move the wye closer to the tub, it will drain and vent better with less pipe.
The pipe for the lav needs to be 2" and the trap arms for the lav and tub can be 1.5"

If you use an AAV, it must be accessible.
That means if you put it in a wall, it must have a grill to allow air.

If the walls are open, your best option would be to vent the fixtures with pipes, and run that pipe through the roof.

An AAV will fail at some point.

Rich B · Sep 25, 2009

FloridaOrange said:
?? What's up with that?

Most of the time many posters on here are pretty tough on someone who even hints about using an AAV, was my meaning there......There are a few that are really tough to please and they mostly offer only negative comments and very little actual help other than "call a plumber"......

nola000 · Sep 25, 2009

How would I vent the shower? Its got 2" pipe and the trap for it is about one foot from the main vent stack. Do I really need to vent it separately?

How would I tie it back to the lav vent? What lav vent? I dont have one yet Im trying to put an AAV on it.

I already ran the pipe for the lav. at 1.5". Can I get away with that or is it absolutely necessary I move to 2"?

If I go with the AAV in the wall above the lav. I will probably run it all the way up to the attic so I can access it when its time to change it.

Im aware of the failure of the flaps in the AAVs but I dont mind crawling into my attic once every few years to unscrew a thingamajig and screw in a new one. People do that all the time already and sometimes more often...your typical household light bulb.

You mention wet vent. Can I put the AAV under the house inline between the tub and lav like proposed in the diagram I linked to? That would be the easiest for me.

I thought because the shower was so close to the main vent stack that I didnt need to vent it separately. Is that not correct? And I didnt mention on the diagram but the shower plumbing is 2".

SewerRatz · Sep 25, 2009

nola000 said:
How would I vent the shower? Its got 2" pipe and the trap for it is about one foot from the main vent stack. Do I really need to vent it separately?

How would I tie it back to the lav vent? What lav vent? I dont have one yet Im trying to put an AAV on it.

I already ran the pipe for the lav. at 1.5". Can I get away with that or is it absolutely necessary I move to 2"?

If I go with the AAV in the wall above the lav. I will probably run it all the way up to the attic so I can access it when its time to change it.

Im aware of the failure of the flaps in the AAVs but I dont mind crawling into my attic once every few years to unscrew a thingamajig and screw in a new one. People do that all the time already and sometimes more often...your typical household light bulb.

You mention wet vent. Can I put the AAV under the house inline between the tub and lav like proposed in the diagram I linked to? That would be the easiest for me.

Maybe you missed what I posted above, so I will post it for you again. AAVs are not allowed in the state of Louisiana. Here is a list of what states approved the use of AAV's and the ones that have not. http://www.studor.com/approvals.htm

So you are going to have to run the vent to the attic and cut into the existing vent stack and tie it in there or run the vent though the roof.

NHmaster · Sep 25, 2009

The AAV should be placed thusley,

nola000 · Sep 25, 2009

I plan on dying in this house. I dont plan on ever having and inspector in my house. It will probably be a knock down by the time I die. Assuming the house is not in Louisiana can I do what I proposed?

SewerRatz · Sep 25, 2009

Yep I love giving plumbing advice to people that do not want to follow it, or the code. Just because you plan on living there till you die does not mean you do not need to follow the plumbing codes. They are there for your protection as well as your community.

nola000 · Sep 25, 2009

I certainly appreciate your advice.
I dont live in a gated community or a neighborhood. I live in the middle of nowhere, my closest neighbor could scream bloody murder in the still of the night and I would never hear it.
I understand the reason for code in areas where your mistakes could affect your neighbors. This is not one of those areas.
Like I said I appreciate any advice from an expert like yourself but if your conscious and duty to the plumbing profession cannot in good faith allow you to help me with my problem then I completely understand.

Mad Plumber · Sep 25, 2009

I was able to Google his home address.
Now I understand, that roof and attic look pretty tough.

nola000 · Sep 25, 2009

What is my home address?

Joe the Plumber · Sep 25, 2009

I'm lost here.
Waht are we talking about?

I can put vents throu steel roofs.
But I don't like werking arund dogs.

Mad Plumber · Sep 25, 2009

Teh roof, where is the 4" vent?

Is this an old vent, or is it a vent for plumbing under the bathrom?
Whey do you have a pipe going throgh the roof?
If it's a vent for below stuff, you cant put poop and sutff down it. right.

So maybe it is just a pipe throght your roof. for no reason?
Bjut I want to know, what in teh world is that pipe doing therfe all by itself?

vent? or waste?
Whiat is it?

nola000 · Sep 26, 2009

Its an old iron pipe that runs vertically up through the roof. Near the bottom, all the fixtures in the bathroom tie into it. Then at the very bottom is a cleanout with a plug and then a horizontal pipe that is half buried and runs to the septic tank.

hj · Sep 26, 2009

aav

Each sink must have its own vent whether a conventional one or an AAV. A single aav will not take care of both sinks the way you have it drawn. The shower drain is also susceptible to problems because of the Bournelli Effect caused by water flowing past its connection. In general, ANY drain that turns downward after the trap needs a venting method before it turns downward.

nola000 · Sep 26, 2009

You mention two sinks. I dont have two sinks. In order I have a vent - shower - sink - tub.

You also mention Bournelli effect because of water movement past the shower connection. Does it matter that the connection is a wye and not a tee? Also, this effect that you mention, does it only occur when the other fixtures upsteam(tub, sink) from it are draining water? Chances are I wont have the sink or tub draining at the same time as the shower very often.

I have read many times that a single AAV can serve multiple fixtures. In what way are they referring to?

How do you place a vent before the down turn on a clawfoot tub that has exposed overflow/drain assembly?

Can somebody draw suggestions on my diagram and post it? I would like to use AAVs if possible.

hj · Sep 26, 2009

drain

I guess your drawing is so large that I misinterpreted it as I scrolled sideways to see the entire thing. The leg tub will be vented by the lavatory AS LONG as its trap is on the same plane as the horizontal drain line. The shower is the one that is questionable.

AAV Placement Confusion

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