Air Admittance Valve instead of vent pipe?

[cc-rider]

I'm reading, but I don't understand.
I understand that I can put an AAV on the vanities, kitchen sink, etc., because they are "exposed" to the air under the sinks. But, if I understand correctly, I can also use an AAV on a toilet and bathtub IF I put the AAV on the vent pipe in the wall with a louvered cover into the room. Is that correct? Does that eliminate having the 4" vent through the roof??

[agmantoo]

http://www.google.com/search?q=struder+vent&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a
http://www.studor.com/approvals.htm

[cc-rider]

Thanks for that approval chart! I had already looked at the other site and that's where I got the info. Do you have any idea why the AAV has to be boxed in if you use it in the wall? Do you think they are afraid it will suck in insulation or something? I'm wondering if I can just run a couple 2x4s between the existing studs to frame it in and then just put a vented grate (like a cold air return grate) over an opening in the wall directly in front of the AAV?

I'm thinking that I could use something like this for the toilet and tub, but run a vent line up as high as the ceiling, put the AAV just below the ceiling level, and put a grate over it. It wouldn't be as obvious up that high...probably would just look like an air return.

Think that'd work?

[tamsam]

Well where does this valve attach to the sink tub ect? I don't know if I would want it venting into the house. A vent is susposed to let air out of the septic system and also let water drain faster. If on a city system it might be ok if it doesn't vent back out into the house. Just my thoughts. Sam

[cc-rider]

I don't think it lets air "out"....it really just sucks it in. On a sink, it goes right behind the p-trap, I believe. It draws it's air from the house air.

[Harry Chickpea]

Remember that many times the way serious clogs can be cleared out are by inserting a power snake in the roof vents. That keeps the mess and smell out of the house and makes for long clear runs.

[cab]

They are one way valves that admit air into the plumbing systems to keep the trap water from being sucked out. They are not allowed in many states. They need to be installed where they can be inspected and replaced because they do fail. Most people don't bother maintaining them and that is why they have problems....

[tamsam]

I still don't think that this system would work on a home septic tank as they gas off so water can drain. Sam

[cc-rider]

I already had my main stack vent through the roof, so it doesn't make sense to NOT use it, but I think I'm going to use an AAV for the kitchen sink (island...and impossible to vent!), and possibly the upstairs vanity since it's on a different wall from everything else in the house and I'd have to go around a corner and a window. It's just nice to know there are options.

[farminghandyman]

a real vent is better, and prefered.

how to do a real vent on an island sink
http://www.rd.com/how-to-plumb-an-is...icle19540.html

the AAV will give out in time and cause problmes, and many codes do not allow them,

[cc-rider]

"Drawbacks? Sometimes AAVs can’t keep up with the venting needs of high-volume (18 to 22 gpm) discharge washers and dishwashers. And AAVs have a tougher time relieving pressure in the drainage and vent system of five-story buildings and higher."

I don't have a high-volume discharge washer, nor a dishwasher, and my house is 1-1/2 stories. I'll bet I'll be ok.

[Ross]

There are newer types avaiable now that are supposed to be up to code and function better. I'm using two (we have a main stack ) for two small branch lines. If price matters they are almost 3x the cost of the traditional ones. I'll get a name and post it after I visit the house I'm working on.

[cc-rider]

I saw some 2" ones at Menards for $19. That isn't bad considering the cost of the vent line you'd save, I guess.