AAV question

First problem: We just bought a house with some questionable plumbing issues. In the kitchen we have a two-basin sink. The piping below was assembled haphazardly by the previous owner. There was no drainage - i.e. When you ran the water in one basin, the other would fill up and then both would drain extremely slowly.

We had a plumber come to do other work, and he stated that it appeared that it wasn't vented - the kitchen was remodeled and they probably didn't tap into the venting.

So, we decided to correct the sink on our own. We reviewed lots of info and re-structured the piping how it should be. We added the AAV. When we turned the water on, it was fine for a few seconds, and then leaks started to come out of every "joint" area, and the basins began backing up.

I unscrewed the AAV a bit, and that "loosened" things up to let the water drain. We assumed that it was just the problem. So, we wiped everything down and ran the water again. Again, it was fine, but then it started backing up as before. I unscrewed the vent completely off and water came over the top completely.

So - what is the problem. We followed all the instructions as far as we know. Why isn't the vent venting properly? Do we not have it high up enough? How high does it need to be? This area is sort of vague - we get 4", 6" above the flood plane....

What is the solution to the problem?

Thanks for the help!!

If the water is backing up out of the pipe where the AAV is screwed in you have a stoppage in the sink line and it needs to be cleared. Also I would double check with your local codes about the AAV, lots of places do not allow them and some places do but you have to submit a letter and get approval from the local inspector.

We are working on the "clog" issue next, as it was also our next guess. Thanks for making us feel like we're headed in the right direction. As for code, we are in Michigan and they are okay (we have reviewed the plumbing code to ensure we're in compliance).

GalFriday said:

We are working on the "clog" issue next, as it was also our next guess. Thanks for making us feel like we're headed in the right direction. As for code, we are in Michigan and they are okay (we have reviewed the plumbing code to ensure we're in compliance).

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Thats good, was just checking due to the fact their are 12 states that do not approve the use of AAV's and 8 states that partial approve them with final approval from the inspector at the time of permit issue, and 2 cities that do not allow them NYC and Philly to name them.

AAVs are not looked upon very friendly by many professional plumbers. I think the main objection is that these are mechanical devices that can fail. For that reason, they should never be made inaccessible. In spite of the objections, these devices do work if install properly. There may be three problems causing your problems. The AAV may be defective, but that is no reason for joints to leak. If there is a clog, the water would not drain and back up, but the joints themselves should be water tight. The clog is the third problem you likely have and it may be the whole problem to begin with. I would suggest a professional plumber who has drain cleaning equipment auger the entire system. Please, do not use Draino or other caustic chemicals, they do not work on drain clogs in spite of the advertising hype.

Update to the issue,

We did use a chemical to clear any possible clogs and then ran the water. The odd thing is that when we're running water, it goes down just fine. When we fill the basin and then let the water drain, that's when there is backup at the AAV. Basically, when the water is running moderately, the AAV works fine, and there doesn't appear to be any backup issues. It's actually draining a lot better than initially (prior to us working on it; before it was SLOW). But, with a lot of water running down the pipes, it overflows at the point of the AAV.

One question we have is about the height of the valve. The instructions/documents/code all state it needs to be:

"located a minimum of 4 inches (102mm) above the horizontal branch drain or fixture drain being vented."

We need some clarification on this. 4" from the bottom of the AAV, from the top of the AAV, from the bottom of the drain, from the top of the drain?? Is height a major issue here? (We are sure we have it 4", but if we don't have it the "proper" four inches, maybe there is a problem.)

YOUR DRAIN IS PLUGGED

Forget about the AAV. The AAV is not the issue. The issue is a plugged drain. Don't put chemicals down it. They don't work and will only make the problem worse. Call someone with professional equipment to snake the drain out.

I have an old double sink and had similar problems. It had NO vent so I added an AAV. It soon stopped up completely. I soon found that the old galvanized drain pipes were clogged shut from rust. It took me 3 tries with a small hand operated snake to get it draining. Chemical openers will do nothing if you have a complete stoppage. I have now replaced all the galvanized piping with PVC. Here is some info about how to install an AAV on a sink.....double or single. My sink was working poorly for years and I always thought it was from the lack of a vent. That was not the case. I have removed another area of galvanized piping and it too was nearly closed up from rust and deterioration inside. Your problem is not a venting issue...it's a clog problem..

Atleast that link wasn't to hack work! Although I disagree on his take on plumbers putty.

kingsotall said:

Atleast that link wasn't to hack work! Although I disagree on his take on plumbers putty.

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I have seen some union shops around here use silocone to install the basket strainers as well. I too do not agree with this practice.

Silicone RTV makes basket strainer and pop-up assy. removal difficult at best...

that says it all

nhmaster said:

YOUR DRAIN IS PLUGGED

Forget about the AAV. The AAV is not the issue. The issue is a plugged drain. Don't put chemicals down it. They don't work and will only make the problem worse. Call someone with professional equipment to snake the drain out.

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I could have not said it any better.......

why would you worry about the AAV vent when both sides of the sink are stopped up to the top...

For Christs sake, stop trying to analyze the thing and just get the line rheemed out...
,

nhmaster said:

YOUR DRAIN IS PLUGGED

Forget about the AAV. The AAV is not the issue. The issue is a plugged drain. Don't put chemicals down it. They don't work and will only make the problem worse. Call someone with professional equipment to snake the drain out.

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WOW, I thought I was stressed!
What size of font is that yelling done in? Just so you know, people turn on their selective hearing in response, you got kids? lol.

AAV's suck but....
They never cause anything not to drain.
Clogged drains are the only thing that can cause that problem...

Well gee, thanks for the shout. We're not being imbeciles, we're actually trying to do this the right way. When we had the house inspected, the inspector said it was a clog. When I had a plumber come in (doing other major work) he said that the sink wasn't vented, and that was the problem. Thus, I assumed that the plumber would know more than the home inspector. My bad.

Today we will snake the drain and see what happens. It is only about 20 feet (if that) from the sink to the main outgoing drain, so we should be able to find a blockage easily. And yes, these are old galvanized pipes (1950 house) that were dormant for a while, so a rusted blockage is a distinct possibility. Thanks, Rich B. for your helpful reply.

That galvanized pipe is your problem GalFriday, I can just about guarantee it. If it's from 1950 it's in bad shape inside. If you have any 90 degree turns in it that will likely be where your stoppage is. I have a 2 family home built in the 50's. I removed the galvanized pipes from both kitchen drains and they were rusted very badly inside. Right where they enter the main 4" C.I. vertical stack was also closed up. I used a piece of rebar to rod out that area as well. My double sink used to back up regularly....one side filled up usually. I always used chemicals...it would open it up a little but eventually stopped up completely. A homeowner type snake is not very effective on this unless you really work on it for a while. I had a cleanout plug I was able to remove and then saw how bad the pipes were inside. You would be much better off if you just replaced the galvanized with pvc. My sinks drain like a water fall now!

I like shouting. It's good excersize and clears the sinuses.