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Author:
sdub (WA)
I'm having a strange issue with (I think) my air admittance valve under my kitchen sink. A very common problem, but I don't know how to fix it or what else to look for.
At first I thought my double sink in the kitchen was clogged. I've snaked up to 25 feet, it's all clear. And then with the sinks full of water (and blocked, not draining), I unscrewed the air admittance valve (6 DFU) just enough to let a little air pass through.
Immediately the water drained, like a miracle.
To my (novice) knowledge, it would seem that the issue is with the air admittance valve - maybe a bad spring or something. So I replaced it, and the issue remains the same. Could it be that I need an AAV with a higher DFU value?
If there is no clog, and the sink drains just fine with the air admittance valve partially unscrewed, what could be the problem?
Thanks!
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Author:
steve (CA)
There is a clog/belly in the pipe. A pocket of air is getting trapped between the clog/belly and the sink, keeping the water from flowing. Removing the AAV lets the air out of the pipe, so the water can get in.
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Author:
hj (AZ)
Th e "problem" is that the drain IS CLOGGED. Since the AAV only lets air in, the air trapped between the clog and the sink blocks the drainage until you remove it and let the air out.
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Author:
m & m (MD)
If you remove the AAV and run the faucet for an extended time, you will probably flood water out the open pipe eventually.
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Author:
Lucie (Canada)
I have the same issue. I have brand new pipes and sink(new kitchen) and new mechanical air vent (air admittance valve) which was all installed by a plumber. Ever since it was installed, the sink drains really slowly and eventually, water even goes up the other sink (I have a double sink)- I changed the AAV for a new one thinking that it was defective but the problem remains.
Note that if I remove the AAV the water drains normally. I tried unscrewing it a little, just enough so the water would drain but I noticed today that there is a leak and water seems to go up the pipe where the AAV is and leaks out from there.
Any idea what the problem could be and I can solve it? The plumber say that his installation is fine...
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