Bad AAV smell in my master bathroom? Help!

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John Howard

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I have lived in my double wide for about 5 years now. The first winter we went through in it, a horrible stench started coming from our master bathroom. I mean unbearably bad here. We searched and searched but could not find the source, so I we just assumed a rat crawled up into the insulation under the tub and died, so we would just have to wait the smell out. We sealed off the door to the master bath and ran the exhaust vent 24 hours a day. It took months, but it went away. The next year the smell came back with a vengeance. Again a futile effort was made to find the source, and again the bathroom was sealed off. Year after year, the same thing, but only in the winter.

I always thought the smell might be sewer gas, but having done some plumbing, I understood the pee-trap system to prevent sewer gas from getting into the house. I ran water in the sinks to make sure the pee-traps were full and checked the vents on the roof for blackage and all was well. But still the stench was there.

Each winter has been the same. But at long last I think I found the culprit. It is this thing. I have never seen this thing before and I don't know what it is, but it appears to be some kind of pressure relief valve that is letting the sewer gas into the house. This is a modern house that was built in 2010 and I don't understand how it could even be legal to install a device that would let sewer gas into a living space.

Can anyone tell me what this thing is and how it works, and why it lets sewer gas into the house Only in the winter time?

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Terry

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That is an AAV. It replaces the vent through the roof. It works on vacuum when the water pulls down the drain. I'm assuming you have at least one vent through the roof, which allows the use of AAV's for other locations. Is it possible that in Winter you have more wind, which can add pressure to the plumbing system as it goes past your roof vents. The AAV only works on negative pressures, not positive.
At any rate, the "cheater vent" you have is about the worst of the bunch. Oatey and Studor make some nice ones. I would at least switch that out.
My parents double wide on the farm had a bad AAV in their master. It was a pretty bad smell.

terry-mattawa-shovel.jpg


Mattawa, WA 1976
If you look the other way, you see the Columbia River. The other farm 10 miles to the East had a circle on it. This one was pretty bare.

oatey_aav_box.jpg


Oatey 39017 SURE-VENT AIR ADM VALVE, 1-1/2-Inch by 2-Inch, White
 
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John Howard

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Thanks a million. Let me ask you this. I screwed it down a few revolutions and the and the valve popped closed and stopped the smell. Is it okay to do this until I can order a better one?
 

John Howard

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It was easy to turn by hand, so it was not tight, but It did see the valve pop down when I tightened it up. The real mystery here is why this only happens in the winter time and never in the summer. I would love to hear an explanation for that.
 

Jadnashua

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The temperature underneath the cabinet may differ between seasons. Plastic pipe changes size quite a bit with temperature changes. Regardless, it should be tight enough to properly seal, and that threaded joint should have either a plastic pipe compatible pipe dope (not all pipe dope is safe on plastic pipe) on the threads or PTFE tape on them, otherwise, it does not create a proper seal, regardless of how tight you make it!
 

John Howard

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Thanks for the help. I don't see any sign of tape or goop sealant. Those builders just throw these mobile homes together as fast as they can. Mine was $96,000 new and it is built like junk. I'll never buy another.
 

Cacher_Chick

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There is nothing more than a thin piece of silicone rubber in there that acts as a flapper valve. The rubber degrades over time, and will eventually leak. Like Terry said, that particular brand was not good from the start.
 
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