Air Admittance Valve Question

[MSattler]

Hi!

So my previous home had a AAV in the kitchen sink and I have experience replacing it.

My new home has a disposal, and a dishwasher that drains back into the main drain, and I will post a picture later tonight. Whenever the dishwasher runs, you can get the funky sewage smell. First thing I checked was to replace the AAV, but there is none.

I've got the AAV, but before installing it, does it matter where it installs in relation to the p-trap? I have a section of pipe between the sink and the disposal <Double sink> that has a nice long piece of 1 1/2" pipe where I could place the T, and put on the AAV.

Would that be ok, or is there a specific place it needs to go?

Thanks.
Marcus

 

[Reach4]

I've got the AAV, but before installing it, does it matter where it installs in relation to the p-trap?

Yes.

I have a section of pipe between the sink and the disposal <Double sink> that has a nice long piece of 1 1/2" pipe where I could place the T, and put on the AAV.

Would that be ok, or is there a specific place it needs to go?

It needs to be after the P-trap and on the horizontal that came out of the P-trap.

 

[Sponsor]

 

[MSattler]

 

[MSattler]

So when you say after the p-trap do you mean coming from the wall or going.to the wall?

In the pictures you can see the straight pipe where I wanted to put it.

Thanks!

 

[Reach4]

There is probably a proper vent in the wall. But I don't know why you have a smell. If there were to be an AAV in your picture, it would be at the wall. You would probably have to move things around to bring the P-trap farther from the wall. I am not a plumber, and I don't know how to track down your smell.

In your second picture, I see the disposal is not connected to its sink flange.

 

[Jadnashua]

A couple of things...a corrugated drain line from the DW has LOTS of places for food particles to get lodged, and they can smell rather nasty. That line should also have a high loop (go up to the bottom of the counter) before it comes down and into (probably?) the disposer...yours seems to be running fairly flat. A smooth-walled hose would be much better and would likely wash the inside better with each DW operation.

Adding an AAV to an already properly trapped and vented system buys you nothing. But, if you were to do it, you don't really have room without tearing up the wall and most of the existing plumbing...it needs to be after the p-trap (think the drainage path for after), and should rise up as high as you can go above the trap arm/fitting that goes down to the sewer. An AAV only lets air in, not out, and it's not clear that that is the reason for the smells you're experiencing.

 

[MSattler]

Hmmm ok, I'll look to get a replacement for the corrugated line. Not a big fan of the dishwasher anyways, wonder if it makes sense to just replace it since I have to pull it to replace the corrugated drain line, right?

What I don't get is why the smell only occurs when the dishwasher is running, and which is why I thought that there was a drain issue where perhaps the p-trap was going dry along the smell to come up. If the corrugated pipe has the smell, shouldn't it smell all the time? Or is the smell just from the dishwater running out of the corrugated drain line?

 

[MSattler]

Thanks everyone for your help!

So I went ahead and moved the dishwasher piping as suggested, and it seemed to have gotten better. Then of course the smell returned, but my gf and I noticed it actually seems to be coming from the living room AC vents. These vents are pretty close to the Furnace in the basement. There is a air return in that utility room, and one right outside the utility room.

So.... went into the Utility room, and checked the sump pump. The sump pump hole looks like it has 4 pipes in it, each coming from a different direction, under the concrete foundation. Is that a french drain, to help drain water before it causes damage to the foundation? I put plastic over the sump pump to make sure it's not smelling from there.

I dumped about 9 gallons of watcher/bleach into it, and ensured the pump works. The smell still persisted, although it only happens sometimes. I went and checked the sump pump and it still smelled like bleach.

I checked the condensation line for the A/C which drains into the sump pump. Is that normal? In my old house it went to an actual drain not a sump pump. The Condensation line does have a trap in it to block gases coming back up.

Next, I realized that there is a hookup for a washer/dryer in that utility room that is not used <use the 3rd floor w/d instead>. I went ahead and clogged up that drain pipe. So now I'm waiting to see if the smell comes back.



Anything else you guys can think of I could check?

I'm worried it may be a plugged vent line or a crack in a vent line in the utility room.

Is it time for a plumber and a smoke machine if it still comes back?