Is this Air Admittance Valve Installed Correctly?

D107

This tiny half-bath sink was put in 16 years ago and it's never drained right. Drains slow, bubbles up at draining's end. Just replaced the old AAV and found much crud in valve and pipe leading to valve. But I noticed that while the height of the valve is more than 4 inches, it is still way below the bottom of the sink. Should I get an extender in there and get above the bottom of the sink? (The valve is straight up despite the photo appearance.)

Larry Weingarten

Hi, In an ideal world, the AAV would be above the flood rim of the sink. I'm imagining that the valve where it is, is often under some slight pressure, and may be sticking closed. Raising it up could only do good things, and likely keep the AAV cleaner. As the slow draining problem has existed since the start, how is the rest of the drain line? Any possible problems there? 🤔

Yours, Larry

D107

@Larry Weingarten It's quite good in most of the rest of the house—the basement slop sink sometimes gets slow but I just cleaned its AAV and now drains fine. I know the pictured sink's drain is quite small <2" so that doesn't help.

Larry Weingarten

Hi @D107, I'm a fan of AAVs. Used them in my home built over 20 years ago, and they are working fine. Still needed a main stack vent through the roof, but no other roof penetrations. I worried that the AAVs might leak, so put them as high as possible and above highest water line where I could. The height might be keeping junk from the valves. 😎

Not sure it's worth the effort, but you could remove the vent and extend the pipe up with some sort of hose. Then see if the sink drains any better…

Yours, Larry

ChrisJ

Does that sink have an overflow and what kind of drain is it. I.E. do you use a lever, or knob to close the drain, or is it one of the ones you push down on the top of the drain to close it?

Every bathroom sink I've seen that does not have an overflow drains horribly. The AAV is there to stop you from siphoning the trap out and is nothing more than a vacuum breaker. The AAV would never assist in draining.

D107

No overflow; no lever but a little strainer basket that you have to position just right for the rubber pieces on the bottom to stop the flow when you need to. As you can see from the video, it drains OK now with the new AAV which sits a little higher than the old one by a few inches. When I get time I intend to try to raise the AAV much more with the pieces I bought but for now this is ok.

Don't know if the zipped video will work, so I also attached photo.

Sink Ed.mov.zip

Intplm.

@D107

It looks ok. Take a look at these installation instructions.

This information can also be applied to the picture of the "Studor" vent you have pictured.

D107

@Inplm. Thanks, well the physics of why some AAVs may require placement above the flood level and others don't is beyond my knowledge. But my Studor placement seems most similar to the illustration on the right, except mine is much closer to the wall—much less straight pipe between vent and wall. The illustration on the left would seem to place the vent behind the wall which would require an access panel.

But this other V-200 illustration says it's to be used as a secondary venting means, that there must also be a main vent stack to the atmosphere. Perhaps if this vent was the primary and only venting means, it would THEN have to be above the flood level?

Larry Weingarten

Hi, It's a long shot, but could you get a photo of the sink drain with the strainer removed? I've seen slow drains caused by the washer there blocking flow some. 🤪
Yours, Larry

D107

@Larry Weingarten Don't think it's a washer—unless you mean the underside of the strainer in photo 2. But the overall size of the drain looks small—especially because of the built-in cross-strainer which surely cuts flow. Also could probably use a good cleaning to remove hair. Not sure if drano damages the plastic pipe.

MikeL_2

I suggest removing the aav and see if the sink drains differently without it. I'd put a pail underneath the tee just in case of an overflow

Larry Weingarten

Hi, Just under the crossbars of the sink drain, sometimes I've seen about half of that area blocked by the wrong washer. I don't see that problem with yours…. But you could test it by putting a bucket under the disconnected drain and see how fast the sink empties 🤔 Could get messy , or interesting 🙀

Yours, Larry

HomerJSmith

I don' know what type of soil piping you have in your house, ABS, PVC, Cast Iron, Copper, etc. You have to determine where the blockage is. If women use the sink, I have found on many occasions that hair balls build up before the trap and slow drainage.

pedmec

In my state there is nothing legal about that installation. Air admittance valves are not allowed unless with a variance from the plumbing board.

No slip joints after the trap.

D107

@MikeL_2 By disconnecting the AAV I assume you mean also covering that opening where the AAV was screwed in so I wouldn't get the sewer gas coming in.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1823257#Comment_1823257

What state is that? Citing code but not saying what code is confusing.

AAVs are legal in almost all states.

Your slip joint comment makes me think Massachusetts as trap adapters are also legal most places as well.

ChrisJ

No he means remove it and immediately test the sink to see if it helps. Plugging the connection wont allow it to vent outward like a normal thru the roof vent.

pedmec

yup Massachusetts. the bluest of the blue

pedmec

(d) Air Admittance Valves.1. Air Admittance Valves are not permitted, except with Special-permission from the Board.2. An individual vent, branch vent, wet vent, circuit vent, vent stack, or stack vent shall be permitted to terminate with a connection to an air admittance valve. Air admittance valves shall be installed in accordance with the manufacturer’s installation instructions.

10:16(D)

ethicalpaul

That's rather confusing. Sentence 1 says not permitted. Sentence 2 says shall be permitted and to do so in accordance with the manufacturer's instructions.