Any disadvantages to using an AAV

[Al S]

I have a plumber at the house who originally suggested that an AAV, properly installed will adequately vent my kitchen sink.

I need the 1 1/2 inch galvanized vent pipe that goes through the roof removed as it is installed into the living space by way of the 45 deg fitting and not going through the plate. I asked that the galvanized vent pipe be removed. Now he's saying an AAV may gurgle when a sink is full of water as it's a one-way air valve.

Can someone please clarify this?

 

[Reach4]

I don't know how you would get gurgling due to an AAV, unless there was a second problem.

Note that under a kitchen drain is a prime place for a clog, especially where the drain pipe switches from vertical to horizontal. In your work, I suggest you add a good place to rod that line in the case of a future blockage.

Disadvantages to AAVs is that they can fail. I don't know if they are silent, but I don't expect a resulting gurgle. But yes, the AAV is a one way valve. So I think he claims that as you open the stopper of a full sink, air will have to get out of the way. But if the drain line is not blocked, air can push down the drain line.

 

[Sponsor]

 

[Terry]

An AAV only works with negative pressure, no positive pressures. A vent through the roof does both. In fact a vent through the roof is needed somewhere in the system for an AAV to function correctly.
In the Seattle area, when we have an Island Sink, it's common now to use an AAV. They work fine, mainly because the rest of the home is well vented through the roof.

If a trap gurgles, that would be an indication that the trap is being siphoned and not properly vented.

 

[Al S]

An AAV only works with negative pressure, no positive pressures. A vent through the roof does both. In fact a vent through the roof is needed somewhere in the system for an AAV to function correctly.
In the Seattle area, when we have an Island Sink, it's common now to use an AAV. They work fine, mainly because the rest of the home is well vented through the roof.

If a trap gurgles, that would be an indication that the trap is being siphoned and not properly vented.

Sorry, Terry. I forgot to mention that there is a main stack on the roof for that serves rest of the house. It looks like a 5 or 6 inch pipe through the roof. That serves the upstairs and downstairs bath toilets, sinks. I wanted to use the AAV for the kitchen sink only.

So given that, is there any reason why I cannot utilize the AAV?

 

[Al S]

I don't know how you would get gurgling due to an AAV, unless there was a second problem.

Note that under a kitchen drain is a prime place for a clog, especially where the drain pipe switches from vertical to horizontal. In your work, I suggest you add a good place to rod that line in the case of a future blockage.

Disadvantages to AAVs is that they can fail. I don't know if they are silent, but I don't expect a resulting gurgle. But yes, the AAV is a one way valve. So I think he claims that as you open the stopper of a full sink, air will have to get out of the way. But if the drain line is not blocked, air can push down the drain line.

I don't know how either. The statement was made that due to the fact the AAV was a one-way valve that it can gurgle due to the amount of water that could be in the sink. The AAV has a 160 DFU (Branch), 24 DFU (Stack) into a 2 inch PVC pipe.

Now I'm no plumber to be sure. I researched the crap out of this. I considered hiring a plumber because I couldn't find an appropriate donut for the cast iron hub that the current galvanized waste line goes into. And here we are.

 

[Reach4]

A sink with an S-trap (no vent at all) will drain very nicely. The problem is that it can drain so well that the U of the trap empties out, and gasses can come in.

 

[WorthFlorida]

My home, built in 2007, has four AAV's and 1 roof vent near the clothes washer. It's is also the same side the main waste line exits the home. Zero issues with drainage and no gurgling. One AAV for each bath vents two full bathrooms, one for the 1/2 bath, one for the island sink.

 

[Jeff H Young]

I believe a vent through roof is better , costs more for material, cost more for labor extra roof penetrations mean more chances for leak. Disadvantage of AAV something mechanical to fail and its not a vent nor equivalent to a vent through roof, but argument is do you really need it? as George stated his Florida home functions fine with 4 AAV installed.
I still like a real vent but there is no reason to believe you'll have gurgling I suppose its possible the AAV could make a noise especially if defective but not the end of the world to replace it .