Gurgling Sink After Remodel

[JasonG]

I have a gurgling sink after a remodel project.

The old setup was a large cement sink in the basement where the washing machine emptied into. This sink had no vent pipe or visable trap, but it worked fine. The drain pipe went right into the cement slab. I assume after this point the drain pipe connects to the main waste pipe which connects to the city sewer.

We replaced this sink and I added a trap and an AAV. We also remodeled the kitchen directly above it and moved the kitchen sink which now drains into the same drain pipe. I added an AAV to this sink as well.

Now, when the washing machine empties into the basement sink, the kitchen sink gurgles a bit.

[nhmaster]

That's the AAV doing it's thing. Another reason to love them

[Master Plumber 101]

Your Air admittance valve is not installed correctly. It should be either off the horizontal portion of drain before it goes to the 90, or vertical end of a tee min. 4" above trap. That's if it is installed as you have drawn up.

Also check to see if the aav you installed is code approved. My state only allow's Studor vent's to be installed and that will not be for long because of problem's the device is currently having.

[JasonG]

Sorry about the bad drawing... AAV is actually installed like in this picture. It is well above the 4" minimum and is probably close to 18" above the trap on both sinks. They are both Studor vents, and Studor vents are approved for use in my area.

Yeah, I probably should have vented it differently than using AAV's and I still might do that to correct the problem.

But... I want to understand why this is happening first. Do you think there is something below the concrete preventing the air from going down and out the main vent?

[Ian Gills]

I had a similar problem when I replaced my concrete sink that WAS properly vented. It turns out that the pipe the utility sink drains into was a little gunky.

After cleaning the pipe out (I used lots of liquid plumber ) the utility sink empties quicker and the gurgling has gone too.

[Grimace]

The old setup was a large cement sink in the basement where the washing machine emptied into. This sink had no vent pipe or visable trap, but it worked fine. The drain pipe went right into the cement slab. I assume after this point the drain pipe connects to the main waste pipe which connects to the city sewer.

If it didnt have a trap then wouldnt this sink have vented sewer gas into the basement?

[JasonG]

If it didnt have a trap then wouldnt this sink have vented sewer gas into the basement?

You would think so, but that didn't ever seem to be a problem. As I was working on the drain pipes throughout the house, I had several of them wide open, some for extended periods of time, and never smelled any sewer gas ever.

[Gary Swart]

I have had a similar experience. I attributed it to the fact the the city sewer main is at least 60 feet away. I don't know if that is a valid conclusion, but for whatever reason, I had no sewer gas that I could detect. I did keep a rag in the pipe anyway.

[MACPLUMB 777]

You Have A Partial Blockage And Need To Snake Drain To Clear
And The Noise Will Stop

[cwhyu2]

A lot of old laundry trays with no visable trap drained into 3" traps under
the floor and considered floor drains either direct or indrectley connected.

[jadnashua]

It's my understanding that you must have a path to the air on any line where an AAV is used if it isn't the only thing. The AAV only lets air in, not out. Depending on where you are, the vent may need to let air out, and there has to be a path for it. I'm not sure you have that. Or, I might be all wet!