Slow kitchen sink

[ll1542]

I have a single sink that is running slow. When I first turn the water on it immediately backs up into the sink then will start to move a bit. I have clean out in the back of the cabinet that I opened and this seemed to help the situation. So I added an AAV back there and it did not work as well. Also, I noticed when I disconnected the dishwasher line the water went right down. I will try to add a couple of pictures to show my set up. I do not think its a clog because I can run the sink with the cleanout open and it never over flows even though there is water in the sink. I replaced everything from the sink to the main drain line.

 

[WorthFlorida]

is this a new problem or always has this issue?

AAV's only allow the air to enter from a slight vacuum when water drains. I think your problem is an air dam. When you disconnected the DW drain, it allowed to air to escape. Roof vents allows air to go in both direction.

What the fix is I have no idea. It all looks normal. With the AAV removed and
with an open pipe, does it still drain slowly or immediately. If you run the water slowly, does the problem still happen?

Scum and food waste love to stick to the inside walls of the pipe. Have you removed the trap and checked the tailpiece?

The DW drain hose should be looped higher than the tail piece. This will allow the last foot or two to drain and leave air inside the drain hose.

 

[Sponsor]

 

[Reach4]

Let's look at the less likely one first. One explanation would be that your drain line has a belly before it joins other well-vented lines. If the only problem was a vent problem, expect the drain to drain fine.

I tried to illustrate this in https://terrylove.com/forums/index....alves-exist-like-air-admittance-valves.95874/ #4

Now for the more probable: Another real way this could happen is if there is too much surface tension right at the drain basket. See if thrusting a soda straw thru one of the holes in the drain basket to make sure there is not a pressure developing right below the basket. The straw lets air into there. This sometimes happens with disposals, and the cure is to nibble some of the rubber from the flaps to let some air in. In a basket, I guess enlarging the slots a tad could be the cure.

 

[Jeff H Young]

a belly sounds like a possibility

 

[ll1542]

Thanks everyone for your inputs. So this drain has always been a slow drainer. It is hit or miss, this morning drained really slow now it is pretty good. I did try the straw and it helped a little, I am wondering if they sell drains with larger holes in them or is it possible to have a 2" sink connection instead of an 1.5"? Also, I took a picture of the vent line and it does not appear to have a belly but wondering if a clogged vent would cause that? I had to rebuild the part right under the sink due to a leak but everything down there seems sloped correctly. It did completely clog and I ran an air bladder in it which unclogged it and got it flowing but still not like my other drains. Also wondering if I put a tee right below the sink and put the aav there, kind of like a two sink set up if that may help. Thank you for all your inputs I am attaching a photo of the vent line. It is about 3 feet down from the elbow in the floor joist.

 

[WorthFlorida]

An AAV will not help. You need to get the air out of the tail piece. Have you tried any of the suggestion from my last post?

What would work is add an air gap drain for the DW. This will allow air to escape into the room. You would need to install it through the counter top. The drain side would still go to the tail piece.

Kraus Dishwasher Air Gap in Spot Free all-Brite Stainless Steel KAG-1SFS​

 

[ll1542]

Hi, Thank you for the help. I will have to try and set up this air gap. I was hoping to avoid that. I did try your suggestions. I left the pipe open and if when the sink is run at full tilt it backs up. So last time it did that I stuck the straw in there and it burped and went down and cleared. So I think it is air backing up in the pipe by the dishwasher tube. Thank you for all your help I really appreciate your time and expertise!