Moved and replaced sink. Now slow draining

[beekeeper]

remodeling kitchen. Moved location and hence rebuilt drain under new sink. Now it drains very very slow. In fact, both basins begin to fill. Is there an obvious error in my new drain plumbing.

P trap is under right basin.
Drain from dishwasher air gap is in tailpiece branch below right basin.
Crown of Drain pipe into wall is 12" above cabinet bottom.
Bottom of pipe connecting basins is 11 7/8" above cabinet bottom.

I'd post a picture but I'm not sure how.

 

[beekeeper]

Here are the pictures. The last one is actually not as bad as it looks. The camera was tilted some and exaggerates the slope. Nonetheless, is does fall the wrong direction a bit.

 

[Sponsor]

 

[Reach4]

2) drain from trap to wall is flowing slightly in the wrong direction. It's slope is in-line with the drain pipe I connected to and I would think the elevation of the basin would overcome this slight fall in the wrong direction.

What does that mean? Are you saying that the pipe this drains into is similarly flowing uphill?

 

[beekeeper]

What does that mean? Are you saying that the pipe this drains into is similarly flowing uphill?

Yes. But that pipe is only a few inches long because it 90s (elbow) in the wall. So this entire run of "uphill" pipe is not even 12" long. I'll be a little surprised if that's the problem but only a little.

 

[Reach4]

1. That trap arm looks to be almost 12 inches long by itself although part of it is hidden. Only 12 inches total for the trap arm and the horizontal part inside of the wall?
2. With the level held level, what are dimensions A and B, or if you have an angle gauge

, what is the angle?

 

[beekeeper]

I'm not at home to measure it (I'll do that later) but I'd guess its a couple percent fall in the wrong direction. Carry that over approximately 12" total length and it would be a 1/4" fall in the wrong direction. If this is the problem then my thought is to cut it on the wall side of the coupling and replace that with an elbow so I could rotate that up slightly to get fall in the right direction between that and the trap. I would have to move the trap to the left basin to make this work but if it works I'm game.

 

[Reach4]

I'm not at home to measure it (I'll do that later) but I'd guess its a couple percent fall in the wrong direction.

I am going to guess 5%. Just a guess.

 

[hj]

None of that is the reason the sink does not drain. It is probably just a partial stoppage. How far did you move the sink and did you do any piping inside the wall?

 

[beekeeper]

We installed the new sink closer to the wall than the old. The old sink was at a 45 degree angle to the wall in a counter that jutted out into the room. I cut the old drain behind an existing elbow and pushed a cap on it while we did other kitchen work. With it capped nothing should have gotten into it. When we first observed the problem I removed the trap and pushed a plastic drain cleaner (long plastic barbed rod) through but it wouldn't go much further than the elbow in the wall before it stopped at the elbow (just didn't want to bend that way I assume).

But no. I did nothing to the pipe in the wall.

 

[beekeeper]

Reach4. The slope measures approx. 1/8" fall over 4.5" = 2.8%. The total length is approx. 10" from the trap to the elbow in the wall. At that length its only loosing 1/4" of the capacity leaving approx. 90% of the pipe's capacity.

 

[Reach4]

Your estimate was much closer than my guess.

I would probably try to figure out how to use a Brasscraft drain bladder to blow water in there. I would put a bucket under the opening to catch what spills out. It might not be such a good idea, since I might be forcing water up into the vent pipes. A drain bladder is nice if you can pressurize the pipe after any vent. I expect a real snake is the right way.

If you do get into the wall, you would probably want to add a cleanout at what is now the second elbow. Drain pipes often clog where they transition from vertical to horizontal.

 

[beekeeper]

hj,
After not using the sink all day and empting the trap (pipes should be completely empty) I ran the faucet on full and it took 25 to 30 seconds for it to fill to the sink strainer. After that the water level goes down very very slowly.

Considering this I'm inclined to agree with the idea of a clog. However, I'm still left wondering why it appeared now.

I can see the drain in the basement ceiling and count four 90s (including the one where the trap separates) and couple 45s. Would you recommend a snake considering all these bends or should I start with chemicals?

 

[beekeeper]

Reach4. No worries (about your estimate). The picture was tilted a bit making it deceiving. I don't like 2.8% in the wrong direction but I'll live with it if it works. That's the catch though isn't it? Getting it to drain. Ugh.

 

[Dj2]

Snake the line, fix the slope on the drain pipe, test with 3-4 full sinks of hot water and report back.

 

[Cacher_Chick]

Anytime there is not pitch in the correct direction, the solids will not be scoured out of the pipe and the result is eventually a restricted drain.

 

[beekeeper]

Bought a drum auger but it wouldn't go more than about 4 1/2 ft. Given the faucet flow, time it took to fill, etc. I figured the clog was about 8 ft in though. I felt it pass several elbows and would then not budge. After trying to pass that point several times I resorted to plan B. I poured 4 four rounds of three liters of boiling water down the drain. With each round flow improved until now it doesn't back up at all. I'm curious what the auger wouldn't pass and hope I didn't damage anything trying to get past it.

I can see about 3 ft or more of the drain so I may go ahead and remove another foot or so of basement ceiling so I can see what geometry might be preventing the auger from advancing.

 

[WorthFlorida]

It is possible that a blob of glue film over and partially blocked the pipe. The PVC glue can get hard enough that a hand auger could not push through it. After the relocation of the sink where is the vent pipe location from the sink?

To get the slope correct, if the drain pipes from the sink basins have bottom out into the fittings remove the the whole bottom setup and cut about 1/2 inch from each pipe and reassemble. That should pick up enough slope.