8/3/15

The house I moved into has the setup below (at the tinypic url at the bottom of this post) under the sink.

I have noticed that it is nearly impossible to get the garbage disposal side to drain properly and I am thinking it has to do with the 2 traps that are installed.

From my research (youtube videos and forums) it appears that 2 traps is a no-no in almost all cases. Additionally, I came across some information about venting, but I am unsure if my setup has, or requires, a vent. (there is a pipe running from the wall that has a black cover on it, but this does not appear to be a vent...maybe it was intended to be a vent, but it was never properly finished...or maybe someone thought they knew what they were doing and removed the vent there?).

I *think* what I need to do is:
1. Eliminate the trap connected to the disposal.
2. Run the disposal drain over to a new 'T' that would go below the tail-piece from the left sink (between the tail piece and the trap).
3. Run a new pipe from the single trap to the drain in the wall.
4. *maybe* replace the black cover with a vent?

Any help would be greatly appreciated!

[tinypic.com]



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The studor vent needs to be at least 4" above the trap. You have a 3" pipe stubbed up for the drains, that's a good thing. You could stack two tees , the lower for the disposal and the top for the left side of the sink and add a studor vent atop the tee's.
You could also use an end waste as you said. I don't think a lack of a vent is the cause of the slow drainage, it's probably partially clogged in the branch of that wye.

as a test, remove that rubber cap and try the drain.
other than a venting issue, that set up is fine.
you don't want two traps in series trap. but side by side is OK.

The two traps are not a problem, but the lack of a vent is. Without a "proper vent" a stoppage almost anywhere in the system will prevent either sink from draining, or at least draining properly. If the disposer is not draining properly,the problem is probably in the disposer, not the drain lines.

Thanks all!

The drain only seems slow on the disposal side, so I guess I will start taking things apart and seeing if there is a clog.

My plan of attack is disposal trap, then the black cap, then the disposal last, I don't really want to take that apart!

Any other advice is welcome, thanks for your time!

Andrew



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Ideally you want a 2 part waste where the garbage disposal dumps into a tee, the branch of the tee picks up the other side of the sink and the bottom of the tee enters into the trap. When you run the disposal, if forces water through the tee and flushes the trap clean. Beware of Rhubarb in a disposal, it can stop up an 1 1/2" line quickly and you have to take the line apart and dig out the strands of fiber.

The black cap has NOTHING to do with it, and you do not want to take the disposer apart. DEpending on how old it is, the cutter plate and surrounding ring may be corroded so the openings are closing off. If that is the case you need a new disposer.

quote; Ideally you want a 2 part waste where the garbage disposal dumps into a tee, the branch of the tee picks up the other side of the sink and the bottom of the tee enters into the trap. W

That is the COMMON way of doing it, but it is not necessarily the 'ideal' way to do it. Two traps are actually better but they are more time and expense to install them. (In fact, I have a 3 bowl sink and it has THREE traps under it.)



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