Kitchen Sink -- disposal hookup, drain miscalculation

RemodelBob · Jun 3, 2008

When I roughed in my kitchen, I placed my 2" drain stub out where I thought would be close to the edge of the cabinet making it easy to install my p-trap and disposal.

As it turns out, the wife wants the disposal on the left side, which is just about right in front of my stub out. If I moved it to the right basin it would be a no brainer, but I would never be able to change it up.

So I am going to rig it to fit in the left side.

Here is what I have, let me know if this is legit or crazy.

2" stub out
2" 90 (short on the horizontal--wrong I know, but well oversized--just not enough room for a long sweep)
2"-1.5" bushing
1.5" Y to street 45 to disposal p-trap
1.5" Y to street 45 to right basin p-trap
1.5" 90 to stub to studor vent (AAV)

The pictures are of the problem and the un-glued setup. The san-t you see with pipe is just there to hold it up. I am going to strap it to the back wall as cleanly as possible.

Let me know what you think...in the meantime I will be chipping away at the leftover plywood the counter buys left in the way of my faucet hookups...

hj · Jun 4, 2008

drain

Of all the possible ways you could do it, and we would have to be there to determine the best one, you have chosen the worst. It would never pass ANY inspection, and will have many functional problems if you do it that way. Your first mistake may have been using 2" pipe.

Sponsor · 2022-01-29T12:20:58-0800

Redwood · Jun 4, 2008

It looks like you are working way to hard to hook up a drain. It looks pretty though.

I'd hook up the faucet before I put all that stuff in the way...

Jimbo · Jun 4, 2008

Have you confirmed that AAV is allowed? Most places, the fact that it may be difficult to get to a real vent does not mean it is impossible, and the inspectors do not allow it.

Sjsmithjr · Jun 4, 2008

Assuming the AAV is allowed, are you allowed to come of the horizontal like that? Also, does anyone allow for two traps on one arm like that?

-Sam

Gary Swart · Jun 4, 2008

Apart from the arrangement of the pipes, it appears you are mixing PVC and ABS pipe.

RemodelBob · Jun 4, 2008

jimbo said:
Have you confirmed that AAV is allowed? Most places, the fact that it may be difficult to get to a real vent does not mean it is impossible, and the inspectors do not allow it.

AAVs are allowed--it is a little tough to put a vent line in after the sheetrock and cabinets are installed.

RemodelBob · Jun 4, 2008

Gary Swart said:
Apart from the arrangement of the pipes, it appears you are mixing PVC and ABS pipe.

The ABS is to be glued together and the PVC is your standard slip coupling p-trap setup. They are mechanically fastened, so it is fine.

RemodelBob · Jun 4, 2008

hj said:
Of all the possible ways you could do it, and we would have to be there to determine the best one, you have chosen the worst. It would never pass ANY inspection, and will have many functional problems if you do it that way. Your first mistake may have been using 2" pipe.

HJ, how would you hook it up? This was my mock up and I was looking for advice because I didn't like how complicated it came out.

I could have simplified down to one Y and have both sinks share one p-trap, but those dual sink diverters look to constrict the flow a lot.

Terry · Jun 4, 2008

You should have the vent before the p-trap, if you use an AAV, then it would be on a fitting before the trap. In the drawing above, the pipe going up is the vent,
With an AAV, the pipe would be cut shorter, and the AAV installed. (with access for air and replacement)

RemodelBob · Jun 4, 2008

when you say "before the p-trap" do you mean between the p-trap and the wall?

I think that is what I have. I just put the AAV off to the far right because I wanted to get it as high as possible (with room to remove and replace if needed).

I would hook it up just like your drawing, but the drain stub out is directly behind the disposal, which is why I am here looking for layout advice.

Thanks
Rob

Sjsmithjr · Jun 4, 2008

remodelbob said:
I think that is what I have. I just put the AAV off to the far right because I wanted to get it as high as possible (with room to remove and replace if needed).

Right now you have vent, trap, trap, drain. You want trap, vent, drain.

Like HJ said, using 2" pipe in the cabinet isn't helping matters.

What is the dimension between the disposer housing and the back of the cabinet?

Is the dishwasher to the left or right of the sink?

-Sam

RemodelBob · Jun 4, 2008

What is the problem with 2"? Everything I have read says that oversize pipe is better. Some places have even said that oversized pipe can eliminate the need for a vent. Since there was no practical way install a vent, I opted for oversize pipe and an AAV. I could understand smaller pipe being a problem, but why would larger pipe be a problem?

I don't have an exact measurement right now, but the 2" 90 is about 1" away from disposal housing. My guess is a 2" 90 is about 4". So I am guessing 5" from the back of the cabinet.

Dishwasher is to left of cabinet.

So what you are saying is pull the vent off the Y on the left and use one of those constricting double sink hookups into one p-trap and dump that somewhere further to the right?

Terry · Jun 4, 2008

Maybe this picture will help you see where the vents belong.

hj · Jun 4, 2008

drains

You have been reading the wrong materials. Because of flow velocities and self scouring properties, larger drain lines are not always better. But in your case 2" does not give any advantages and takes up more space. The problem with your mock up is that both drains connect to "S" traps, and the AAV does absolutely nothing to improve them. I might place an elbow behind the disposer, then a 1/8 or 1/16 elbow facing towards the right hand sink. Then use a conventional disposer/continuous waste configuration with the trap connecting to the drain pipe, after installing a 2x1 1/2 reducer and then a trap connector.

RemodelBob · Jun 4, 2008

hj said:
You have been reading the wrong materials. Because of flow velocities and self scouring properties, larger drain lines are not always better. But in your case 2" does not give any advantages and takes up more space. The problem with your mock up is that both drains connect to "S" traps, and the AAV does absolutely nothing to improve them. I might place an elbow behind the disposer, then a 1/8 or 1/16 elbow facing towards the right hand sink. Then use a conventional disposer/continuous waste configuration with the trap connecting to the drain pipe, after installing a 2x1 1/2 reducer and then a trap connector.

Thank you. I will mock that up tonight.

RemodelBob · Jun 4, 2008

based on your feedback I came up with this mockup. let me know what you think.

2" 90
2" - 1.5" bushing
1.5" section of pipe
1.5" Y off to AAV
1.5" 90 to trap adapter (currently have a street 90, but thinking about using a long sweep)

The first picture shows what the ABS looks like.

The second shows the pvc slip joint p-trap setup.

I am not in love with that diverter, but if that is the way to do it, then so be it.

Thanks

RemodelBob · Jun 4, 2008

and here is the clearance behind the disposal with the 2" 90.

hj · Jun 5, 2008

drain

Scrap the disposer's outlet elbow. You should have gotten a disposer kit continuous waste with a straight flanged tailpiece, (instead of the elbow one you have which is to connect two sinks with strainers rather than one of them being a disposer), which connects directly to the disposer and goes directly to the tee, rather than making two 90s before going horizontal.

Sjsmithjr · Jun 5, 2008

No need to call a plumber, as soon as he looses that elbow coming off the disposer he'll have it licked.

-Sam

Kitchen Sink -- disposal hookup, drain miscalculation

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