Sink drain correct and to code?

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Dave12345

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This drain (picture attached) does not drain efficiently. Looking at it I think it should have a Sanitary Tee instead of a Wye (in red rectangle) and that the drain isn't supposed to go from 2 inch to 1 1/2 inch (also in red rectangle). The vertical pipe (blue rectangle) is a vent; there is a bathroom sink connected (green rectangle) below the vent and the horizontal pipe leads to a bar sink (green circle). Should this be draining OK and separately is it likely code compliant?
 

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wwhitney

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That picture is very wrong, although I'm not convinced that at the bottom of the red rectangle you have a 2" pipe draining into a 1-1/2" pipe (which would be very very wrong). I think that may just be one of those hub to pipe rubber couplings, so you have a 1-1/2" plastic hub joined to the stub of 1-1/2" coming out of the floor. Did you actually confirm that the barrel of the wye (away from the hubs) is 2.3" OD, while the OD of the drain below is 1.9" OD? That's Schedule 40 2" and 1.5", respectviely.

Anyway the problems that should be fixed:

- Unshielded rubber couplings can't be used above grade, so they need to be replace with shielded rubber couplings.
- The trap arm from the sink at the green circle to the stack needs to fall at most one trap diameter, so 1-1/2". Meaning the distance from trap to stack is limited to 6' at most if you get the perfect minimum 1/4" per foot fall, you can't have any downward jogs, and you need to hit a san-tee at the stack. This is probably why your bar sink doesn't drain well. If the bar sink trap is more than 6' from the stack, you can revent the bar sink (ask if what that means isn't clear).
- If the vent above and the drain below are both 1-1/2", and I'm wrong and you do have 2" plastic in between, that doesn't work and the 2" needs to be replaced with 1-1/2" (adequate for a bar sink and a lavatory)
- If the lavatory is wet venting any fixtures in the bathroom (common, although you haven't provided any info on the bathroom), then you're not allowed to connect a non-bathroom fixture there, and the bar sink drain should be rerouted to join downstream of the bathroom fixtures. Plus even if were so allowed, the common drain of the bar sink and the lav would be required to be 2" to act as a wet vent, and you see to imply the drain at the very bottom is 1-1/2". However, as fixing this would be a huge hassle (requiring breaking open the floor), and it is not likely to be a problem in practice, you could let this one slide.

Cheers, Wayne
 

Dave12345

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Thanks Wayne,
Much appreciated. You are confirming my concerns about the wye and the 2 to 1 1/2 coupling (its definitely 1 1/2 on both sides of the PVC though it isnt obvious in the pic.) I wasn't thinking about the fact that they are unshielded and when I take this out I will correct that.

I don't understand this part: - The trap arm from the sink at the green circle to the stack needs to fall at most one trap diameter, so 1-1/2". Meaning the distance from trap to stack is limited to 6' at most if you get the perfect minimum 1/4" per foot fall, you can't have any downward jogs, and you need to hit a san-tee at the stack. This is probably why your bar sink doesn't drain well. If the bar sink trap is more than 6' from the stack, you can revent the bar sink (ask if what that means isn't clear).

Here is what I think I understand:
-Max distance on a 1 1/2 inch p-trap is 6 feet
-Over 6 feet get an auto-vent
-max 1/4 ft fall
-No downward jogs

Thanks again,
Dave
 

wwhitney

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-Max distance on a 1 1/2 inch p-trap is 6 feet
Yes, for the IPC.
-Over 6 feet get an auto-vent
Not sure what you mean by auto-vent. The simplest way to deal with over 6 feet is to use a horizontal combo (or the IPC would allow a san-tee on it back) to take the dry vent off within the distance limit, and then have the dry vent rise to at least 6" above the fixture flood rims, and then turn horizontal and continue above the horizontal drain to join the stack in the portion of the stack that is a dry vent.
-max 1/4 ft fall
That's minimum 1/4" per foot fall. Given the 1-1/2" total fall limit, to maximize the horizontal distance between trap and vent, you have to minimize the fall rate. And a 1/4" per foot fall rate is the minimum allowed. (1/4" / foot) * 6 feet = 1-1/2".
-No downward jogs
Well, you could do a smaller downward jog between the trap and the vent takeoff if you needed to for some reason, but it counts against your maximum 1-1/2" fall.

Cheers, Wayne
 

James Henry

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You need to cut that mess out and install a santee on the stack, the drain needs to run horizontal the whole way. What ever the horizontal jog needs to be, they make 22-1/2 degree fittings. If that doesn't work then you can install an AVV anywhere along the drain. The last thing that always fools people into believing they have a slow drain are the 1" diameter strainers with the tiny drainage holes in them, they cannot drain fast enough for the amount of water that is running in the sink.
 
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