Drain/vent for new basement sink

[homeowner_bob]

Hi forum. Thanks in advance. I'm adding a basement wet bar and would like to use an existing 2" drain/vent line from our kitchen sink upstairs. The picture I captioned is pretty clear (I think!), but i'll type it out too. I'll be re-routing the existing 2" drain line straight down, then horizontal to where the basement sink drain taps into it. It will continue horizontal to the main stack. The new basement sink wye would obviously be horizontal too.... I just can't show that in the picture.

I believe everything is to-code in terms of fixture units, sizes, wye/sanitary T, etc. I know it doesn't matter code wise - but as a wet bar this will get minimal usage compared to a kitchen/lav sink.

Any issues with vent location (connecting to drain before/after wye)? Height? Size?
Are my Wye/Sanitary T's correct?
Anything else stick out or that i'm missing?

 

[Sbude57]

I would eliminate the vent off the bar sink and just use an AAV. The way your kitchen sink is vented would not be allowed here. You could use a 2"x 1-1/2" TY for your bar sink.

 

[Sponsor]

 

[Tuttles Revenge]

Without getting into the kitchen drain not having a long sweep on that fitting dropping from the ceiling to the horizontal run that's getting replaced and its odd venting under the flood level with connections that aren't drainage. I'll have to research MD code when I have a spare moment... but not right now.

The bar sink needs to be plumbed with the drain as shown in blue, but with a San Tee on the vertical for the sink trap arm to vent separately from the sink drain above. They need to be independent of each other. IE.. the sink above can't drain through the vent of the sink below.

Also.. getting back to the vent from the sink above. Since the height of the vent for the sink above is Below the Flood level of the sink its serving, you can not connect another fixture to that vent until a point of 6" above the flood level. The reason is if that drain from the upstairs sink were to clog, the waste would fill up the vent then start dumping down the vent of the bar sink and you would never know that your drain was clogged.

 

[John Gayewski]

If you could start your 3x2 sanitary tee, with the bottom of the tee on the floor you could run your piping along that wall sloping up to the new kitchen sink with a wye and st 45 looking straight up, then continue sloping up to catch the kitchen sink.

Going back to the new sink since you'd have a wye looking straight up you could then install a 2"x1.5"x1.5" sanitary tee for the new sink drain at the desired height. The top of the sanitary tee would be your new vent that should be vertical until you get above your new bar sink. Then it can turn horizontal to tie into a dry vent somewhere or go straight up through the roof (or an aav if they are legal in your area and your inclined to use one).

 

[homeowner_bob]

Thanks all. The explanation of the upstairs sink clogging and it dumping down the vent made sense. The current vent setup will not work.

AAVs are allowed for us, with inspector approval, but even with that I don't like them in principle. I need to find a way to route the vent another way so it can connect above flood level.

Tuttles: good call on the long sweep. I will use one on that new long drop vertical to horizontal.