Rerouting a plumbing air vent pipe

We're taking down a section of the wall between our kitchen and living room and we want to drop the 'bar height' down level with the sink. Unfortunately, the bulk of the section we're removing has plumbing and electrical in it. Most of that is not an issue. However, I'm trying to determine if I can reroute the air vent for the plumbing as below. The closest I could find on how to do it would be with an 'island loop':


I'm trying to determine if I can reroute the vent as such, rerouting in blue, existing sink level in red line:



As far as I can tell, the relevant bit of the georgia plumbing code is this, but I'm trying to determine what exactly has to be 6" above the sink?:

what is going on under he floor of the kitchen? I see 3'' stubbed up and a Cross, are their 2 drains ?

your assumption is correct on the method of venting for an island.

BUT with out knowing what/how the 3'' is installed now.[underfloor] I can not give you an answer that what you want to do will work.

I would like more info.

Its a concrete slab and the 3inch pipe is the only waste down through there. The right side of the T has been cut off and nothing goes there. I don't know why it was there but there is nothing connected to the right side of the T.

A friend just suggested I don't need the loop at all, that I can simply reroute off the to side.

there is an old school island vent that will work.

see the bad drawing

So you're suggesting not venting to the outside at all? Just the air inside the 3in pipe?

yes, your pipe is oversized. use the top as a vent, combination waste and vent

a vents main job is to keep equal atmospheric pressure in the plumbing system so that your trap does not get back syphoned. or sucked dry. your pipe being over sized will accomplish that job

I've never saw one like that before Frodo. Interesting! I can see how it would work for an 1 1/2" drain, but I have a feeling it's not up to any code

It is the way I prefer to vent island kitchens if I can. It satisfies International Plumbing Code requirements.

The only change I make is to install a 3" test/cleanout tee underneath the tee for the drainage, as I like to have an access for a full size cutter head should the line ever require snaking.

I learned that lil trick in Florida. I had been running the foot vent. till i saw how to upsize the kitchen drain line.

never ran a foot vent again'

it is actually called a combination waste and vent.

and to be total legal, needs a vent run off the line to the nearest wall

My code book is still at my old place, but I'm gonna look into that when I get it back!

section 910.5 says no vertical drain pipe, so does that mean what you're suggesting is in violation of that code?

see apendix B, it says for use on Fd Or Fs, but with permission from Inspector, In orlando, we use it on island sinks

I do not know about IPC..

Orlando would be IPC. Although in '94 when I started, it was under Standard Plumbing Code.

Just checked 2010 Florida plumbing code, the only vertical part is the connection from the fixture drain to the horizontal combination drain and vent pipe. It can serve floor drains, sinks, lavatories, and drinking fountains. You can't run a disposal drain through it.

i was in orlando in 84 do not know what code it was under. worked for midstate plbg


a 3'' island vent at that time was common practice