Wide window & not close to a vent

**magnadyne** · 07-03-2011, 09:03 AM

Hello all of you plumbing pros. This site has helped me many times in the past, but now I have a unique situation I have to post about.

I am remodeling my kitchen and moving the sink to an exterior wall, centering it under a 78" wide window. (The 78" is from the outside of the studs on either side of the window)

My problem is that I am having trouble figuring out the best way to vent the sink. I plan to use 2" drain line so if I am looking at code correctly my vent can be up to 4ft away (correct?)
However, the main vent for the house is about 10ft away (where the sink used to be) and on an adjacent wall.

My initial plan was to run a vent next to the window down through the floor where it can meet up with the drain from the sink.

I will be within my 4ft, but it will be towards the edge of it. Is there a better way to do this that I am not thinking of?

I have looked into AAV's, but there seems to be mixed feelings on this. Even when it comes to code, so it makes me wonder if this would be the best way.

Your thoughts....

Thanks in advance for any help!

**jadnashua** · 07-03-2011, 09:15 AM

A vent can't go down from its initial connection...otherwise, it would get clogged with crud, water, waste, and not provide the venting function - it needs to be a sloped path to open air to work. You might be a candidate for use of an island vent scheme (search here for how to do that). An AAV might have problems if you have a garbage disposal...AAV's let air in, not out, and a GD can act like a pump and pressurize the line...this needs to go somewhere, and an AAV won't (or at least shouldn't) let anything out.

**cacher_chick** · 07-03-2011, 09:16 AM

The trap arm will need to run to a drain and vent stack which runs vertically on the side of the window. Once the vent stack is in the attic, you can run it horizontally (with pitch) to connect to an existing vent through the roof or to a suitable location to run it through the roof on it's own.

hj · 07-03-2011, 09:28 AM

From your description, I get the impression you have absolutely no idea about venting. The 4' is from the trap to the vent and after that it does not make any difference how far it has to run. If you the pipe "down through the floor" it will NOT be vent, or any possibly anything else other than a pipe through the floor.

**magnadyne** · 07-03-2011, 02:26 PM

Sorry, I did not describe my plan well enough. Cacher_chick has the right idea with what I was thinking in that the vent (being a vent and not a drain) will go vertically up to the attic where I can then span the 10ft needed to meet the main drain.

So, to try an be more specific, and to make sure everyone is on the same page...
I am planning on a 2 bowl sink with one side having a garbage disposal and there will also be a dishwasher next to that. I then plan to have the usual traps under the sink and drain through the floor. Oncce past the floor joists in the basement the drain will follow the exterior wall. From the trap under the sink using 2" pipe I have up to 4ft to connect to a vent stack. I plan to do this by connecting to my vent stack in the basement and running it vertically up through the exterior wall, and into the attic. (Where I can then go as far as I want with slope to vent exiting the home. Since my window is so wide I must put the vent stack right after my window.

My concern with this is the fact I am coming close to maxing the 4ft limit. If the experienced people here have done this without having issues I will continue down this path and sleep well at night. However, if having the trap near the 4ft mark on a kitchen sink with disposal and DW is not advised, I will look for alternatives.

Jadnashua,
Thanks for the tip on the AAV with a disposal! That pretty much puts the nail in coffin for that idea, and I can focus on more conventional methods. I have looked into island venting as well, but I have read that island vents are only allowed for islands and not to code when installed in a place where the fixture is attached to a wall that reaches the ceiling.

Thanks again. I hope this clears some things up.

**LLigetfa** · 07-03-2011, 02:43 PM

Originally Posted by magnadyne

I then plan to have the usual traps under the sink and drain through the floor...

That would result in an unvented S trap.

**magnadyne** · 07-04-2011, 06:23 AM

Originally Posted by LLigetfa

That would result in an unvented S trap.

Thanks! I knew something didn't seem right about my idea.
I will see what I can do to run the drain through the wall to meet up with the vent.

Thanks again!

hj · 07-04-2011, 08:47 AM

quote; From the trap under the sink using 2" pipe I have up to 4ft to connect to a vent stack. I plan to do this by connecting to my vent stack in the basement and running it vertically up through the exterior wall, and into the attic.

That is what I meant when I said you have no concept of venting. The vent CANNOT connect in the basement if the trap is under the sink.

**cacher_chick** · 07-04-2011, 03:32 PM

Normally the trap arm would be routed across the inside of the backs of the cabinets at proper pitch until it turns into the drain and vent stack in the wall.