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msvatko · Feb 8, 2008, 02:11 PM

Hi, I'm remodeling my kitchen, and have a question about the vent tube. I have a sink in the center island, and want to make the entire counter flat. I currently have a backsplash behind the facet. When I removed the backsplash I found the vent tube going up higher than the counter surface, and then back down through the floor. Can I cut the vent tube so that it is lower than the counter top, and is there a spec height that the vent tube needs to be?

Thanks Mike

massplumber2008 · Feb 8, 2008, 03:21 PM

Hey Mike... the answer to your question will depend on what codes prevail in your area. Let me explain.

A vent needs to connect 6 inches higher than the flood level rim of the fixture it serves... this is for a few reasons... most importantly to keep waste from flowing down the vent should the drain clog. If vent tied lower than it should... say just as high as the bottom of your sink... your sink waste line could clog/backup and you would not know because it would just back up and run over/into and down vent... i.e. the vent would become the new waste line... that is a bad thing.

Anyway, you have two options: 1) You have an island vent that seems to connect higher than the flood level rim of the sink... that is good... except I then have to wonder if it runs under the floor and then back up the wall to tie into a vent stack (must tie in 6 inches higher than sink rim as mentioned)... or runs separately up into attic and ties into vent there... or at least somewhere above sink rim. See, an island sink vent should not be piped as you suggest yours has been. It should be piped similar to the attached picture below. IF yours looks like the picture and you can confirm that your vent under floor connects back up and into wall AND TIES IN HIGHER THAN FLOOD LEVEL OF SINK, then you can lower the vent under sink to look like the picture and you will be all set. If you cannot confirm that the vent connects higher than sink rim... then you cannot!

HOWEVER, if code permits in your area...you may be able to install a studor (AAV) vent as in the second picture...call inspector in town and ask him his opinion.

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msvatko · Feb 8, 2008, 08:19 PM

Originally Posted by msvatko

Hi, I'm remodeling my kitchen, and have a question about the vent tube. I have a sink in the center island, and want to make the entire counter flat. I currently have a backsplash behind the facet. When I removed the backsplash I found the vent tube going up higher than the counter surface, and then back down through the floor. Can I cut the vent tube so that it is lower than the counter top, and is there a spec height that the vent tube needs to be?

Thanks Mike

Hi, thanks for the information. If I cut the pipe and move it down 1 inch, then it will look exactly like the one in the picture. The current vent tube goes past the top of the sink. The house is 10 years old, and all the plumbing was professionally done, they just made this vent tube a little too high. Thanks again Mike.

iamgrowler · Feb 9, 2008, 07:04 AM

Originally Posted by msvatko

Hi, thanks for the information. If I cut the pipe and move it down 1 inch, then it will look exactly like the one in the picture. The current vent tube goes past the top of the sink. The house is 10 years old, and all the plumbing was professionally done, they just made this vent tube a little too high. Thanks again Mike.

The only real height requirement for the 'loop' section of a foot vent is that it be as high as possible in the cabinet base.

iamgrowler · Feb 9, 2008, 07:13 AM

Originally Posted by massplumber2008

Hey Mike....the answer to your question will depend on what codes prevail in your area. Let me explain.

That isn't a very accurate representation of a 'Foot-Vent', MassP.

The drain should be 2", the 1-1/2" San-Tee just below the floor should be a Combo and the C/O on the vent is placed incorrectly -- It should be on the vertical portion of the vent going up the wall.

massplumber2008 · Feb 9, 2008, 04:31 PM

Iamgrowler... I am afraid that my picture is as valid as yours. In fact, in Massachusetts I can pipe the "bow-vent" three different ways. Would you like me to get you drawings..

iamgrowler · Feb 9, 2008, 05:19 PM

Originally Posted by massplumber2008

Iamgrowler...I am afraid that my picture is as valid as yours. In fact, in Massachusetts I can pipe the "bow-vent" three different ways. Would you like me to get you drawings...?

You're allowed to run a kitchen sink drain in 1-1/2" and you're not required to have a clean-out on the vertical portion of the foot vent going up the wall?

As for the drawings, if they're handy, then I wouldn't mind taking a peek.

massplumber2008 · Feb 9, 2008, 05:25 PM

Cool... give me couple days.. glad to share (been awhile).

AND... I don't want to say no clean out in vent at wall in any or even all drawings... but just that they are each different... so is yours... but the cleanout... yeah that is a good idea. Talk soon.

iamgrowler · Feb 9, 2008, 05:53 PM

Originally Posted by massplumber2008

Cool...give me couple days..glad to share (been awhile).

AND...I don't want to say no clean out in vent at wall in any or even all drawings...but just that they are each different...so is yours.....but the cleanout...yeah that is a good idea. Talk soon.

I only ask because I worked on a few restoration projects in Worcester in the mid-80's and distinctly remember running all of the kitchen sink drains in 2".

Then again, that was twenty years and about 6 or 7 code revisions ago.

massplumber2008 · Feb 9, 2008, 05:58 PM

I promise to get back... love the feedback!

Beyhan · Feb 4, 2011, 04:08 PM

No! Do not cut that. It is the high vent loop that is required to vent the sink. That tube runs directly to your stack vent and without it your sink is going to start gurgling like crazy...

massplumber2008 · Feb 4, 2011, 04:25 PM

Hi Beyhan...

I'm afraid you are incorrect here... ;)

If you reread msvatko's question you will see that he is asking about an ISLAND SINK VENT and simply wants to cut the pipe down to the height just below the countertop. Since most island sink vents don't go higher than the counter as in his case, to lower the vent to the height of the countertop is more than acceptable... see images posted.

Also note the date of the post... Feb. 2008. Here's hoping that the work is completed by now, huh?

Good day!

Mark