Kitchen Island Sink Vent

[MicEd69]

I'd like to get some comments on four venting options for a kitchen island sink. There is a hollow column adjacent to the island where a vent from the basement sink goes up to connect to the vent stack in the attic.

The sketch below marked as Original Plan has a vent from the island sink P-trap directly connecting to the vent line from the basement. It connects to the vent line below the flood line of the sink, but should the drain line plug, the water would simply back up and flow down the vent line. This seems to me to be an acceptable design, although perhaps not to code.



In my jurisdiction, I can use an AAV, although I really don't like those when there is a batter alternative.



Then there is the classic loop vent.



And then I thought with the vent line right there, I could connect the vent side of the loop vent to the vent line from the basement.



I'm still favoring the Original Plan. I have a great relationship with the city inspector as a Professional Engineer and have provided him a lot of information on various unique design issues. He respects my opinion and I believe he will allow me to install what I feel is the best approach, per code or not.

But I thought I would through this out there for comments and recommendations from you professional plumbers.

The loop lines would be 2" if I used that design, and all the straight vent lines are 1 1/2".

So, what do you think and thanks in advance for your comments.

 

[Twowaxhack]

I’d go with plan #1 and add test tee cleanouts on both vertical pipes so you can clean both directions. It’s less work than plan #3 and is still serviceable.

Plan #2 would be easy but you would eventually have that AAV go bad. No big deal typically.

#3 is common but a lot of codes want a real vent within 15’, often called a foot vent. They also want a cleanout innthe foot vent.

#4- nope.

With the choices given, The I’d pick #1 or #2, but I’m not considering what’s code or not, just what works. #3 would also work. #4 would work but I’d never pipe that, no need.

 

[MicEd69]

I’d go with plan #1 and add test tee cleanouts on both vertical pipes so you can clean both directions. It’s less work than plan #3 and is still serviceable.

Plan #2 would be easy but you would eventually have that AAV go bad. No big deal typically.

#3 is common but a lot of codes want a real vent within 15’, often called a foot vent. They also want a cleanout innthe foot vent.

#4- nope.

With the choices given, The I’d pick #1 or #2, but I’m not considering what’s code or not, just what works. #3 would also work. #4 would work but I’d never pipe that, no need.

Thanks Twowaxhack!!! Adding those test tee cleanouts will be easy.

The horizontal line between the vent from the sink and the vent to the vent stack will be fitting to fitting, so it will only be a few inches. But would you think it better to use a wye for that connection like below?

I'm going to go ahead and ask this question because I already modified the sketch. But I am going to state that I hate engineers who "over engineer" installations. In other words, that's what it appears I'm doing here.

Comments?

 

[Twowaxhack]

Either way, just add the test tees on each pipe.

 

[breplum]

You describe a peninsula, not an island plumbing.
UPC allows vent below flood rim of the fixture when "drainage fittings are used (long sweep 90s) so just tie in to the available vent stack and you are done. No need to do anything more.
It is good practice to have a 2" cleanout right inside the sink cabinet under or above the tee

 

[MicEd69]

You describe a peninsula, not an island plumbing.
UPC allows vent below flood rim of the fixture when "drainage fittings are used (long sweep 90s) so just tie in to the available vent stack and you are done. No need to do anything more.
It is good practice to have a 2" cleanout right inside the sink cabinet under or above the tee

Yes, you are correct, it is more of a peninsula rather than an island in the plumbing sense. It's just adjacent to a hollow column and not a wall, so it looks more like an island.

Thanks breplum!!!

 

[MrInfoPhilly]

If yo go with Plan 1., best., run the vent section 6 inches above flood level rim and tie in with a Wye fitting.
Technically you 1_1/2" vent should be upsized to 2 inches.
I don't like AAV's unless absolutely needed.

 

[MicEd69]

If yo go with Plan 1., best., run the vent section 6 inches above flood level rim and tie in with a Wye fitting.
Technically you 1_1/2" vent should be upsized to 2 inches.
I don't like AAV's unless absolutely needed.

I cannot run the vent section 6 inches above the flood level as that will place the vent line 6 inches above the countertop of the peninsula. And why would a vent need to be 2 inches when it is only venting a single P-trap? It is not a wet vent. And I don't like AAVs either as I stated above.

 

[MrInfoPhilly]

I cannot run the vent section 6 inches above the flood level as that will place the vent line 6 inches above the countertop of the peninsula. And why would a vent need to be 2 inches when it is only venting a single P-trap? It is not a wet vent. And I don't like AAVs either as I stated above.

Your picture shows the 1.5 in vent stack connected to the tub correct?
1.5 inch vent holds 2 fixture units
1.5 inch serves 8 fixture units.,

Also your picture showed the wall with 1.5 inch, i went off that as far as going 6 inches above.

 

[MicEd69]

Your picture shows the 1.5 in vent stack connected to the tub correct?
1.5 inch vent holds 2 fixture units

Also tour picture showed the wall with 1.5 inch, i went off that as far as going 6inches above.

Oops, I forgot about the tub was vented through that line as this was a few months ago.

However, a 1 1/2" vent is good for 8 DFUs not just 2.

The sink is too far from the hollow column to keep the vent at a 45-degree maximum until it gets 6" above flood rim.

 

[MrInfoPhilly]

Oops, I forgot about the tub was vented through that line as this was a few months ago.

However, a 1 1/2" vent is good for 8 DFUs not just 2.

The sink is too far from the hollow column to keep the vent at a 45-degree maximum until it gets 6" above flood rim.

Correct., 8 for the vent... I was thinking of the drain units... Been up since 4am... No excuse though.... Run the vent however., i was just saying if limited space for the tie in., you can run the 2 pipes next to each other on the vertical SECTION and have the wye for the tie in and 45 it into the vent stack.

Get there from the column above 6inches however needed.

 

[MrInfoPhilly]

You describe a peninsula, not an island plumbing.
UPC allows vent below flood rim of the fixture when "drainage fittings are used (long sweep 90s) so just tie in to the available vent stack and you are done. No need to do anything more.
It is good practice to have a 2" cleanout right inside the sink cabinet under or above the tee

what do you mean buy upc allows vent below the flood level rim?
Section 905.3 says unless prohibited by structural conditions., must be 6inches above the flood level rim.
So what am I missing? maybe something new or something I'm missing

 

[esso72]

You describe a peninsula, not an island plumbing.
UPC allows vent below flood rim of the fixture when "drainage fittings are used (long sweep 90s) so just tie in to the available vent stack and you are done. No need to do anything more.
It is good practice to have a 2" cleanout right inside the sink cabinet under or above the tee

Hi - I found this post and I have a similar problem. In my house I have a peninsula and only 1 drain pipe was install in the middle where the kitchen sink will be. The half wall is about 32in, and the nearest wall is about 5' before I can start turn vertical. taking that into account I only have about 28" in order to slope the vent pipe and come out into the wall around 32".

From your comments looks like UPC allows it, but my county uses IPC 2018, would this be the same?
DO I have to used 2" pipe for the vent?
Not sure if I will put a clean out since it feels that I dont have a lot of space for 2" SanTee, 2" Clean out and 2" Long sweep elbow
Do you recommend a AAV, instead?

Thanks in advanced

 

[MrInfoPhilly]

Hi - I found this post and I have a similar problem. In my house I have a peninsula and only 1 drain pipe was install in the middle where the kitchen sink will be. The half wall is about 32in, and the nearest wall is about 5' before I can start turn vertical. taking that into account I only have about 28" in order to slope the vent pipe and come out into the wall around 32".

From your comments looks like UPC allows it, but my county uses IPC 2018, would this be the same?
DO I have to used 2" pipe for the vent?
Not sure if I will put a clean out since it feels that I dont have a lot of space for 2" SanTee, 2" Clean out and 2" Long sweep elbow
Do you recommend a AAV, instead?

Thanks in advanced

View attachment 44533

If you're that close to the wall, Why not add a vent? You can use a 1.5 inch pipe for the vent.
But if you are that close to the wall, why can't you install the Sanitary tee in the wall and go straight down to the drain?

 

[esso72]

If you're that close to the wall, Why not add a vent? You can use a 1.5 inch pipe for the vent.
But if you are that close to the wall, why can't you install the Sanitary tee in the wall and go straight down to the drain?

Concrete is already pour and we put the drain in the middle of the sink. I am not interested in cutting if I can avoided
I see what you mean

 

[Twowaxhack]

I’d most likely use an AAV at this point.

I’d for sure install a cleanout.