Fitting at soil pipe(with diagrams now)

[wwhitney]

AFAIK, wet venting is not allowed to mix with kitchen drainage.

That's true for horizontal wet venting, but if he's using san-tees and the trap arms aren't too long, the only wet venting is vertical through the lavatory drain. I don't think there's a restriction to bathroom groups for vertical wet venting.

Cheers, Wayne

 

[wwhitney]

I can't do it exactly like that, the toilet would need need to be on the lower san tee as well for slope

Ah, the issue is that the tub drain can run between floor joists, while the toilet drain has to be lower to cross under the joists?

Cheers, Wayne

 

[Sponsor]

 

[wwhitney]

I don't think there's a restriction to bathroom groups for vertical wet venting.

Interestingly, the UPC doesn't mention bathroom groups in the section on vertical wet venting, while the IPC does.

https://up.codes/viewer/connecticut/ipc-2015/chapter/9/vents#912.1.1

However, as I read that section, the restriction is on which fixtures can rely on the vertical wet vent as their vent. It doesn't restrict discharging other fixtures into the vertical wet vent. This contrasts with the section on horizontal wet venting, which says "Any additional fixtures shall discharge downstream of the horizontal wet vent."

So I don't see any IPC problem with the triple san-tee. The only issue would be rodding and whether and where a cleanout would be required.

Cheers, Wayne

 

[Coolwhip]

You want to vent the shower and toilet. Is this going to happen in fact with your proposal? Logic says yes. Is this going to be considered proper venting under IPC? I tend to think not, but I am not sure. AFAIK, wet venting is not allowed to mix with kitchen drainage.

That was the problem I was trying to fix.

Will the AAV between the lavs not serve the tub? If not, I'll just put an AAV after the tub trap, I had planned to do this in the first place but then for some reason I got the idea in my head that the AAV at the double fixture tee between the lavs would be all that is needed.

Does the toilet really need its own vent on top of the soil vent pipe? I don't know about the UPC, and not that I've seen a lot, but I've never seen an additional vent for the toilet here, only the sink drain/SVP acting as vents. And I think functionally the AAV would serve the toilet as well if more venting was needed.

Can someone with more certainty tell me if I really need an additional AAV for the tub to satisfy the IPC?(and toilet I guess) Putting another after the trap for the tub isn't a big deal, but I'd rather leave the toilet alone.

Ah, the issue is that the tub drain can run between floor joists, while the toilet drain has to be lower to cross under the joists?

Yes.

So how far in plan is it from the (a) the toilet flange and (b) the bathtub overflow pipe to the soil pipe? Even better would be coordinates for all three points in plan.

Well, not exactly sure how to give directions here....but if you were standing in front of the lavatories(double) and looking at them represented NORTH, remembering that the soil pipe is almost directly below the sink on the right, the bathtub drain is almost directly 3 feet to the EAST of the soil pipe, not south or north at all really.....the toilet flange would be 8 feet 200 degrees south-southwest from the soil pipe.

As far as all that fitting mess, besides the concern about stacking two san-tees on top of each other, I just didn't know if a different configuration of fittings could solve the (at the time not known/understood to me) problem reach4 was concerned about....as far as stacking goes, its really a game of mm at that point, a quarter inch difference and precisely where the apexes occur could be the difference between fitting and not fitting, although I guess I could notch the joists though I'd rather not damage them at the edges....appears moot not anyways.

------------------------

It looks like we are pretty much settled as far as the fitting goes(at least I am, unless someone else chimes in and says reach4 is right and whitney is wrong), I will use the triple san-tee. I appreciate the help very much, the only worry left in my mind is whether I need another AAV after the tub trap?

But, in case the above scenario occurs....is the drain the occurs after the AAV really considered a wet vent if the valve only serves fixtures behind it? Like I know in my set up its a wet vent for the tub...but its not a wet vent for the sinks, so if I put an AAV on the tub, would it still be a wet vent for the tub since now the tub has its own vent? Or is it a wet vent for the toilet? And the SVP is not considered the toilet vent but the sinks are?....Even then, the kitchen drain never really shares any pipe with the wet vent...

It looks like it would work fine either way, I would like everything to be up to code and definitely wouldn't want any egregious ones, but I'm fine with ambiguous ones as long as they work.

Thank both of you very much(and you as well Jeff).

 

[wwhitney]

Will the AAV between the lavs not serve the tub? If not, I'll just put an AAV after the tub trap, I had planned to do this in the first place but then for some reason I got the idea in my head that the AAV at the double fixture tee between the lavs would be all that is needed.

The AAV for the double lav, where is it going to be? Will it be at least 6" above the lav rim? It needs to be accessible.

Does the toilet really need its own vent on top of the soil vent pipe?

As you mention, once the toilet drain hits the san-tee, it is going to be vented by that san-tee. So it makes sense to me to design it that way, regardless of what other possible toilet venting may be downstream.

as far as stacking goes, its really a game of mm at that point, a quarter inch difference and precisely where the apexes occur could be the difference between fitting and not fitting

If you are trying to keep everything as low as possible, your build-up from the soil pipe would be: Shielded Coupling, 3" length of 3" pipe, 3x3x3x2 san-tee with side inlet, 3x2 bushing, 2" street san-tee. Per the Charlotte catalog, if 0" is the elevation of the top of the soil pipe, then you'd have these elevations:

Top of rubber separator in shielded coupling @ 1/8"
Top of 3" pipe segment @ 3-1/8"
CL of toilet inlet @ 6-1/4"
CL of kitchen inlet @ 6-7/8"
CL of tub inlet @ 11-1/8"

Cheers, Wayne

 

[Reach4]

The AAV for the double lav, where is it going to be? Will it be at least 6" above the lav rim?

Care to cite what makes you think that 6 inches is required? Makers don't say that.

It needs to be accessible.

Yes.

 

[wwhitney]

Care to cite what makes you think that 6 inches is required?

I'm not very familiar with AAVs, so I was reading IPC Section 918 on them. https://up.codes/viewer/georgia/ipc-2018/chapter/9/vents#918

That section talks about branch vs stack AAVs, there are two different listing requirements for the two types. And it talks about branch AAVs being installed on a horizontal drain, while stack AAVs serve a stack. The branch AAVs are required to be 4" above the horizontal drain, while the stack AAVs are required to be 6" above the highest flood rim level of the fixtures served.

So what's unclear to me is whether installing an AAV on a vertical vent pipe coming out of a san-tee automatically means it is a stack AAV and has to meet those requirements, or if the OP's AAV is still considered a branch AAV.

Cheers, Wayne

 

[Reach4]

That section talks about branch vs stack AAVs, there are two different listing requirements for the two types. And it talks about branch AAVs being installed on a horizontal drain, while stack AAVs serve a stack. The branch AAVs are required to be 4" above the horizontal drain, while the stack AAVs are required to be 6" above the highest flood rim level of the fixtures served.

So what's unclear to me is whether installing an AAV on a vertical vent pipe coming out of a san-tee automatically means it is a stack AAV and has to meet those requirements, or if the OP's AAV is still considered a branch AAV.

https://webstore.ansi.org/preview-pages/ASSE-Sanitary/preview_ANSI+ASSE+1050-2009.pdf says

Stack Air Admittance Valves (AAVs) for Sanitary Drainage Systems (herein referred to as “device”) are devices used in plumbing drainage systems to prevent the siphonage of water trap seals. These devices do not relieve back pressure; they only allow air to enter the system. These devices are designed to be installed on stacks where branches on multiple floors are connected.
​

So I don't think that an AAV serving a double fixture fitting or a sanitary tee would be considered a stack AAV.

In the link you provided, this section could be clearer I think.

918.3.1 Horizontal Branches

Individual and branch-type air admittance valves shall vent only fixtures that are on the same floor level and connect to a horizontal branch drain. Where the horizontal branch is located more than four branch intervals from the top of the stack, the horizontal branch shall be provided with a relief vent that shall connect to a vent stack or stack vent, or extend outdoors to the open air. The relief vent shall connect to the horizontal branch drain between the stack and the most downstream fixture drain connected to the horizontal branch drain. The relief vent shall be sized in accordance with Section 906.2 and installed in accordance with Section 905. The relief vent shall be permitted to serve as the vent for other fixtures.

918.3.2 Stack

Stack-type air admittance valves shall be prohibited from serving as the vent terminal for vent stacks or stack vents that serve drainage stacks having more than six branch intervals.​

 

[wwhitney]

Thanks for the clarification, I agree with you. I need to remember that "stack" refers to a vertical drain pipe that is more than one story.

But the language on branch type AAVs doesn't really seem to contemplate multiple fixtures served by horizontal drains at different heights. I guess the inference is that it has to be 4" above the highest horizontal drain served. So that would be 4" above the lav double san-tee in the OP's case.

I think that we can now say with confidence that for the IPC, an AAV for 6 DFUs or greater for the lavs would properly vent the tub and toilet, as long as their trap arm/fixture drains are not too long: 8' for 2" drain, 12' for 3" drain. [I had thought the IPC had an unlimited length for the toilet vent, but I couldn't find that, so either I missed it, or it was changed, or I was mistaken.]

Cheers, Wayne

 

[Reach4]

But the language on branch type AAVs doesn't really seem to contemplate multiple fixtures served by horizontal drains at different heights. I guess the inference is that it has to be 4" above the highest horizontal drain served. So that would be 4" above the lav double san-tee in the OP's case.

I think it needs to be 4 inches above the trap arm. If you combine, such as venting two santees with 1 aav, then 6 inch above flood level for the combining.

 

[wwhitney]

I think it needs to be 4 inches above the trap arm. If you combine, such as venting two santees with 1 aav, then 6 inch above flood level for the combining.

"flood level for the combing"?

I thought we agreed that an AAV venting the double lav, and vertically wet venting the bathtub and toilet, would still be a branch type AAV, so it would only need to be 4" above the highest horizontal branch (the lavatory trap arm).

Cheers, Wayne

 

[Reach4]

"flood level for the combing"?

I thought we agreed that an AAV venting the double lav, and vertically wet venting the bathtub and toilet, would still be a branch type AAV, so it would only need to be 4" above the highest horizontal branch (the lavatory trap arm).

With two separate santees, we need to combine the vents. With a double fixture fitting, only one vent.

 

[wwhitney]

Right, but does combining the vents imply a stack AAV, or is it still a branch AAV? I would say it is still a branch AAV if the fixtures are all on the same story and there's no stack.

Cheers, Wayne

 

[Reach4]

Right, but does combining the vents imply a stack AAV, or is it still a branch AAV? I would say it is still a branch AAV if the fixtures are all on the same story and there's no stack.

I agree with your interpretation. The term "stack AAV" was new to me until you used it.

 

[Jeff H Young]

yes you need a cleanout for your 4 inch to water closet ( meaning a minimum 3.5 inch not a 2 inch at the lavs which is why i suggested coming thru floor with a bigger pipe). kitchen sink also needs a cleanout. been a bit busy to keep up good luck with it!