Must Main Vent Stack attach vertically to Waste pipe?

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Elton Noway

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Wow... so many options, so many ideas. At this point after so many great solutions, unless there's an inherent concern with the concept I'm still leaning towards the vertical vent stack configuration per your design in post #27 appears. The only unknown (as far as implementing) is whether I plumb the tub using the partition wall as shown in #27 or go with the knee wall "variation" described in you most recent reply. Just to make sure I understand... in the recent reply, if I use the knee wall and bring the riser "through the floor" and eventually exit above the tub flood rim, I envision a vent loop per se. Correct... or am I confused? If correct... is there any problem with me then connecting the drain at the stack ?
kneevent.jpg
 

wwhitney

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Just to make sure I understand... in the recent reply, if I use the knee wall and bring the riser "through the floor" and eventually exit above the tub flood rim, I envision a vent loop per se. Correct... or am I confused?
I think you are confused, although I'm not sure I'm interpreting your marked up picture correctly. There is no loop of vents, although the vents plus the tub drain do form a loop.

As I understand it, the white PVC pipe with the black line and Xs through it is the old vent stack, and under the post #27 option, that gets relocated into the wall where we can see the back of the drywall. It also moves to be 2' from the wall with the pink insulation, rather than 4' from that wall. In which case from the perspective of the photo, it would end up about where the black line is drawn, if you think of that black line as being within the wall.

So with that in mind, I marked up your photo with just the dry vent lines between the floor and ceiling. The orange line is the 3" vent stack. The red line on the right is the dry vent coming over from the lavs, which are on the wall to the right of the picture (or maybe they would be at the edge of the picture, not sure). And the convoluted red line is the dry vent from the tub, coming through the floor in the knee wall, jogging into the lefthand exterior wall and then wrapping around to the wall with the vent stack. [For clarity, I show it rising in the lefthand exterior wall before wrapping around, but it could just keep wrapping around at the same height (well, sloped upwards at 1/4" per foot) as it exits the knee wall.]

Cheers, Wayne

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Elton Noway

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Oops... Sorry for the confusion. As mentioned earlier I liked your plan and vertical stack mentioned in post #27 but in that reply you included a comment "But the tub and the lav are too far from the 3" stack to be vented by it."

What I was attempting to ask (not very well sorry) was if I introduce a vent , (like the one you suggested with the red lines added to my drawing), would it alleviate the problem with the tub being too far from the stack?. In other words if I place vent connection somewhere in the knee wall, above the trap weir, and maintain the 1/4 slope... can I connect the tub drain back to the stack. It will probably be around 8 feet. FYI: Just wondering because the lav trap arm I removed during the demo was over 10 feet long. No inspections are involved... I just want to make sure the system will work properly. Thanks again!
 

wwhitney

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if I introduce a vent , (like the one you suggested with the red lines added to my drawing), would it alleviate the problem with the tub being too far from the stack?
Yes, if you run the drains below the floor as in post #27, and the vents above the floor as in post #42, all is copacetic.

Cheers, Wayne
 

Elton Noway

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I'm back... sorry :oops:
{snip}... I dont know where shower valve is going but lets keep that 3 or 4 inch stack clear of it .
Forgot a principle I learned years ago... P.P.P.P.P.P (Proper Planning Prevent Piss Poor Performance)
I remember reading Jeffs earlier warning but I was sure I could make it work. In the end the shower wall got jammed up fighting for real estate (stack, plumbing &mixing valve). I ended up relocating the stack location after all. It's new location is now directly over the main drain line thus offering the original vertical drop of the main stack (which negates my original question on connecting the 3" stack to the 4"main via a 45.)

I still have it stuck in my head I'd like to recreate a configuration similar to the vertical stack octopus (as shown in my OP) and use Waynes design from post #27 . However... after moving the stack location I'm also revisting Waynes #20 because it seems to lend itself to the location of the main drain (dotted blue line).
{snip...}
... if you aren't going to dry vent the tub, you have to went vent the tub, and the only option I see is to use the lav drains as is typical. That makes the lav drain take a circuitous route out of the area, but that's fine.
Cheers, Wayne
Below is Waynes #20... I just changed it to show the new location of the 3' vertical stack
new stack location2.jpg
 
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wwhitney

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FWIW, there's a few separate differences between #27 and #20:

(a) whether the tub is wet vented by the lav (requires the long lav drain run) or dry vented (requires a wall within 6' that can accept a dry vent)
(b) whether the WC is horizontally wet vented or is (possibly wet) vented at the stack.
(c) whether the shower is horizontally wet vented or is (possibly wet) vented at the stack.

You have a variety of options that will work, and it's basically your choice as to which way to go. You've only moved the stack 2', so I don't see it as that hard to modify #27 for the new stack location.

Cheers, Wayne
 

wwhitney

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You have a variety of options that will work, and it's basically your choice as to which way to go.
I didn't phrase this quite as explicitly as I intended, what I meant was that for each of the choices (a), (b), (c) you could make it independently of the other choices. So that's 8 different options right there.

Cheers, Wayne
 

Elton Noway

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I didn't phrase this quite as explicitly as I intended, what I meant was that for each of the choices (a), (b), (c) you could make it independently of the other choices. So that's 8 different options right there.

Cheers, Wayne
Not a problem... I followed your thought process perfectly. To make it easy on myself I'm leaning towards #27 which covers everything except where/how/if I'll eventually vent the tub. Still up in the air if I'll run a dry vent to the tub via the knee wall. Secretly... I'm kinda hoping if I dry fit everything running a drain straight from tub trap to the main stack I'll be able to squeak in at 8'. Right or wrong, my thought process is the old lav drain I removed was at least 10' and it passed. ( of course the code may have changed since it was installed back in 83.)
 

Jeff H Young

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Just a suggestion never think passing inspection has any thing to do with a job being done right or to code. I dont know how something was done before . many inspectors just sign the card they might be a combo inspector that knows nothing about plumbing they might overlook something an honest mistake , or they might see something that they know isnt legal but just dont want to make a big deal out of it. people say all the time "it passed inspection" also the oposite happens a inspector fails work that complys honest mistake but happens then you have plumbers that think something is illegal because they failed something that was actually done right . In a nut shell copying existing work dosent mean its right or ever was.
 
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