Back to Back Toilets: Double Fixture vs Double Wye

[wwhitney]

Well, the difference I see between the vertical reducer and the reducing closet elbow is that the reducing closet elbow doesn't have any flat or projecting internal surfaces that could catch waste. While the reducer has that 1/2" rim around the inside, which is hopefully slightly sloped but still could catch waste.

Beyond that, I don't really know as I don't have the experience. Perhaps someone else will comment. I also don't really know how much of a priority to assign step (2.5). Obviously step (1) has to come before step (3), but (2.5) could happen anytime, and maybe (1) and (3) are more important.

Cheers, Wayne

 

[Jeff H Young]

kinda late here , but my biggest thing I see is that heel outlet on back I'd eliminate any way possible. and of course the double santee. but even if you can't quite meet code . pic in post 60 looks close but like I said the 2 inch needs come off a wye ditch the H.O.L 90!

 

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[wwhitney]

kinda late here , but my biggest thing i see is that heeloutlet on back id eliminate any way possible. and of cource the double santee.

Yes, that's in the works. What would you say about the short 4" WC riser up in the joists that reduces to 3" via a 3x4 reducer?

Cheers, Wayne

 

[SoConfused]

Wayne, I see what you're saying about the lip on the vertical reducer potentially being an issue. I'll look at the extra one I have next time I'm down there and see how much slope their is.
Hi Jeff, thanks for joining the discussion. As Wayne said, I'm definitely getting rid of the heel outlet. I too would be interested in your take on my vertical 4x3 reducer instead of a closet bend. I sure don't want to redo that section again if I don't have to. I'm not as concerned with code as I am function.

 

[Jeff H Young]

not crazy about the reducer and doesn't meet code a bit of a technicality as a reducing 90 is allowed, but a reducing 90 is solidly proven to function very well.
If you leave the reducer its not any more work to fix it later , I could understand you don't want to pull the toilet . I think there is a chance of buildup at the reducer not sure it will or not (be an issue)

 

[SoConfused]

Thanks Jeff. I'm inclined to leave it for now. I'll rethink the reducer for the other WC when I get rid of the double santee and the heel outlet. I appreciate your input!

 

[SoConfused]

Well, the difference I see between the vertical reducer and the reducing closet elbow is that the reducing closet elbow doesn't have any flat or projecting internal surfaces that could catch waste. While the reducer has that 1/2" rim around the inside, which is hopefully slightly sloped but still could catch waste.

Beyond that, I don't really know as I don't have the experience. Perhaps someone else will comment. I also don't really know how much of a priority to assign step (2.5). Obviously step (1) has to come before step (3), but (2.5) could happen anytime, and maybe (1) and (3) are more important.

Cheers, Wayne

Hi Wayne - I'm getting ready to do step 1 of moving the 2 inch pipe to join the 3 inch drain downstream of the toilets. I think I'm pretty clear on that part. (I'll only do step 2.5 if it becomes a problem. That reducer has a good slope from the 4 to the 3 and right below the toilets there should be plenty of force to wash solids down it.)
As for step 3, that's not quite as straightforward. I held a SanTee and long sweep elbow up where the 4 way is right now and I don't have enough height to make that work. So my question is - on Terry's drawing in post #30 it looks like both WCs are wet vented rather than the left WC being wet vented through the right WC, which is dry vented. Is it acceptable to have the two WCs BOTH wet vented to the same vent?

If that's not a problem then I'll just hook straight from the vent to a combo like he shows then connect the right WC to the drain line like I did the left one, with the exception that I'll cap the end of the combo with a cleanout fitting. I'm attaching the current set up from 2 different angles.

As always - I appreciate any input you or anyone else cares to share!

 

[wwhitney]

As for step 3, that's not quite as straightforward. I held a SanTee and long sweep elbow up where the 4 way is right now and I don't have enough height to make that work.

I won't have a chance to look at the rest of your question until later today, but on this point:

- Is that with a street san-tee and regular LT90 (or street LT90 and regular san-tee), or with two all-hub fittings? Because the street version should be 1.5" shorter than having touching hubs.

- If the upper horizontal segment (3" WC fixture drain) and lower segment (current 2" line going into the 3" line) were directly on top of each other (not skewed), then another option for the vent takeoff and the drop in elevation would be to use street 45 - wye with the barrel at the 45 degree angle off plumb and the branch vertical for the vent - (possibly street) 45. [That's only an option for a WC vent takeoff, other traps need to be vented before the trap arm starts downward like that.] If the misalignment between the upper and lower horizontal segments is not too great, you might be able to make that configuration work, not sure.

- Once the 2" is out of the way (if you start your jog before you get close to the earlier WC above), you have the option to cut the 4" drop from the WC, extend it downward to a lower 3x4 reducing closet bend, point that at an angle so that a short pipe and a horizontal 45 (or maybe 22.5) will let you get in line with the existing lower 3", and then use an upright combo (or san-tee on its back if you need something more compact, since you are under the IPC) to connect up to the existing vent above.

Cheers, Wayne

 

[Jeff H Young]

personally don't like the HOL 90 at all would have a regular 90 there and a wye just downstream picking up the 2 inch even with a few more 45s . but you seem capable if you want to try it out ok, but not the kind of way I like to see it. thanks for showing us and sharing this problem

 

[wwhitney]

So my question is - on Terry's drawing in post #30 it looks like both WCs are wet vented rather than the left WC being wet vented through the right WC, which is dry vented. Is it acceptable to have the two WCs BOTH wet vented to the same vent?

The drawing in #30 is fine. It is dry venting the right WC and wet venting the left WC.

The difference is this: every fixture has a trap (or outlet for the WC), then some drain that is unvented, and then a vent connection. For the right WC, the the vent connection would be that combo in the middle, and the vent has only air, so that's a dry vent. For the left WC, the vent connection is at the wye, and the vent is horizontal up towards the combo, then vertically up. The horizontal portion between the wye and combo carries the right WC's drainage as well as the left WC's vent, so that's a wet vent.

If that's not a problem then I'll just hook straight from the vent to a combo like he shows then connect the right WC to the drain line like I did the left one, with the exception that I'll cap the end of the combo with a cleanout fitting. I'm attaching the current set up from 2 different angles.

That would be fine, although it's not quite like the other WC, as there you started vertical, then 45, then combo (if I recall), but the outlet of the combo for the vent would be horizontal. If you're willing to cut the 4" pipe from the right WC and extend it, you can basically do the above but dropped down to the lower horizontal drain level, as I suggested in my earlier post today.

Cheers, Wayne

 

[SoConfused]

personally don't like the HOL 90 at all would have a regular 90 there and a wye just downstream picking up the 2 inch even with a few more 45s . but you seem capable if you want to try it out ok, but not the kind of way I like to see it. thanks for showing us and sharing this problem

I keep reading and re-reading your and Wayne's posts from today trying to visualize what you're saying. It takes me a while to put it all together and understand the lingo. What is an HOL 90?? I tried looking it up but didn't find an answer.

 

[Jeff H Young]

heel outlet or low heel outlet the fitting that the 2 inch line attaches to , below the double fixture fitting sorry hope this is clear now

 

[SoConfused]

I won't have a chance to look at the rest of your question until later today, but on this point:

- Is that with a street san-tee and regular LT90 (or street LT90 and regular san-tee), or with two all-hub fittings? Because the street version should be 1.5" shorter than having touching hubs.

- If the upper horizontal segment (3" WC fixture drain) and lower segment (current 2" line going into the 3" line) were directly on top of each other (not skewed), then another option for the vent takeoff and the drop in elevation would be to use street 45 - wye with the barrel at the 45 degree angle off plumb and the branch vertical for the vent - (possibly street) 45. [That's only an option for a WC vent takeoff, other traps need to be vented before the trap arm starts downward like that.] If the misalignment between the upper and lower horizontal segments is not too great, you might be able to make that configuration work, not sure.

- Once the 2" is out of the way (if you start your jog before you get close to the earlier WC above), you have the option to cut the 4" drop from the WC, extend it downward to a lower 3x4 reducing closet bend, point that at an angle so that a short pipe and a horizontal 45 (or maybe 22.5) will let you get in line with the existing lower 3", and then use an upright combo (or san-tee on its back if you need something more compact, since you are under the IPC) to connect up to the existing vent above.

Cheers, Wayne

To your firs: That is with a regular san-tee. A regular san-tee hits the current configuration at the bottom of the collar on the existing heel outlet. I haven't seen a street san-tee but I don't think the 1.5 inches would be enough to get a long sweep 90.

To your second paragraph: Still trying to get my head around this. The misalignment between the 4 inch vertical pipe and the lower horizontal drain pipe is such that a 22.5 and a short length of pipe then a combo off plumb would line them up. That would be using a vertical reducer as I did with the other WC. I know that's not code but I don't see it causing a problem. As hard as I try I can't picture the configuration you're describing there.

To your third paragraph: If I understand this one correctly, it would be similar to what I did on the other WC but would eliminate the 4x3 vertical reducer. Is that right? Also, why isn't a san-tee on it's back a no, no like the heel outlet??

 

[SoConfused]

heel outlet or low heel outlet the fitting that the 2 inch line attaches to , below the double fixture fitting sorry hope this is clear now

Gotcha. That fitting is definitely being changed out. I'm just trying to decide the best way to get rid of that double fixture fitting that I've now cut one arm off of and the heel outlet. Part of that will of course be getting the right WC down and across to the main drain line.

 

[wwhitney]

When I have a chance I'll respond to the other parts of your post, but a san-tee on its back can only be used when the top is a vent. Since it won't normally have drainage coming in from above (only after a backup), the IPC considers that OK. A heel inlet 90 is basically the same thing as a san-tee, which is why it is not to be used "on its back" as your currently is.

Cheers, Wayne

 

[Jeff H Young]

If I had to cheat and use 1/4 bend instead of the heel outlet I wouldn't lose sleep on it then just put a 3x3x2 wye immediately downstream to pick up the 2 inch as mentioned earlier

 

[wwhitney]

4) Jeff's suggestion of replacing the (street?) double san-tee and low heel 90 with a street san-tee and a quarter bend would be the simplest option. That's not allowed by the UPC or the IPC (they require more sweep for the vertical to horizontal change of direction fitting), but it may be allowed in Kentucky. As far as I can tell from very brief research, Kentucky has it own plumbing code, and 815 KAR 20:090 Section 5 is the relevant requirement, which doesn't distinguish between quarter bends and long turn 90s. That seems weird, so I may have that wrong.

4.5) See the next post.

5) Assuming you don't want to do that, then once the 2" line is jogged out of the way, the simplest option to me is to replace the low heel 90 with a 3" san-tee on its back (where the top will now be just a dry vent) (or use a combo if there's room, but there may not be), then lower the 3x4 reducing closet bend to be at the same elevation as that san-tee (allowing for 2% slope), point its outlet to be at a 45 degree angle to the lower horizontal now 3" only drain, and connect it into the vent take-off san-tee on its back with a 45.

6) It may be possible to leave the reducing 3x4 closet elbow where it is, without having a vertical drain segment below the vent, but it's very complicated, so feel free to skip this part, I don't recommend it. What I was trying to describe in "paragraph 2" in my first post today was the pattern below I labeled A. Black is drain, blue is vent, and only the fittings are shown, straight pipe sections are omitted. Pattern B is similar, with even less height difference between the two horizontal drain sections, but you'd need to fit that blue (vent) 45 elbow up in the joist bay.

So if your current closet bend to double san-tee pipe were directly over the lower horizontal drain, either pattern A or pattern B would work fine. But it's actually at a slight skew angle, the upper run is twisted relative to the lower run. I think the angle rotation (as seen from above, call that angle A) between the two lines is probably too much to be able to handle by just fiddling with some of the joints a little. What you could do is add a street 22.5 to the lower 45 elbow. Which would work with the 22.5 horizontal if angle A is exactly 22.5.

But I also think angle A is less than 22.5. It should still be possible to make the compound turn and get the outlet of the 22.5 in the right direction at the right slope (end up parallel to the downstream 3" where the other WC is currently coming in at the combo) , but you'd have to adjust two variables: turning the 22.5 relative to the 45, and turning the 45 relative to the pipe coming down out of the wye, it would be a lot of trial and error. And even once you get parallel at the right elevation you will probably have overshot the mark in the horizontal dimension perpendicular to these parallel lines, so you'd still need a pair of 45s or 22.5s to jog back and line up with that other WC combo.

So I think (4) or (5) is better, (6) is very complicated.

Cheers, Wayne

 

[wwhitney]

PS You are correct that if the 3x4 reducer were OK, you could do the WC just like the previous one: replace the low heel inlet quarter bend with an upright combo for the vertical vent takeoff, and then use an upstream combo rolled 22.5 or 45 degrees at the appropriate location along the horizontal line to hit a 22.5 or 45 degree elbow to end up vertical below the closet flange. [With the straight inlet on the combo used for a cleanout; although as that cleanout would be in line with the upstream 2" drain before it jogs, you'd want to jog that 2" drain far enough upstream to leave say 2' clear in front of the cleanout.] And that geometry is great if you can eliminate the 3x4 reducer by pulling the WC and changing to a 3" closet flange.

Cheers, Wayne

 

[SoConfused]

4) Jeff's suggestion of replacing the (street?) double san-tee and low heel 90 with a street san-tee and a quarter bend would be the simplest option. That's not allowed by the UPC or the IPC (they require more sweep for the vertical to horizontal change of direction fitting), but it may be allowed in Kentucky. As far as I can tell from very brief research, Kentucky has it own plumbing code, and 815 KAR 20:090 Section 5 is the relevant requirement, which doesn't distinguish between quarter bends and long turn 90s. That seems weird, so I may have that wrong.

4.5) See the next post.

5) Assuming you don't want to do that, then once the 2" line is jogged out of the way, the simplest option to me is to replace the low heel 90 with a 3" san-tee on its back (where the top will now be just a dry vent) (or use a combo if there's room, but there may not be), then lower the 3x4 reducing closet bend to be at the same elevation as that san-tee (allowing for 2% slope), point its outlet to be at a 45 degree angle to the lower horizontal now 3" only drain, and connect it into the vent take-off san-tee on its back with a 45.

6) It may be possible to leave the reducing 3x4 closet elbow where it is, without having a vertical drain segment below the vent, but it's very complicated, so feel free to skip this part, I don't recommend it. What I was trying to describe in "paragraph 2" in my first post today was the pattern below I labeled A. Black is drain, blue is vent, and only the fittings are shown, straight pipe sections are omitted. Pattern B is similar, with even less height difference between the two horizontal drain sections, but you'd need to fit that blue (vent) 45 elbow up in the joist bay.

So if your current closet bend to double san-tee pipe were directly over the lower horizontal drain, either pattern A or pattern B would work fine. But it's actually at a slight skew angle, the upper run is twisted relative to the lower run. I think the angle rotation (as seen from above, call that angle A) between the two lines is probably too much to be able to handle by just fiddling with some of the joints a little. What you could do is add a street 22.5 to the lower 45 elbow. Which would work with the 22.5 horizontal if angle A is exactly 22.5.

But I also think angle A is less than 22.5. It should still be possible to make the compound turn and get the outlet of the 22.5 in the right direction at the right slope (end up parallel to the downstream 3" where the other WC is currently coming in at the combo) , but you'd have to adjust two variables: turning the 22.5 relative to the 45, and turning the 45 relative to the pipe coming down out of the wye, it would be a lot of trial and error. And even once you get parallel at the right elevation you will probably have overshot the mark in the horizontal dimension perpendicular to these parallel lines, so you'd still need a pair of 45s or 22.5s to jog back and line up with that other WC combo.

So I think (4) or (5) is better, (6) is very complicated.

Cheers, Wayne

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Hi Wayne! Thanks so much for sticking with me on this journey. In your 6) you mentioned something about your "first post today" but I only see one post from you today. I don't think it will matter though because I agree that #6 is very complicated. I do well to follow you and Reach on the less complicated options!

I feel certain that I can make either option 4 or 5 work. Am I correct in thinking that option 5 would allow for better flow of solids? I'm just wondering if the quarter bend would be a problem spot. I'll have to look at it with the san-tee to see if it seems that way in person. Do you see much difference in function of flow and or venting between 4 and 5? Thanks for sending the relevant plumbing code section also.

 

[wwhitney]

Hi Wayne! Thanks so much for sticking with me on this journey. In your 6) you mentioned something about your "first post today" but I only see one post from you today.

Post times must be displayed in the reader's local time; this is my first post today, and yesterday I made 5 posts. The last two were after 10 p.m. PDT, so apparently show up as on the next day in KY. Anyway, I was referring to post #68.

I feel certain that I can make either option 4 or 5 work. Am I correct in thinking that option 5 would allow for better flow of solids? I'm just wondering if the quarter bend would be a problem spot.

Yeah, I like 5, or 4.5 plus future 2.5, better. I can't say that 4 is actually worse, but it feels less good for the WC fixture drain to go flange - vertical - horizontal - vertical - horizontal so close together

So go for 5 or 4.5 plus future 2.5. The only advantage of 5 over 4.5 is that it lets you put in a new lower 3x4 reducing closet bend to code compliantly go down to 3", rather than relying on the improper vertical 3x4 reducer. Also, in 5, where I mentioned a 45, that could be a wye with the straight inlet as cleanout, again if you provide enough access space in front of the cleanout.

Cheers, Wayne