Advice needed: 4" CI toilet drain to 3" PVC

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JorRa

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Hi all,
New poster on the forum, been lurking a bit. I have an upstairs toilet that was leaking. Long story short, there is a hole in the lead bend so it needs to be removed. Cast pipe is 4". It had been worked on before based on cut planks when I tore the floor off..The hubs of the cast sit proud of the floor joist so I want to get those out. I am thinking of cutting the section between the 45 degree elbow and the stack and then replace with 1/8" per foot pitched 3" PVC and a shielded Fernco on the remaining cast pipe.

My main question is, will a horizontal 45 degree PVC elbow cause problems or should I do two 22.5 degree elbows for less of a tight turn? is there a better option for this bend? Toilet needs to stay where it is.Thanks!
upload_2021-10-22_13-0-8.jpeg
 

Tuttles Revenge

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You can install a sheilded 4x3 reducing transition band and use a 45 no problem. Less fittings the better. Grade should be 1/4" per foot and you should be able to maintain that in the floor given you're removing quite a bit of material with the old cast hubs. Use a 4x3 spigot closet elbow at your toilet which will stick up through your finished floor. You can then cut your closet ell flush with the sub floor and glue in a straight closet flange that will be flush with your finish floor, or even install the flange on top of the finished floor.
 

JorRa

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Thanks!
So you recommend 1/4" per foot pitch not 1/8"? I swear i kept reading 1/8" but I could be wrong lol...I got the PVC in and was aiming for 1/8" grade but the closet elbow is out of level by approx 1/16". If i tend towards 1/4" pitch it becomes level.
 

Reach4

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So you recommend 1/4" per foot pitch not 1/8"?
You probably read that 1/8 was acceptable but not preferable.

I did not completely follow your end result, but there are some nice no-glue closet flanges. Those get you a do-over, where glue is final.

One type is the outside compression Code Blue units, and there is the inside Push-tite and more.

Are you feeding into a 4x3 closet bend, which has a 4 inch input and a 3 inch output?
 

JorRa

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Hard to say where I read it at this point in my research. I probably (mis) read something here or elsewhere on the internet in trying to figure out how to do it right. Now that I am at the point of install, I am double checking things (glad I did).



So pics below...I ran out of enough length and my two local stores are out of 3" pvc so used a coupler (bad idea?)
upload_2021-11-2_11-37-17.jpeg


the CI stub at the stack actually slopes down hill (Is this a big issue for a short run?). Before I cut the old pipe out, I verified it was cantilevered off the stack with zero pitch or support... not touching the blocking that was intended to support it as it was. Based on the witness marks on the CI pipe and blocking, I am guessing the toilet and user were pushing it down because the toilet and flange were in contact so I believe the old pipe was level or sloping down a bit.
upload_2021-11-2_11-37-47.jpeg


shielded coupler installed (is it normal for the metal band to deflect like that?) PVC slightly pitched up:
upload_2021-11-2_11-39-6.jpeg


1/4" per foot pitch on long leg:
upload_2021-11-2_11-39-58.jpeg


4x3 closet elbow slightly out of level front to back:
the direction parallel to the pipe is out of level due to the intentional pitch so being out of level to that degree is not an issue even front to back correct??
upload_2021-11-2_11-43-30.jpeg


I am going through a lot of effort to get this closet level while I don't know what the floor joists and sub floor will have in store for me...when I get the flooring in, it may end up being in a different plane altogether. I just am wondering how much forgiveness I have. I will have to look into no glue options.
 
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JorRa

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Anybody have thoughts?

1. Is the warped band on the shielded fernco after torqueing to 60 in-lb normal?

2. How bad is the negative pitch on the cast stub going to the stack. it is basically a 1/4" per foot pitch going up hill. but the old pipe was probably like this too and flushed nearly fine, little slow to me but not a plugger.....Wondering if since its 3 going into 4" the low spot (where the shielded coupler is) will fill in and level things out? If I knew the Fernco donut was a sure fit, I'd drill out the lead and pop it in but worried if i get the old CI out then cannot find a donut that fits.

3. is the closet elbow being tipped back out of level a bit compounded with being out of level side to side due to intended 1/4" per foot pitch going to be an issue when I go to screw to the floor and set the toilet with a wax ring?

Thanks all!
 

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shielded coupler installed (is it normal for the metal band to deflect like that?) PVC slightly pitched up:
I would wonder if you mis-measured the cast iron side before picking the coupling.

Any thoughts?
I don't think a plumber will endorse an uphill flow. I think it may work fine. I am not a plumber. But your PVC should get the right slope, I would think.

But that picture of the level on the PVC next to the cast-- couldn't you raise the PVC before tightening down the coupling?

3. is the closet elbow being tipped back out of level a bit compounded with being out of level side to side due to intended 1/4" per foot pitch going to be an issue when I go to screw to the floor and set the toilet with a wax ring?
I was a bit surprised that you chose a hub input closet bend, since that would usually be chosen for a deeper-set bend. You are pretty much committed to a glue-in flange. Maybe you could glue a piece of pipe in there, and use a Genova Products 75158S. I don't know about the vertical distance match-up. But that flange should give you a little ability to tilt a tad.
 

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I would wonder if you mis-measured the cast iron side before picking the coupling.

CI pipe OD is 4.52" with calipers. I figured it did this because the PVC side has more rubber to compress as the band tightens.

I don't think a plumber will endorse an uphill flow. I think it may work fine. I am not a plumber. But your PVC should get the right slope, I would think.

But that picture of the level on the PVC next to the cast-- couldn't you raise the PVC before tightening down the coupling?

I can raise it but then the closet elbow tips back more out of level. Not sure how out of level I can be.

I was a bit surprised that you chose a hub input closet bend, since that would usually be chosen for a deeper-set bend. You are pretty much committed to a glue-in flange. Maybe you could glue a piece of pipe in there, and use a Genova Products 75158S. I don't know about the vertical distance match-up. But that flange should give you a little ability to tilt a tad.

the pipe sits right next to the top edge of the joist by the closet elbow when I put a 1/4 pitch on it....not much room. I have a 4x3 street elbow too but I estimate I would have to cut too much off for the flange to engage when I add about 2" above the joist for 1-1/4" subfloor, underlayment and tile. goal being for flange to sit on top of the finished tile floor.
 

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If I interpret correctly, the top view of your rag shows a tilt that you cannot blame on the cast iron.

So if you want to be able to rotate that, how about cutting that 3 inch pipe, and inserting a Fernco 3005-33 to connect back up. The coupling lets you rotate. Alternatively, you could use a Charlotte ConnecTite fitting. https://www.homedepot.com/p/Charlotte-Pipe-3-in-ConnecTite-PVC-DWV-Coupling-CTT001001200HD/301188379

And if you cut out stuff, you could use maybe 2 45s and get more freedom in lining stuff up.
https://www.homedepot.com/p/Charlotte-Pipe-3-in-ConnecTite-PVC-DWV-Coupling-CTT001001200HD/301188379

There are 90s too.

As far as how much tilt is too much, you may presume that people can look at you level bubble and know how many degrees of tilt you have. I don't know what the markings on your level mean, other than center.
 
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JorRa

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The top down pic with the rag, the closet bend, is not to blame on the CI, I thought I had it aligned during dry fit but it glued together a tad crooked....I did think of the Fernco in place of coupler as I was gluing the coupler in but it was too late. Good idea.

the level bubbles with five lines indicate pitch. Zoom in on the picture below shows 0, 1/8,1/4,3/8, 1/2....units are inches per foot. The level with the blue bubbles has one too. In the picture on the closet elbow with the rag, its the top vial in the pic. So the inlet of the closet bend is 1/16-1/8" per foot. In that picture, if I put a 1/16" shim under the one side, the level would show level.

I am thinking to drill out the lead/oakum but the hub is a 4" XH and I don't see any 4" XH to 3" PVC donuts available anywhere, just 4" service weight to 3" PVC, which has an undersized OD....part of me wants to cut that section of stack out but man I don't need any more stuff to do right now lol. If the plumbing wasn't going to be closed up in the joist cavity, I'd chance the cast pitched in the wrong direction but I don't want to have to tear in to the cavity if there is a problem.

index.php
 

Reach4

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the level bubbles with five lines indicate pitch. Zoom in on the picture below shows 0, 1/8,1/4,3/8, 1/2....units are inches per foot.
You match the mark with the middle of the bubble? So the picture shows a slope the wrong way of about 3/16 inch per foot?

In that picture, if I put a 1/16" shim under the one side, the level would show level.
Level is what -- 3 inches long?

I am thinking to drill out the lead/oakum but the hub is a 4" XH and I dont see any 4" XH to 3" pvc donuts available anywhere, just 4" service weight to 3" pvc, which has an undersized OD....
https://www.fernco.com/plumbing/donuts-o-rings/donuts
If you have dimensions, they can tell you what you need and help you order that. Usually only a few sizes are stocked at stores.

So anyway, if you stay with that cut off pipe in place, I have to think you can make things line up better. What did you think about the idea of two 45s?
I just am wondering how much forgiveness I have.
I would think 3/16 per foot tilt would work. Wax adjusts.


I will have to look into no glue options.
That is where I think the spigot-topped closet flange would be better, rather than a hub top.
 

JorRa

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both levels are the same regarding pitch reading...you get the pitch indicated by the line when the edge of the bubble touches it. below, right edge of bubble in the middle of the picture is touching 1/4" per foot mark (3rd/middle line). it is sloped in the right direction.
index.php



Not sure I follow you on the two 45 elbows. is that if i cut out that section of the vertical stack and put in pvc?
 

Reach4

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I did not follow your bubble tutorial, but that's OK.

Not sure I follow you on the two 45 elbows. is that if i cut out that section of the vertical stack and put in pvc?
Brain fart. Two 22.5s was what I had in mind to give you some extra potential adjustablity.
 
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