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Discussion Starter · #1 ·
Hello all, I am trying to replace my old cast iron drain pipes in my basement. I have about 3 feet of cast iron to replace with 3 inch ABS piping. My cast iron goes all the way up to toilet flange. I plan on replacing the toilet as well. The rest of my drain pipes are 3 inch ABS into the basement concrete floor. The current ABS goes from concrete floor up to about where the joists are for the basement ceiling. There is a rubber coupling to connect the ABS to the Cast iron. I plan on removing all the cast iron and replacing it with 3 inch ABS piping. I believe I would need a 90 degree elbow, sanitary TEE, and about 3 feet of straight ABS piping. Obviously, glued together with proper glue. My cast iron looks to be either 3 or 4 inch cast iron. Not sure about how to do this. The top of cast iron below the toilet flange looks like 4 inch, then narrows to 3 inch. Also, why does the pipe go straight up from the main stack? Is that the vent for the waste pipe up through the roof? I will attach pictures so you can see what I mean. There looks to be a newer sub floor below the toilet and around the toilet flange. I guess the original home owner replaced the toilet about 10 years ago and put a cast iron adapter for the flange on the cast iron drain pipe. Let me know what you think needs to be done with this. Thanks, Jeff
 

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I don't want to damper your enthusiasm, but I think the San tee is going to be brutal..... The rest will be easy.

Can you tell what is connected to the top of the tee- 3" cast or 2" galvanized pipe? Whichever it is, you need to pull the tee off without damaging whatever it is connected to. Also, gravity will come into play as well. Whatever is above the tee may come falling down when the tee is removed.
Can you confirm that the pipe above the tee is secure?
 

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Discussion Starter · #5 ·
I cannot see beyond the top of the TEE. I will get a good flashlight and see if I can see what is above the TEE. Now for the rest of it, do I use all 3 inch ABS piping? The main stack is 3 inch ABS. But, I think the toilet flange is for a 4 inch pipe. As you can see it looks wider at the top of the cast iron below the toilet flange. Can I get a 4x3 Flange? 4 inch inlet to a 3 inch. Space is precious as I am working between 2 floor joists. Now, when I remove the rubber coupling on main stack below the TEE, how do I connect the ABS TEE? The is a WYE right below the cast Iron TEE. Basically its a ABS WYE, Straight pipe about 3 or 4 inches, then rubber coupling to the cast iron TEE. Do I first add ABS coupling, then small piece of straight ABS piping, the ABS TEE? Now, to proceed up to toilet, after TEE, use straight piece of ABS piping, then 90 degree elbow, the straight piece of ABS piping to 4x3 flange piece.
 

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Discussion Starter · #6 ·
Okay, I got my best flashlight in my house and looked up above the TEE. It is cast iron all the way up as far as I can see. Now, what do I do? That is a lot of weight above the TEE. How do I connect the cast iron vent pipe to the ABS TEE?
 

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Discussion Starter · #7 ·
It is not ABS above the cast iron TEE, It is metal. Looks like 3 inch size. Not sure if it is galvanized or cast iron. I scratched on it, it is rough and hard, solid pipe of some sort. Cannot get a good picture up in there.
 

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Is the wye connected to a horizontal branch?
To rebuild this, I would attatch a tee to the pipe in the wall-above the tee. Then build down the stack to a point below the wye(removing or replacing it). Final stack connection would be near the floor.
Lastly, I'd do the toilet bend and flange. Now days, most toilets are plumbed in 4x3 flanges and 3" pipe.

But, first and foremost is securing whatever is in the wall. Cast iron or galvanized is unbelievably heavy...
 

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Discussion Starter · #10 ·
Okay, the shielded coupling will be 3x3, correct? If indeed the pipe above the TEE is 3 inch and obviously the pipe below will be the 3 inch ABS I will be adding.
 

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Discussion Starter · #12 ·
You think that pipe above the TEE goes all the way to the roof and out the top of the roof? I have a ranch house. So, say about 15 feet or so in length of that pipe.
 

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You think that pipe above the TEE goes all the way to the roof and out the top of the roof? I have a ranch house. So, say about 15 feet or so in length of that pipe.
Yes, I do. But, it will most likely have a tee or two connecting to it (lav and tub/shower). This may keep it in place while you rebuild the toilet and stack. You should also replumb all of the kitchen line you can- if it's CI or galv steel.

Can you open the wall or ceiling at the hub of the tee in order to break or cut the hub with a grinder or sawzall?
 

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Discussion Starter · #14 ·
All of the drain pipes are ABS except what you see in Pictures. The TEE and up is metal or cast iron, and TEE to toilet flange is cast iron. The rest is ABS piping.
 

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Discussion Starter · #15 ·
I cannot get up in there with a sawzall or grinder. Too narrow. And if that pipe above TEE does not move downwards, I cannot cut it off. But, if it does move downwards, I can cut it if there are no other TEE up farther on that pipe above cast iron TEE.
 

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So in theory, you should be able to slide the whole stack down and cut off 6' sections and replace everything to the roof with ABS, BUT...... each section of CI has a flange to accept the one before it. hopefully the holes in the wall and floor will be big enough to accept the collar to slide through.
 

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I cannot get up in there with a sawzall or grinder. Too narrow. And if that pipe above TEE does not move downwards, I cannot cut it off. But, if it does move downwards, I can cut it if there are no other TEE up farther on that pipe above cast iron TEE.
Well, like I said in my first reply- "I don't want to damper your enthusiasm, but I think the San tee is going to be brutal..... The rest will be easy."

You do not want the pipe in the wall to move- unless you want to replace it as well. If so, then you will need to remove wall finishes upstairs to access it.
I was going with the understanding that only the tee and toilet bend are being replaced.

If you leave the pipe in the wall, pulling, lifting and moving it sideways will cause leaks on joints that are hidden above. This is why I asked if you could access the hub to cut it. If you can split the hub, the tee will come off with some brute force and mouthful of choice words.....
 
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