Put in a dishwasher and was working on the drain when I noticed the 2" cast iron drain pipe wasnt in very good shape. I spliced it with a sawzall ans the put pvc in and tried to use a boot on each end but it still leaks. Then from the cutting another joint in it started to leak. Ive decided its time to replace it with pvc. My dishwasher will feed into it along with my washer and kitchen sink. So i have a couple of questions.
1) Should I replace with 2" pvc or should I go to 3" pvc?
2) my plan is to replace with the cast iron with pvc all the way back to 4 inches or so from the main drain. The joint for the cast iron appears to be leaded in and i dont want to mess with that. So my question is what do i do with the place the pvc meets the cast iron? I thought about a boot but can't find one that fits. I would need a 2' to 21/4 " or something like that. Any help is greatly appreciated.

"what do i do with the place the pvc meets the cast iron?"
I don't recommend Fernco Neoprene Couplings for anything except a temperary repair. To couple a bald end of a piece of cast iron to a bald end of PVC I recommend using a No-Hub Band.

"1) Should I replace with 2" pvc or should I go to 3" pvc?"
If the piece leaded into the main is 2" then increasing the PVC to 3" would still get choked down to 2"at the joint. However, since disposals and dishwashers were added to the sinks drainage we increased to three inches from two.
Good luck, Tom

Wanted to start by saying this site is very helpful. Thanks to all who participate. As my thread above states I replaced a 2" cast iron drain pipe with pvc. I then noticed I have no vent at all. So I have an upstairs bathroom and sink. Downstairs I have a dishwasher, washer, 2 sinks, toilet, bathtub. Woould one drain pipe suffice for everything? If not how many should I have? Also could I just splice the upstairs sink drain and take it on outside for a vent? And finally is 3/4 drain pipe big enough for a dishwasher drain ?

" I then noticed i have no vent at all."
You had no vent on what? The entire house? The downstairs group? Please explain in detail.
"So i have an upstairs bathroom and sink. Downstairs i have a dishwasher, washer, 2 sinks, toilet, bathtub. Woould one drain pipe suffice for everything?"
Would you be asking about the house main? A branch drain? What size are we talking about? I just don't have enough details to answer in depth

" could i just splice the upstairs sink drain and take it on outside for a vent?"
To vent what? The sink? The entire group?

"finally is 3/4 drain pipe big enough for a dishwasher drain ?"

A diswasher discharges through a hose which is connected to a disposal or the sink drainage. What are your plans?
You just haven't furnished enough details. Please explain a little farther. Regards, Tom

I mean the whole house has no vent. So upstairs I have a toilet that has 5" pvc that runs to the 5" main in the basement. The upstairs sink has 1 1/2" pvc that connects to main in basement close to the connection for the upstairs toilet. Down stairs the tub drain is cast down to the main and the toilet is also cast 5" to main. The sink is 1 1/2" pvc to main. Then there is the dishwasher, kitchen sink and washer which al connect to a 2" pvc pipe that connects to the main at a higher level than the rest. Would splicing the upstairs sink and extending it outside be enough or should I vent the 25' 2 inch pvc as well?

Also the dishwasher is in an island with an electric range. I have ran 1/2" cpvc for the hot water connection. I also have a 3/4 inch barbed connection for the dishwasher drain. Its 3/4" pvc for about 3' and then it hits the 2" pvc drain.

Hey Red,

To bring your house up to code every fixture that has a trap must be vented.
If it's been working for all these years then I would leave it be unless you're willing to shell out big bucks.

"the dishwasher is in an island with an electric range. I have ran 1/2" cpvc for the hot water connection. I also have a 3/4 inch barbed connection for the dishwasher drain. Its 3/4" pvc for about 3' and then it hits the 2" pvc drain."
3/4" PVC should handle the discharge from the dish washer. Will the hose be looped to provide a air gap? What 2" drain? Is the drain trapped ? Please explain. Regards, Tom

Im trying to have my galvanized drain pipes fixed because it has a crack at the T union of the pipe and not enough space to work with. How should I go about this. Im trying to get a plumber to fix it but Im not to knowledgeable if the price is right for the job? I need your opinion.