changing cast iron to PVC

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bartleyhs

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Hello all,
I have torn out the CI waste pipes and replaced with PVC. I basically copied the layout from the cast iron, but it occurred to me codes may have changed or I may have used the wrong fittings, so I figured it would be a good idea to get some feedback before calling it done. The layout is odd because the waste pipe going to the septic is on one side of the room and the vent stack is on the other side of the room. So under the toilet we have:
a 3” combo wye going across to the vent stack
under that is a 3” / 2” double san-T for the 2 branches
at the bottom is the closet bend out to the septic tank
I will attach a couple of pics, I hope it all makes sense.
I am particularly concerned about the double San-T I used under the toilet. I read something that made me think I should have used a double fixture T instead, and also, is it okay for it to be directly under the toilet?


Thanks
Martha
 

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Last edited:
Surprised that one of the PRO's hasn't answered yet. Just my $0.02, I would change out the santee to a fixture santee. It will help if you ever need to run a snake to clear the blockage all the way down. It will help in keeping the snake going straight through to the other connection some what. Big question is does each fixture including the toilet have a vent?
 
I appreciate your reply. I am running out of time to make the change. It would be a lot of work to change it, so I really would only do it if the sanitary tee is against code. I would love it if one of the professionals would be able to tell me that.
If its just a matter of making snaking easier I am not too concerned by that because there is a cleanout just after the closet bend (not seen in photo).
Yes each fixture is vented so I am good there, just don't want the inspector to come in and fail me for using the wrong tee.
 
Thanks Frodo. Not what I wanted to hear, but my gut told me it wasn't right. You saved me a lot of embarrassment by not having the inspector see this mess. I will be starting over. I have spent the past 2 days reading the code and previous threads here and on other forums and I now recognize a TON of things wrong with this.
I think I finally have my head wrapped around it and this time I will do a mock up and get advice before I install it.
Thanks again!
 
Last edited:
Hello all,
I have torn out the CI waste pipes and replaced with PVC. I basically copied the layout from the cast iron, but it occurred to me codes may have changed or I may have used the wrong fittings, so I figured it would be a good idea to get some feedback before calling it done. The layout is odd because the waste pipe going to the septic is on one side of the room and the vent stack is on the other side of the room. So under the toilet we have:
a 3” combo wye going across to the vent stack
under that is a 3” / 2” double san-T for the 2 branches
at the bottom is the closet bend out to the septic tank
I will attach a couple of pics, I hope it all makes sense.
I am particularly concerned about the double San-T I used under the toilet. I read something that made me think I should have used a double fixture T instead, and also, is it okay for it to be directly under the toilet?


Thanks
Martha
I wouldn’t change a thing. It will work just fine.
 
The 3” horizontal dry vent below fixture level. Just so happens posted this info a minute ago in Plumbing Codes section.

If the sanitary has a clog and water fills the system, paper and poo can end up within the horizontal dry vent. With nothing to wash it down, it will remain in the vent...
AD46626F-3BF7-4459-97F9-57F5483FE3DC.jpeg
 
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