I recently had all the plumbing replaced on the first story and basement level of a 2 1/2 story house. I totally gutted the first story bath so I had open walls and took advantage of that to replace the plumbing back there. The second story bath is directly above the 1st story.
The stack was cast iron and a lot of steel drain pipe. We replaced all we had access to with PVC.
The second story bath has new PVC from the sink down, the toilet down and the bathtub down.
After doing this the slight odor of sewer gas that we discovered when doing the plumbing changes still remained.
This leaves only the 3" cast iron stack from the second story to the roof and a sink vent line on the second story to the cast iron stack to be the culprit.
Please see drawing for details.
Obviously I need to replace some pipe to get rid of the sewer smell. I am not afraid to tear into things but do like to think through and get advice. The house has old wood lathe and plaster so repairs are a little more challenging but not too much. I have done a lot of repairing here so no problem in fixing more access holes wherever needed but again, I just don't want to creating holes if I don't need to.
In the drawing the gray and dark gray pipe are what I need to replace. I have access to the stack from the attic and will have to cut that up in probably two or three pieces to maneuver it out of there.
My question is for the reason that I may be able to change my approach on the fix which would eliminate some need for opening up an access hole.
As indicated in the drawing....
Do I need that vent line from the sink or can I eliminate it?
I know it was there for all these years but that doesn't necessarilly mean it had a functional purpose. With the drain pipes running vertical, then 45, then another 45 and then final pitched to the stack... I don't understand the venting requirements in this case.
Thanks for any input.