Is a PVC Coupling Reamer Effective?

Question

In my area code allows me to keep my 1 1/2 inch drain for new shower which I thought would save a lot to not have to cut out the stack and replace the wye to the toilet and present bathtub drain etc. having a dedicated vent only 28 inches away from the new shower drain makes even the extended 1 1/2 inch drain work. Funny I had 2 plan review guys at RBD say I could not use a reducer on the drop pipe since most of the tiling pans have 2 inch pipe, but finally the chief inspector came over and said no problem. However I have recently seen a reamer that would allow me to ream out the 3 inch stack coupling that currently has a 3 to 1 1/2 inch adapter, and since I already have most of the subfloor up anyway to replace water damage and move a floor heater duct into the wall etc, another 2 feet (where the tools are) would not be a huge deal if they work as intended. Would it be an advantage to increasing to a 2 inch drain and can I expect the reamer to do what it’s supposed to so I am not stuck with cutting out the stack? Showing the new extension which of course will be installed below the joists.

Answer 1

Yes, the "socket-saver" or "hub saver" or "plastic pipe reamer" tools work.

As with all tools, there are better and worse ones, and generally the better ones cost more. I would see if you can rent a good one from a tool rental place rather than spend a lot on a tool you will probably only use once; or spending not much on something from the folks that sell cheap stuff that looks vaguely like it will work but actually ends up costing you more because it doesn't cut properly, isn't the right size, etc. and generally doesn't actually work.

Hmm. I think there's a prior question where there are pictures of various versions. Let me see...here we go. As noted there, the cost of a good one you'll only use once may well be less than having a plumber come by to do that part, if you could even get a plumber to come by and do just that part. But rental would be preferable.

As for 2" shower drain .vs. maintaining 1-1/2" grandfathered, I tend to think that there's a good reason they changed code, when they bother to change code, so it's preferable to follow current code when you can, even if the inspectors would let you use the grandfathered size. 1-1/2" pipe has 56% of the hole that 2" pipe does (that r-squared factor for area of a circle...)