Non-NSF PVC fittings for DWV - Plumbing Forum

amateur · 01-31-2012, 04:11 PM

I've got a pretty tight space where I am trying to put the waste line from the toilet to the main stack, so I will have to use a 3" pipe. The stack is 4" PVC and I already have the 4" pipe coming off of it. Unfortunately, I realized after glueing in the 4" pipe that I should have used a bushing to get that down to 3" in order to fit into the space that I have available. So here's the question - have you guys used non-NSF rated fittings, such as an internal diameter coupler, and what did you think about it? My options for fittings to make this work seem to be limited and the only fittings that I can find that will work are non-NSF rated. To take it even a step further, have any of you ever used a fitting in an alternative way? I have found that the OD of a 3" fitting fits pretty well into the ID of the 4" pipe, once the molded markings are sanded off. Is there any reason not to glue the fitting inside the pipe?

**phishfood** · 01-31-2012, 11:00 PM

If we told ya, we'd have ta kill ya!

**phishfood** · 01-31-2012, 11:04 PM

On a more serious note.

The piece of 4" pipe that you have already glued in. Is that pipe foam core, otherwise known as coextruded cellular core pipe, or is it 100% plastic pipe?

The reason I ask is that the foam core is known to (sometimes) leak during test if the end of the pipe is not well glued into the fitting. The leak occurs at the top of the pipe when a 4"x3" closet flange is glued into the pipe.

In your case, it likely wouldn't ever leak in normal use, but there would be the possibility.

amateur · 02-01-2012, 09:20 PM

The 4" pipe is cell core. I would have rather had solid PVC, but the big box store only had the cell core. I am not too worried about the leakage since the upstream end of the 4" pipe will be on the outside of the connection between the pipe and the 3" fitting. For anything to flow through the cell structure, it would have to enter the downstream end and flow backwards. My bigger concern was about using the 3" fitting inside the 4" pipe. It's a pretty atypical way to go about it. It seems like it would be okay, but I know there are a lot more experienced people than me out there that might have some thoughts to share on doing it this way.

**LiQuId** · 02-01-2012, 11:31 PM

there are W.c. Flanges made that will properly fit into a 4" pipe.

**phishfood** · 02-02-2012, 12:01 AM

I think that the OP has a 4" stack with a 4" santee and pipe that they are trying to attach a 1/4 bend to turn up to the closet flange. I could be wrong, but that was my impression.

**LiQuId** · 02-02-2012, 03:56 AM

I see... I wonder then why not use a bushing then?? perhaps this is what OP means by "internal diameter coupler" I think of a bushing or perhaps something in need of a cheater sleeve and I fail to understand how this problem cant be solved with approved fittings....

Okay re-read that OP and I think I get it... so why not just remove the 4" or replace that section with a new 4x3 t wye and some couplers?

Me, I'd remove the section of 4" and bush it down though it may be a pain in the ass if the pipe has been glued in there for a while now... but still doablle,

You will need.

1 hacksaw blade, or dremel, or sawzall ( if your good with one )
1 hammer or rubber mallet
1 Flathead screwdriver

Cut the pipe off at the t wye, then cut down the inside of the pipe only untill you touch the hub. Do this on a few segments if the pipe is glued for a while.
Slam the scredriver in there and separate the pipe from the hub wallwith a twisting motion, You want it to Coil out and leave the hub wall intact. ( vice grips and a twist when you can grab the pipe helps too )
Prime.... wait a fe mins... prime again, Glue.. assemble with a twist and a push..

Done.

Make sure that the center is going to be proper on the bushed down 4x3 with it now going out 3"