What are the difference in these two? Any Benefit in using a shielded coupling over the neoprene?

Back story - What I'm trying to do is move a toilet. It is literally 3 inches from a wall, and also is 4 inches higher than the floor. The main stack came up through a concrete wall, so I believe the toilet was set this high because no one bothered to chip out the wall and put the plumbing in at the correct level. Well here I am, Ive removed the subfloor and chipped out all the concrete around the stack. I rented a chain snap and I'm about to cut out a section of the stack to drop it down to the right level and angle it away from the wall at the same time. When I reconnect using a PVC pipe, should I use one of these no hub couplings, shielded or not? Or is there a different kind of coupling I should be using with a hub. It's a 4" cast iron stack. I'm up on the second floor bath, Nothing is above it, just out through the roof for venting.

Ref. http://www.fernco.com/plumbing/shielded-couplings/no-hub-couplings & http://www.fernco.com/plumbing/flexible-couplings/stock-couplings

Thanks in advance!

Hi Neolite...


Big differences in couplings and a few concerns pop up here, so kudos to you for asking the questions!

First, never use the all neoprene clamps with SS clamps inside a home... really only for underground and even then they very rarely get approved by any plumbing inspectors, OK? I know they sell them as repair clamps, but they are not approved even though they are easy to use! So, obviously, you want shielded clamps... ;)

Now, in terms of your cast iron stack...

I don't usually recommend using a chain or snap cutter for the homeowner... these tools can crush the pipe and make the job bigger than it needed to be. Here, especially in your case, I would recommend supporting the cast iron pipe using a RISER CLAMP (sold at plumbing supply stoire) and 2"x4" studs to the ground. I would also suggest cutting the cast iron stack using a sawzall with carbide tipped blades, or even better, the newer diamond tipped sawzall blades (made by lennox).

Now, you can't just go inserting PVC between cast iron sections so you either purchase a cast iron x PVC shielded transition clamp and then transition to PVC and go out the roof with PVC or you insert a cast iron fitting into the stack and use shielded clamps to connect the cast iron fitting to the cast iron pipe. On the branch of the cast iron fitting you would still use the cast iron x PVC shielded transition clamp to change to PVC for your new work... make sense?

If you are working with a cast iron HUB then you would want to use DONUTS that fit into the hub... just need to be sure to get the right donut. In most cases, with inexperienced hoimeowners I think it is simply easier to cut the hub out and then sonnect using shielded clamps.

More questions... just let me know?

Mark