Fernco or not? 1-1/2" cast to 2" pvc

[krich]

Hello, I am new on this forum and could use some diy advise on a plumbing project. I have taken out a tub and am building a tiled shower and conc sand bed floor. I need to connect from a 1-1/2" tub drain to a 2" pvc shower drain. This is in manhatten and the existing tub drain is a metal tubing into a cast trap and horizontal run into an abs main. I had advise to use a fernco coupler on the metal vertical tubing. This would be easiest but is it reliable? Would the other option be to cut the cast trap out and somehow attach a pvc (trap) onto the cast horizontal pipe? See pics, you cant see the trap directly under the water line. Thanks

 

[Jadnashua]

Things can get really messy in a city like that...some places require all plumbing to be metal for fire code issues. FWIW, a shower drain requires the drain to be 2" minimum, so you cannot connect to the 1.5" stuff at all. They do not make a Fernco fitting that goes from different sized pipe (other than different materials say plastic to copper) that is approved for use above ground - you cannot use the all rubber version. In a multiple family dwelling (that may not apply) in most places, you are required to hire a licensed plumber to do any work, and it should have a building permit. Not something most people want to hear, but it can get messy if you don't. The plumber would know the approved way to do this job for your area and local rules.

 

[Sponsor]

 

[Plumber69]

I wouldn't use a fernco on anything. Maybe a vent if I needed to and had nothing else

 

[Jadnashua]

Just to clear up some common naming: Fernco is a company that makes LOTS of things. Similar to Kleenex for a tissue...under that same name, they make napkins and a bunch of other products. Avoid confusion...call them by their correct name. One of Fernco's products has taken on the name Fernco as a general class of things - it's a neoprene rubber sleeve with hose clamps at each end. Those can be used UNDERGROUND, where when backfilling, the pipes are properly supported. They CANNOT be used above ground and pass code. Fernco, among thousands of other products DOES make a fitting that can be used to join two pipes - a banded coupling - a thinner neoprene sleeve with a full-metal reinforcement sleeve, and then hose clamps. They also make 'donuts' to join a cast iron bell to plastic pipe in probably thousands of sizes. But, because it is not reinforced, you can't use a 1.5--2" all rubber Fernco product to joint pipe. Plus, plumbing code also prohibits you from necking down your drain. In this case, a 2" shower drain going into a 1.5" drain line, even if it eventually makes it to a bigger pipe. I think that Canada still allows a 1.5" shower drain, and your inspector might allow you to use a 1.5" shower drain, but shouldn't allow a 2" one into a 1.5" pipe.

 

[Terry]

In the 50's that used to use 1-1/2" for shower drains. That later changed to 2".
A shower with a single shower head has no problem with a 1-1/2" p-trap.
Since shower drains are now 2", I come out of them 2" and reduce down from there into the 1.5" trap and drain.
Going from metal to plastic, I use a Mission (Fernco) or other brand that is metal wrapped to prevent shifting of the pipes. I don't know what code is for you, but you already have plastic pipes there if there is an ABS main. PVC and ABS don't glue together. I use a coupling between the two to transistion.

I would lose the old cast trap.