PVC to Cast Iron Toilet drain... which Fernco?
#1
03-12-17, 11:29 AM
Join Date: Apr 2008
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PVC to Cast Iron Toilet drain... which Fernco?
I had a broken toilet flange. I cut off the old lead drain pipe, leaving a 1.5" stub before the cast iron fitting. How should I connect the new PVC pipe? I tried to link pics of the possible solutions.
- Use a shielded 4" Fernco coupling to a PVC 4" to 3" reducer, then 3" PVC pipe. Pic#2
- Pass 3" PVC through a Fernco 3" to 4" reducing coupling, with PVC extending deeper into the Cast Iron. Pic#3
- Your incredible solution
#3
03-12-17, 06:01 PM
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Based on the 4" pipe to street elbow to flange being too high, I plan to reduce the pipe size to 3"... see below. I've also been told that 3" is better because it flushes at a higher velocity.
The distance from the top of the stub to the top of the rafter is 1.75". The rise for the 4" PVC Street elbow is 3.25". 3.25 - 1.75 = 1.5" above the rafter.
I planned to use 0.75" plywood + 0.5" backboard = 1.25"
That leaves me with a street elbow 0.25" above the backboard before I attach the flange. As I understand it, the flange should sit flush with the backboard, not above it. Am I wrong - should the flange sit atop the level of the floor tile? How would I screw down the flange if it is sitting on the tile?
The distance from the top of the stub to the top of the rafter is 1.75". The rise for the 4" PVC Street elbow is 3.25". 3.25 - 1.75 = 1.5" above the rafter.
I planned to use 0.75" plywood + 0.5" backboard = 1.25"
That leaves me with a street elbow 0.25" above the backboard before I attach the flange. As I understand it, the flange should sit flush with the backboard, not above it. Am I wrong - should the flange sit atop the level of the floor tile? How would I screw down the flange if it is sitting on the tile?
