Fernco on 3” drain line
buried fernco and backfilling?
plumbing - Fernco coupling to join ABS drain pipes under basement? - Home Improvement Stack Exchange
What is the best Fernco rubber fitting for cast iron to PVC?
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I am redoing my master bath and needed to relocate my drain lines. In the process of following the former vanity vent into slab, I busted a 3x2 eye. I have reassembled using a Fernco 3x3. Any issue with putting this under the wall? To complicate things the drain line runs under a load bearing wall and turn down footer.
Be quite difficult to use a normal abs coupling here. The couplings have a stop built into them and you typically need flexibility in the two ends being joined. These look concreted in. If the connection is going to receive concrete on top of it I don't see any risk of this separating. Rubber does tend to age, get brittle and crack over time. I'd probably just embedded it in concrete on all sides, if the rubber does die overtime at least you still effectively have a concrete pipe directing the effluent into the other portion of pipe.
One thing I've done in the past is to take a hole saw and drill out the stop in a standard abs coupling, then slide the coupling onto one side of the pipe, abs glue the two sides and slide the coupling over top the two pieces. The sides need to be quite clean and I did this with 2" pvc last time. I am not sure how much force would be required on a 3 or 4" abs to pull the coupling over the glue. I don't think I'd do that in this case.
Misalignment or size change would be a reason to to use a Fernco. I have also used them to cut an existing pipe and add an additional drain; this may be the reason it was used with a wye to the left. If the pipes are in the ground or under footings this is the way to make a connection as there is probably not enough flex to add a glued fitting--we cannot tell with the limited photo.
Would I try to make the joint perfect? Probably not it comes down to if it’s not broke don’t fix it. I have found much worse alignments due to tree roots and settling.
I have not had problems with Ferncos passing inspection when converting sections of cast to plastic both inside and outside.
P3000-44 and P3005-44 seem very similar in rubber thickness, but P3005-44 is $2 more expensive.
I feel the unshielded longer coupling is better because it allows you to easily slide the coupling all the towards one pipe and then slide it back so that it couples the two pipes together. The other two have a lip in the middle, and this makes it a bit more difficult.
Is there any situation where one would need the rubber to be shielded?