Fernco-ing 3" ABS to 3" Copper DWV

[thebobguy]

I've used Ferncos in the past on drain pipes with similar O.D.s, however 3" copper has an O.D. of 3 1/8", while 3" ABS is more like 3 1/2".

The Fernco 3x3 coupling is labeled for use with copper, cast iron or plastic, so I guess it's supposed to work.

Is this a reliable connection? Will the rubber squish down tightly enough on the smaller O.D. copper?

[Terry]

I wouldn't be allowed to use the fernco here.

Your approved fittings are metal banded on the outside. That prevents the pipes from shifting after time. Something like a Mission CK33 would be the right one. they have them with one side for plastic and the other side for the smaller copper.

[thebobguy]

Thanks Terry, the Mission coupling is exactly what I was looking for.