I need to wye into a tight spot on an existing under slab 4" PVC sewer drain. The location is underground and regularly damp/wet. I plan to use a Fernco coupling but have not found reliable information as to the best solution:
Another consideration in my case is the outer diameter of my PVC sewer pipe is 4.2"
The Fernco Proflex 3005-44 gasket has an inner diameter 4.44" while the Fernco flexible has an inner diameter of 4.5". Are both of these connections even suitable for my application? I called Fernco and they recommended I use the flexible coupling. I didn't find this answer reliable as Fernco actually makes a Proflex meant to connect 4" sched 40 PVC to 4" thinwall PVC (gasket ID 4.44" to gasket ID 4.16"). Interestingly, they do not make any thinwall to thinwall couplings. Fernco wasn't able to provide any explanation on this topic..
I would appreciate any clarification or what plumbers' usual practices in this case would typically be.
Thank you
- Fernco Proflex 3005-44 with a stainless steel sleeve over a thinner neoprene gasket.
- Fernco 1056-44 flexible coupling made with thicker flexible PVC.
Another consideration in my case is the outer diameter of my PVC sewer pipe is 4.2"
The Fernco Proflex 3005-44 gasket has an inner diameter 4.44" while the Fernco flexible has an inner diameter of 4.5". Are both of these connections even suitable for my application? I called Fernco and they recommended I use the flexible coupling. I didn't find this answer reliable as Fernco actually makes a Proflex meant to connect 4" sched 40 PVC to 4" thinwall PVC (gasket ID 4.44" to gasket ID 4.16"). Interestingly, they do not make any thinwall to thinwall couplings. Fernco wasn't able to provide any explanation on this topic..
I would appreciate any clarification or what plumbers' usual practices in this case would typically be.
Thank you