Leaking Fernco

thaas53 · May 12, 2010

Thanks to everyone here I was able to put in a washer drain in our mudroom. However, now I am having an issue with the drain stack leaking. There is CI in the floor that I cut about 1.5" above the flange. I then connected my new PVC stack to the CI using a Fernco connector. It has developed a leak out the top of the fernco connector and I can't figure out why. The clamps are tight. It is a slow leak that doesn't really start until a bit after the water is flowing. I've attached a photo that shows the leaky spot. Any ideas on how I can solve this?

Thanks.

SewerRatz · May 12, 2010

Assuming you have torqued the clamps to 60 inch pounds each. The leak can be caused by the stack filling up with water (partial blockage). One thing to note you should of used a shielded coupling instead of a plain fernco.

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hj · May 12, 2010

You used the wrong coupling, but water would NOT leak upward out of that joint unless the pipe itself was full of water ABOVE that point. The law of gravity says that water CANNOT run uphill. And without seeing the rest of your installation, and what is ABOVE your connections, we are not even sure if the installation was done correctly.

thaas53 · May 12, 2010

Only thing above this is the washer drain and a drain for a bathroom sink on the other side of the wall. The rest are vents. As you can see I did originally use the shielded coupling but thought that might have been my problem and replaced it with this larger standard one. The drain in the floor also connects to the shower stall and the toilet in the bathroom. Neither of these back up.

theBigSee · May 12, 2010

This is very intriguing because I was under the impression that it's virtually impossible for one of those to leak! It just seems like it is such a snug fit, especially when tightened. Clearly there's some sort of standing water there, but I would think that it would still not leak even if under pressure. Makes me wonder if the pipe is cracked or deformed?

Shacko · May 12, 2010

Ferncos are made for the specific pipe they go to, did you buy one that went from pvc to sv cast iron? If you didn't cut the pipe to where both ends almost touch you may have a bad joint; not enough pipe for the joint to seal correctly.

It looks like that stack picks up other fixtures overhead, that could be where the water is comming from.
If it is a live stack? the piping you've done is totally wrong, you can't vent into a live stack

thaas53 · May 12, 2010

The CI is slightly smaller (maybe 1/4") in diameter than the 4" PVC. There is a fair gap between the CI and the PVC, maybe 2 inches.

Nothing is above, it vents directly through the roof above what you can't see in the picture.

Jadnashua · May 12, 2010

The banded couplings come in various sizes...it should be a tight fit on each pipe before you tighten the clamps. You may have to go to a plumbing supply house to get one, or order it online.

Rich B · May 13, 2010

I joined PVC to C.I. in a few places and found I needed shielded couplers with 2 different I.D.'s to get a proper fit from 4" PVC to 4" C.I. They were listed for PVC to copper if I recall correctly. The C.I. is smaller O.D. than the PVC. A shielded coupler properly installed is very snug and the pipes should almost butt together with maybe 1/4" of gap.

Are you sure the leak is not coming from a glue joint above the Fernco?

hj · May 13, 2010

If the leak is not being caused by the water backing up in the pipe, then it is NOT the coupling leaking. The joint above it is probably the reason you get water on this coupling AND the previous one. Your chances of getting defective couplings of two different styles would verge on ZERO +/-.

thaas53 · May 13, 2010

Thanks for the hints everyone. Guess I have a few things to check now that I hadn't thought of. I'll get the proper couplings with the shielding and be sure they are the proper size.

I'll let you know how it goes. Probably get to this tonight.

Terry · May 13, 2010

If the cast is 4-1/8" that's a copper size.

You may need to pick up a copper by cast irong mission coupling with the shielding.

It's nice to see a washer and lav plumbed correctly.
The only thing better would have been the combo on the washer vent, but I still give you a gold star for the job.

thaas53 · May 17, 2010

hj said:
If the leak is not being caused by the water backing up in the pipe, then it is NOT the coupling leaking. The joint above it is probably the reason you get water on this coupling AND the previous one. Your chances of getting defective couplings of two different styles would verge on ZERO +/-.

hj, after looking at this over the weekend, you are correct. The joint above has a slow leak on the backside which then makes it seem like it is the fernco, when it is not.

Thanks for the tips everyone, I'll be redoing some of this. I was able to locate the correctly sized shielded couplers as well so I'll be putting them in at the same time.

Thanks again.

Leaking Fernco

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