Home>Discussions>PLUMBING>3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
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MMeehan
3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

I have an older house and the main drain that goes to the floor has a coupler between the 3 Inch PVC to the Old Cast Iron Pipe. It has started leaking a slight leak when running any water. Is there a good way to fix this? Should I emery cloth the cast iron side to remove anything there and get a new coupler and replace the coupler? Or is there something I can apply to the cast iron to better seal it? After sanding down the cast iron and getting a new coupler? Any suggestions will be welcome?

Thanks,
MMeehan

johnjh2o
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

If there is no hub on the cast iron what you need is a banded coupling.
http://www.fernco.com/plumbing/shielded-couplings/proflex-couplings

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Thanks for the link but it is Fernco that is on there but it is only 2 1/4 from the top to the bottom the ones pictured in the link appears to be much longer but the one I have on it now has the collar around the entire coupler. I guess I am missing something if Fernco is what was used before just seem a little short in overall length? How long should it be for a 3 inch pipe to 3 inch pipe?

Have they changed the design and length of these type Fernco Couplers?

MMeehan

A. Spruce
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Fernco is the brand name of the coupler itself, there are other brands and styles. There are basically two types, one has an aluminum jacket, one does not. I am not sure what the purpose of the jacket is.

dj1
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
MMeehan wrote:

Thanks for the link but it is Fernco that is on there but it is only 2 1/4 from the top to the bottom the ones pictured in the link appears to be much longer but the one I have on it now has the collar around the entire coupler. I guess I am missing something if Fernco is what was used before just seem a little short in overall length? How long should it be for a 3 inch pipe to 3 inch pipe?

Have they changed the design and length of these type Fernco Couplers?

MMeehan

It's 2-1/4" long for a 3" x 3" coupling.

dj1
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
A. Spruce wrote:

Fernco is the brand name of the coupler itself, there are other brands and styles. There are basically two types, one has an aluminum jacket, one does not. I am not sure what the purpose of the jacket is.

The coupling with the metal shield is known as "no hub coupling" and is more rigid.

The one without the shield is more flexible.

A. Spruce
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
dj1 wrote:

The coupling with the metal shield is known as "no hub coupling" and is more rigid.

The one without the shield is more flexible.

Well Yeah-uh! but why is one used over the other?;)

dj1
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?
A. Spruce wrote:

Well Yeah-uh! but why is one used over the other?;)

The only explanation that I have is: for vertical piping you use the shielded coupling, for more support.

A. Spruce
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Maybe John can elaborate for us?

johnjh2o
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

DJ1 has it correct. If you used the one without the band on a vertical line the weight of the pipe would buckle the coupling. This can also happen on a horizontal line that wasn't supported on both ends of the coupling. The only place that I will use the un-banded coupling is in a ditch. Even there they can become misaligned.

MMeehan
Re: 3 Inch Cast Iron Drain Pipe to 3 Inch PVC at Coupler slight leak?

Does Fernco make different length couplers the one I have is only 2 1/4 in length for a 3 inch pipe is there one that is longer what about the Fernco ProFlex is it longer of just the same size?

Again could I sand down the cast iron pipe to make it more uniform as to possible have a better connection / seal for this where it is leaking from???

Just trying to fix this and would like to learn more before I head to a plumbing supply and know more of what I am looking for?

MMeehan

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