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Chimney Liner Leak

Posted: Wed Mar 13, 2019 8:39 am
by michaeldrehl
Hi,
I think I have a leak in my chimney liner. Below is an image of the boiler exhaust pipe going into the chimney liner. Please note the red corrosion near the entrance.
The masonry brick chimney is located inside of the structure of the house and is lined with corrugated stainless steel chimney liner. It is not insulated. I wonder why this corrosion is happening.

Thank you!

Re: Chimney Liner Leak

Posted: Wed Mar 13, 2019 9:16 am
by A. Spruce
If I had to hazard a guess, it would be sweating. Moisture condensing on the pipe due to the temperature difference between the plaster wall, pipe, and ambient air. From the looks of it, this is a pretty old flue, it wouldn't hurt to have it checked. Surface rust doesn't hurt anything, scaling rust, which the pic is beginning to indicate, is active and penetrating through the metal. Once the metal is breached, it is a serious hazard for both fire and asphyxiation.

Re: Chimney Liner Leak

Posted: Wed Mar 13, 2019 12:50 pm
by michaeldrehl
Hi Spruce,
Thank you for your reply.

I just had the chimney liner installed two years ago. The masonry chimney itself is very old. Probably over a 100 years old.
Should the metal have corroded as it has in the picture. It is just two years old.
What do you think it could be?

Re: Chimney Liner Leak

Posted: Wed Mar 13, 2019 2:24 pm
by A. Spruce
Another thought that comes to mind is that flue exhaust is acidic, so that in combination with condensation is probably where the rust is coming from.

I would scratch at it, see how bad it is, if it's little more than surface, you could probably spray it with a little conversion primer to eliminate the rust, then follow up with some paint. Not sure how hot this particular pipe gets, so heat resistant paint is probably the route to go.

If the rust has weakened the pipe, then replace it. You may also want to make sure that everything connected to this flue is drawing properly and not back-drafting.

Re: Chimney Liner Leak

Posted: Wed Mar 13, 2019 6:32 pm
by Shannon
I am surprised at the rust on that new of chimney.
Maybe the cap is not sealed well and letting moisture in as well? This appears to be a turn in the pipe so maybe moisture is being trapped as well and is sitting there ?