Venting for Napolean S25 insert?

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New Member
Oct 31, 2022
Long Island
I have a Napolean S25 that was just delivered to me a few days ago and I'm getting ready to do the job. I had expected to get a 15 foot 304SS liner from Lifetime chimney with an appliance adapter, but after cleaning the flue and fireplace and getting inside there with a flashlight, I'm seeing that this is about as straight and easy a shot as you can ask for. I'm inclined to use rigid sheet metal pipe instead of a flexible liner.

Question: What is the best rigid material to use here? I can get SS round pipe from the sheet metal supplier and screw them together, but I do see this: https://www.rockfordchimneysupply.c.../304l-stainless-steel-rigid-chimney-liner.php from Rockford. I'd rather get something locally.

When installing rigid sections, do you seal them up with retort cement or silicone? Or just rivet them together?

Thanks for any advice.
Rigid sections get riveted together with stainless steel rivets. Will you have clearance for insulation on the liner?
If you want it to be code compliant you need to use a ul listed liner system not just stainless pipe from a sheet metal shop
Hello, thanks for the replies. I have an 11x11 square clay flue tile with a straight shot down to the fireplace. So a 6" with rigid liner insulation ( will be around 7-1/4" diameter.

So the Rockford Rigid liner looks Kosher but I can't find any UL ratings for it. I'll email them to ask.
There really isn't any benifit to using rigid over heavy wall flex liner. And you will need flex through the old damper area regardless.