Flex flue tape / slight smoke at startup

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rockstarroar

Member
Jan 2, 2013
12
I've always smelt a little bit of smoke at startup on my Napoleon NPI-40 insert. Right before the pellets ignite and start filing up the firebox with smoke. Didn't think to much off it because its always done it since I moved in the house which had the stove installed prior. I just assumed the smell was from the small hole the heat exchanger cleaning rod goes through.

I was doing some maintenance today and cleaned out the access box at the bottom of the flue after I ran the soot eater down the flue. I noticed that when I started up the stove some smoke came out around where the flex stainless pipe connects to the stove pipe flue adapter. There is some tape on there (Nashua 324a) and I think it is leaking out near there. It stops once the fire gets going.

I was thinking I would just put some more tape on there, but all I have is some unmarked Nashua Foil HVAC tape at the house. I looked up 324a and it looks like its for cold weather applications, but a couple others on this forum have used it on flue pipe when doing a search.

Curious if there is a better tape, or something else to use? Stove runs 24/7 asides from cleaning, and has for the past 5 years without any issue with the tape burning or anything so I feel the 324a is safe. Just not sure if it isn't keeping a good seal, possibly due to the heat
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