Help with Code Question

[GatorDL55]

The thing that I would worry about putting a pipe inside another insulated pipe would be that the inside pipe might get too hot since it can't radiate heat out. With all of that insulation, the internal temp of the pipe inside the insulated pipe might get very extreme and cause it to fail.

 

[southbalto]

I have a brief update:

I have talked to an installer that installed Jotul stoves in Alaska for 10 years. After talking over our options, he thinks that he can install a foreverflex 5.5" liner with insulating wrap inside the existing 8" stainless steel pipe. With that insulation on the flexliner, the flexpipe would now be a zero clearance install, which should therefore make the 8" 1700* DESA pipe -- for all intents and purposes -- irrelevant.

According to http://www.chimneysweeponline.com, the ForeverFlex Pipe combined with their Super Wrap insulation will only have an OD of 7". The 8" desa pipe is an actual ID of 8.25" or so. The 8" pipe is smooth SS and the sections are snap locked together, so there shouldn't be any obstructions to getting the flex pipe inside.

What do you think of this idea? This will still be thousands of dollars cheaper than trying to put in a new Class A chimney, yet should still be WAY more than adequate for my setup. Am I missing something or should this work out just fine? Thanks again for everyone's help.

I took this week off and pulled out the chimney servicing a zero clearance unit and replaced it with all Class A. It will be connected to a new Jotul Castine tomorrow. I weighted the same question you are and ended up pulling the trigger on the new install. All and all, it was a pretty easy. I had the ZC unit and chimney out in less than 2 hours. The Class A install took a solid day.

Two things to think about.

You know Class A is the appropriate material
1000 or 1500 or 2500 dollars spread over a 30-40 year life is peanuts