I am in a similar situation here, have a Factory Prefab Heatilator ZC fireplace, installed during new home construction in 1993. To add a little more complexity, mine is one of those dual sided units, sits between two rooms, finished on both sides. I am planning on removing the unit, installing a Woodstock, maybe the new Progress Hybrid on the hearth in front of one side.
My question for all of experts on this site,, is it acceptable, leagal to keep the existing Heatilator double wall air cooled 8" (at least 8") pipe, line it with a new 6" insulated SS liner? How is the existing Heatilator pipe supported? Does it rest on top of the ZC unit?
I've called a couple of on line companies that sell liner supplies, they've told me that it can be done,, one place told me that they sell something called a "Factory Built Liner Adapter" for this application. (
http://www.chimney-liner-central.com/factory_built_liner_adaptor.html)
I'm a little unsure about the advice I've been given,, just because something can be done,, it may not meet all of the requirements for insurance purposes.
If I need to replace the Heatilator pipe, install new Class A pipe, can it be done without the job turning into a major construction project? It's a straight run, two stories, the existing pipe was built inside an internal chase, no entry/exit through floors.
I live in Northeast PA, if any one can recommend a good installer or contractor who does this kind of work, would appreciate it.