About 9 months ago I had my masonry chimney lined with a stainless steel liner. The fireplace has been sealed for 20+ years. I am hoping to finally be able to use the fireplace over the holidays. Is there any sort of break-in procedure that needs to be followed with a fireplace that has not been used in a long time and a newly lined chimney?
The 20+ years became a non-issue with the relining 9 months ago, assuming that was done properly and inspected when finished by somone qualified to inspect it (presumably the installers, in most cases.)
Always a good idea to burn a small wad of newspaper before getting a full fire going to be sure that no birds opted to nest in there these past 9 months, blocking the re-lined flue. If smoke goes up, go ahead and build a fire.
Responding to comment: correct, no "break in" is needed for a stainless steel liner - install it, use it.