With a new pellet boiler into a newly lined chimney, what's the best rule of thumb for chimney sweeping? Presumably this should be far less prone to creosote buildup than a wood stove. I asked the maintenance tech with the firm that installed the boiler, and he had no real answer. On the other hand the manual for the boiler suggests checking the chimney "regularly" -- no doubt to spare them any liability. What do folks find running pellet boilers over the years?