As a new member I would like introduce myself. I live in east tn my wife and I just finished building our own home, from the ground up, with lots ofnhelp of course. We included in this build a wood furnace in the basement as well as an insert upstairs. That being said on To my question, the insert is installed with a direct connection to an 8x8 flue liner that extends 15 feet to four feet above the roof line on an exterior wall, when the stove was installed it worked great, get to temp, close bypass, lights off and cruises at around 1000 for hours, now not so lucky, with bypass open fire burns very well, what could be the problem?, clogged cat or air intakes maybe?