Hi, I have been running my Regency i2400 insert for about 8 years now. My wood is mainly sugar maple with around 22% humidity. No problem bringing the temp of the stove to 500 / 600 F. I close the flu leaving about one inch of opening. I find that with time , my insert is losing efficiency concerning burning time. I am getting about 4.5 hours of good heat but have to reload after 5 hrs. Anybody experiencing the same burning time with a Regency medium insert. The specs say 8 hours, there no way I ever got that kind of burning time.