I recently installed a Lopi Revere insert. In the top of the firebox are secondary burn tubes. I am burning super-dry juniper, 3-5 inch diameter rounds. I have noticed that when the flames are dying out and the cycle is entering coals stage, and there are blue flames flicking around the top of the firebox, the burn tubes are faintly glowing. Not super brightly, but they are glowing. Probably they are glowing when the flames are in full force, too, it's just that it is too bright to see the glow. The top and sides of the unit are nowhere near glowing; it's just the secondary tubes inside the firebox that I am talking about. I am observing the faint glow, even though the air intake is set 1/4 or less. I'd hate to think I'm overfiring the unit. Am I overfiring the unit?