I have a Harman Accentra insert. As others have mentioned, the fan is definitely on the loud end of the spectrum. The noise, however, is much less when the fan is set to a lower speed. Does anyone know how much efficiency I lose if I run the stove with the fan at a lower setting? Will the fan blow less air, but hotter air? Or will I lose a lot of hot air up the chimney? How about using a lower fan setting on warmer days?