I'm about to purchase new wood as I'm almost out, that could be part of the issue. I'll try to get oak or ash next.Jakee, you said you have burned only cherry. I like cherry firewood, it is a fine firewood. But, I do find that it is sooty. I have no problem with the glass on my furnace if I burn it hot. But if I try to damper it down, it will get the glass sooty. More than most woods that I burn. I think that is a bit inevitable with cherry.
Thanks for your input.