I bought 3 1/2 tons from the old Harmony site before the cold weather set in and have been burning my stove for at solid 2 months and have never given thought to how it burns, at least until I was at my dads the other day. We both have the same stove, same draft readings, the only difference being the coal source. I tried a few hundred pounds of the coal my dad is using, and I had to really back the feed stroke down to keep from pushing hot coals off. Not sure if I'd be willing to drive to Turbotville from Shamokin to get coal though, but if I coud back off my feed like that, I'm going to assume I'd save a good bit of coal over what I am currently burning. I get good heat from what I am using now, but I know when I need to get more coal, I'm going to try somewhere else.