We have people looking for the better wood for projects like Lon said.
The Heisler can burn almost any type of wood, but some, like cottonwood burn much cooler and have more ash to deal with. We save the cottonwood for firemen that never show up to split and stack the wood. If we are there to stack our own, I have asked for pitchy pine, but that also depends on what there may be to choose from. Some of the wood we had the last year we ran the 3 for passenger service was very old and dry and light. I don't know what it was, but I called it "balsa" and 2 of us could load just over a cord of that in about 5 minutes. 15 or 20 minutes is more average. Of course the saved time was lost in stopping to build steam, because it had no heat when it burned so fast.
Cindy