Rules of thumb in case anyone reading doesn't know these. Softwoods (conifers, evergreens) contain less heating value than hardwoods. When they are dry, they burn hot and fast and they gum up stacks (ash mixed with resin) much faster than hardwoods. They also have more irritating and corrosive smoke and they can impart a flavor (that some people really like) to syrup if the smoke gets into the pan. As long as you are prepared for the differences, you can use it as firewood, even inside your house, but that is not advisable because of the higher chimney fire potential. Some hardwoods (birch, aspen, alder) are much like softwoods. Ash wood burns very hot when dry. Other hardwoods, (fruit trees, nut trees, oak, maple, elm) burn cooler and longer, even when dry, and should be split in smaller chunks if a really hot fire is required.