The commonly available and most suitable hard wood types are Ash, Beech, Birch, Blackthorn, Elm, Hawthorn, Hazel, Hornbeam, Maple, Oak, Rowan, Sycamore, Wild Cherry, Willow, Alder, Apple, Pear, Holly.
Wood is divided into two main categories, hard and soft. A rule of thumb is that around twice as many softwood logs as hardwood logs may be required to achieve the same heat output. Softwoods, (conifers) include spruce and pine, burn much faster than hardwoods and have a tendency to spit and crackle. Freshly harvested wood contains a naturally high amount of water, between 65-90% depending on the species. Removing the water is known as seasoning. This term suggests a period of time, and for natural air drying up to two years is recommended. The more efficient a fire burns, the less fuel is required and less flammable tar is deposited.
It is important that logs should be dried and stored under cover for a minimum of a year to get the moisture content down; this releases more heat energy per log into the room and reduces the amount of creosote and tar deposits in the chimney. The correct fuel uses only well- seasoned wood with a moisture content <25%.