Get Best Results by Seasoning Dense Wood Species
You will get the best results and more heat per wood volume when burning the highest density (heaviest) wood you can find. Dense firewood will produce the highest recoverable BTUs, but all wood must be "seasoned" for best results. Seasoning lowers the moisture content so less energy is used to drive off water (which limits heat efficiency).
Many of these heavy woods have excellent burning properties during the three stages wood goes through when burned. The final "coaling" stage is very important for sustaining heat over time. All of the best, and usually hardest and heaviest, wood species have excellent coaling properties as they continue burning after the initial moisture and all gasses are driven off.
Use Denser Wood to Increase Heat Production
Trees considered to be deciduous (lose their leaves in winter) and, more specifically, hardwoods tend to be a more dense wood and will burn hotter and longer than trees considered to be evergreen or softwood (there are some exceptions). Firewood will also burn hotter if seasoned under a shelter to reduce the moisture that drives off heating as wood burns.
Wood heat value is measured in BTUs or British Thermal Units. The higher the BTU value, the more heat you get per unit of wood. Heating value is based on density, weight, BTUs, and coaling ability.
Next, we'll discuss the best and worst tree species to use for firewood ranked by their total ability to establish and retain heat:
Five Best Firewood Tree Species
- Hickory: 25 to 28 million BTUs/cord - density 37 to 58 lbs./cu.ft.
- Oak: 24 to 28 million BTUs/cord - density 37 to 58 lbs./cu.ft.
- Black Locust: 27 million BTUs/cord - density 43 lbs./cu.ft.
- Beech: 24 to 27 million BTUs/cord - density 32 to 56 lbs./cu.ft.
- White Ash: 24 million BTUs/cord - density 43 lbs./cu.ft.
Five Worst Firewood Tree Species
- White Pine: 15 million BTUs/cord - density 22 to 31 lbs./cu.ft.
- Cottonwood/Willow: 16 million BTUs/cord - density 24 to 37 lbs./cu.ft.
- Basswood: 14 million BTUs/cord - density 20 to 37 lbs./cu.ft.
- Aspen: 15 million BTUs/cord - density 26 lbs./cu.ft.
- Yellow Poplar: 18 mm million BTUs/cord - density 22 to 31 lbs./cu.ft.