Firewood Recycling


BTU (British Thermal Unit) is a measure of heat, which is a form of energy. It was originally defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. This is the standard measurement used to calculate the amount of energy that a fuel, such as wood, has, as well as the amount of output of any heat generating device.

The Wood In Firewood:

All firewood is not created equal. While it is true that the energy content of a pound of wood. (dry – zero percent moisture no matter the type, is about the same (8,600 Btu’s)). The density of wood makes its wood burning quality quite different. 

The moisture content in firewood also affects its quality of burning. Burning green wood not only produces more creosote (distillation of tar from wood or coal and is used as a wood preservative) but is less efficient because it must remove the water. Any moisture in the wood reduces the heat directed to the home by carrying heat up the chimney during vaporization. 

On top of that, the efficiency of the wood burning appliance also contributes to the quality and effectiveness of the wood burned. 

When all other factors are equal, a denser wood will produce more Btu’s. Dense dry wood produces the most heat.

How Wood Burns:

When wood burns, three things happen:   

1. Water is removed by vaporization.  

 2. Chemically, the wood breaks down into charcoal, gas and volatile liquids, where carbon dioxide and water are the basic end products.  

 3. The charcoal burns, forming carbon dioxide either directly or with an intermediate conversion to carbon monoxide.

Each pound of water vaporized uses about 1,200 Btu. A pound of wood with a 20% moisture content contains 0.17 pound of water and 0.83 pound of completely dry wood, having a heat value of 7,000 Btu.

Why is this important ?:

When building a fire the purpose of the fire can determine the type of wood that you use. For instance, using something that is solid and burns very hot is ideal when using it for heating a house. When using it for cooking, you would want to choose your type of wood based on what you are cooking, how fast you are cooking, how much or what flavor you are wanting to permeate.

Below is a BTU chart. This will help you see the different types of wood that are in our hardwood, fruit wood mix, and how hot they burn.

Have more questions about our firewood options or would like to place an order? Call our office (303) 868-3164 or visit our Recycling page for more information or pricing.