How to get the most out of your firewood, and how to know if it is ready to burn.
Most woods – split and stacked outdoors in the sun and wind – season completely in six to eight months. Wood is generally considered seasoned, and ready for use as firewood if its moisture content is 20% or less.
A moisture meter will accurately measure the moisture content of your wood. But you can roughly check the dryness of your wood without a moisture meter by knocking two pieces together. If you hear a sharp high pitch sound, the wood is probably dry. If you hear a dull thud, the wood is not fully seasoned.
Check for cracking on the ends of firewood as this also indicates that the wood is seasoned and dry.
Firewood that is dry and seasoned can be stored indoors or outdoors. If you are storing wood outdoors, it is best to cover the top part of the pile with a tarp to keep it dry. For the most part, it is not advisable to store wet, unseasoned wood inside because of the problems dealing with all the moisture in the form of water vapour that will be released from the wood as it is drying.
Up to half the weight of freshly cut logs is water. After proper seasoning only about 20% of the weight is water. As the wood is heated in the firebox, this water boils off, consuming heat energy in the process.
The wetter the wood, the more heat energy is consumed. That is why wet wood hisses and sizzles while seasoned wood ignites and burns easily.
Smoke (or flame)
As the wood heats up above the boiling point of water, it starts to smoke. The gases and tar droplets that make up the smoke are combustible and will burn if the temperature is high enough and oxygen is present. When the smoke burns, it makes the bright flames that are characteristic of wood combustion. If the smoke does not burn in the firebox, it may condense in the chimney, forming creosote (the sticky tar like substance that clings to inside of chimneys and flue pipes reducing their ability to draw)
As the fire progresses and most of the smoke and tars have vaporized, charcoal remains. Charcoal is almost all carbon and burns with very little flame or smoke. It is a good fuel that burns easily and cleanly when enough oxygen is present.
Of the total energy content of the wood you burn, about half is in the form of smoke, and half is charcoal.