How does wood burn?

Operating a wood burning system effectively requires learned skills and practice.  While it's not that complicated - it is also not so easy either.  Simply taking a match and trying to light a log is unlikely to give you the glorious fires you see in the films.

A good starting point is understanding exactly how wood burns.  This process is divided into three wood combustion stages that all occur simultaneously:

 

1. Water Evaporation: A freshly cut log is nearly 50% water. This is why we suggest you buy either seasoned or kiln dried logs if you want an immediate fire. The process of seasoning and kiln drying reduces the water content of the log to less than 20%. What's the problem with water in your logs?  As the wood heats in your firebox the water boils off, consuming heat energy in the process. This means that you are using up your logs and heat energy just getting rid of the water. 10 kiln dried logs will generate the same level of heat as 33 unseasoned logs. This results in a hotter, more efficient fire using a 1/3 of the number of wood logs. Plus dryer logs ignite and burn more easily making the process of starting the fire much easier.

2. Wood Smoke: As the logs start to heat they produce smoke. The smoke comprises of combustible gases and tar droplets. You want the smoke to burn. This will happen if the temperature is high enough and there is enough combustible air supplied. Once the smoke starts to burn it will produce bright flames. If the smoke doesn't burn then it will flow into the chimney and either condense as creosote (bad for your chimney) or flow outside as air pollution (not good for the environment).  And worse - you've just wasted a large part of the heat energy produced by the logs you've purchased.

3. Glowing Charcoal: You want the charcoal to glow. Charcoal is a great fuel that burns easily and cleanly if provided with enough air.  As the fire progresses and the gases and tars vaporise, charcoal is left over and burns with a red glow and very little flame. One thing to remember with charcoal is that while it produces minimal smoke, the exhaust can have a high concentration of carbon monoxide so it must be completely vented outdoors.  We suggest you keep a carbon monoxide monitor / alarm in any rooms where you are operating fires.

The key to effectively burning wood is to boil off the water content quickly and make sure the smoke burns with bright flames before it leaves the firebox.