A log burner is one of the best additions you can add to a home, if you ask me. The gentle glow of a fire, the cosy winter evenings, and the excuse to chop and stack firewood in the garden are all brilliant. But how much wood do you need to split, store, and burn to warm your house up efficiently?
The Triangle of Fire
It’s not the name of the next big blockbuster film, but the three things that make, or break, a fire. Imagine your triangle of fire as a house of cards. If you take one of them away, the whole thing will collapse. Understand the triangle and you’ll always stay warm.
The three elements that need to work together to start a cosy fire in your wood burner are:
This is the stuff that burns. Whether it’s paper, petrol, wood, or cloth- if it can burn, it’s fuel. When it comes to wood burners, you need a decent pile of well-seasoned firewood.
A fire needs oxygen to keep burning. If you have ever put out a candle with a snuffer, you’ll understand this process. A fire that is starved of oxygen will go out pretty quickly.
This is what starts the fire. A good old box of matches, a discarded cigarette, or the sun’s rays are all sources of heat that can start a fire. Without some form of heat, your fire will remain unlit.
What Makes Good Fuel?
You know that you need fuel to keep a fire burning, but what’s the difference between good fuel and bad fuel? When it comes to wood, the species of wood and the moisture content inside it are the most important factors.
The two types of wood that you can use for burning are softwoods and hardwoods. Hardwoods are better for burning than softwoods because they’re denser and have more potential energy stored within them.
Properly seasoned hard woods like ash, oak, and beech are the absolute best woods you can burn in your stove. Softwoods light easier, which makes them ideal for kindling, but unless you like refuelling your stove every couple of hours, stick to hardwoods.
Are there any types of wood to avoid putting on your log burner though? Resinous softwoods like pine are considered “bad fuels” because they produce toxic creosote when they burn. This can coat the inside of your flue and lead to dangerous chimney fires as well.
Wet wood is hard to light and harder to keep lit. Get yourself a moisture meter and test out the wood that you have. It really needs to be under 20% moisture content to burn cleanly and efficiently. Well-seasoned firewood is essential to get the most out of your wood burner.
How Much Oxygen Do I Need?
The second pillar in the fire triangle is oxygen. Too much, and your fire will burn too quickly, not enough, and your fire will peter out. Wood burners come in all shapes and sizes, but they should all include a way to adjust the air flow.
Most modern log burners will have primary and secondary air flow controls. Found on the bottom and top of the burner, the primary control adjusts the air that flows into the base of the fire, and the secondary control controls the flow of air to the top of the fire. You might also find an air flow control on the flue above your wood stove.
If you have a glass front on your log burner, it’s easy to see how each of these vents control the size of flames inside. As a rule of thumb, I like to open both vents wide when starting a fire, then close them down once the fire has produced white coals. Closing the vents will make your fire last for as long as possible.
Can You Feel the Heat?
The heat side of the fire triangle is most important when you’re starting your fire. It’s important to have enough tinder to start the fire and kindling to build it up. I don’t like using firelighters or other chemicals in my stove, so I use “cigars” of tightly rolled up newspaper to light the fire, then thin pieces of softwood as kindling. Once the fire has built up enough, it’s time to add the hardwood fuel.
How Long Should a Log Last then?
As we’ve discovered, there are at least three factors that will contribute to how long your logs will last on your fire. The quality of your fuel and how well seasoned it is, the amount of oxygen that can get to the fire, and the heat source in the first place.
You also need to check the condition of your flue. If you’ve burned a lot of wet or resinous wood in your stove, there might be a lot of sooty deposits left on the inside of your chimney. These are dangerous because they can catch fire, but they also restrict the air flow and lead to a poor fire in your stove.
Get your chimney or flue swept before the wood burning season starts. A well maintained flue will result in a cleaner and much more efficient burn that will get the most out of your firewood. If you use your wood burner to heat your house, you might need to get it swept more often.
A well maintained log burner stacked with quality seasoned and well split hardwood, with the vents fine-tuned to restrict airflow will burn overnight.
It takes a bit of practise, and it requires stacking the firewood inside your stove tightly to control the airflow, but it’s possible.
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So, remember, dry hardwood fuel, well controlled air flow, and a clean flue are the three biggest factors that will get the most bang for your firewood buck. Get it right, and you’ll enjoy a long winter of efficient fuel use and a cosy home too.