Burning properties of wood

Things to consider

There are a number of factors to consider when buying firewood and working out how much to buy. We have listed a few key points to consider when choosing what wood to buy from us. 

Is a fireplace your only form of heating?

If so you will need more wood than a house that also uses a heat pump

What size is the room or house that you are heating?

A larger space will need more wood to heat it - take into account the height of the ceilings as well. 

How large is your firebox?
This will dictate the size of the firewood you can burn, we cut all our wood to approx. 300mm in length so it fits all modern fireplaces.

How well insulated is your house?

A well-insulated house and double glazed windows help to retain the heat, meaning you should require less wood to heat your home.

Do you have an open fire or is it enclosed?

An open fire will lose a lot of heat straight up the chimney (as much as 70%) so you will need to burn more wood to get the same warmth as you would from a log burner. Also, there are certain woods to stay away from on open fires as they can spit and spark which can damage the floor around the fire and is a fire risk. 

How long will you be burning your fire for each day?

If you are burning your fire for long periods of time (most of the day) then you will want more hardwood as this puts out more heat than softwood and burns for longer (so no topping up the fire every 30 minutes). If you are only burning the fire in the evenings (or just a few hours a day) you will want to look at our Inferno Mix – this is a 50/50 mix of hard to softwood.

 

The different types of firewood

Different types of firewood? but wood is wood, right? Wrong, not all wood was created equal! There are two main types of wood, softwood, and hardwood. 

Softwood 

• Is fast-growing and has a lower density 
• Has a lesser ratio of heartwood to sapwood than hardwoods - heartwood gives more heat than sapwood when burnt
• Lower density woods are easier to light and start a fire with. It also is easier to split and lighter to handle
• Burns quicker than hardwood and don't give off as much heat
• Seasons quicker than hardwood but is more prone to taking moisture back on once dry

Hardwood

• Takes longer to grow than softwood
• Has a higher density 
• Burns for longer and puts out more heat
• Takes longer to season but has more moisture resistance than softwoods
• Has a higher ratio of heartwood than softwoods
• Heavier and harder to split than softwoods

 

Name	Type	Sparky	Burn Time	Burn Temp	Ideal Use
Pine	Softwood	No	Quick	Warm	Open fires/Starting a fire
Oregon	Softwood	A Little	Medium	Warm/Hot	Starting a fire and normal burning
Larch	Softwood	Yes	Medium/Long	Hot	Normal burning
Macrocarpa	Hardwood	Yes	Long	Hot	long periods of burning
Blue Gum	Hardwood	No	Very Long	Very Hot	Long periods of burning and high heat
Beech	Hardwood	No	Very long	Very Hot	Long periods of burning and high heat

 

So what should I buy?

The average household during an average winter in Dunedin will use between 6-10 cubic meters of wood. We recommend burning hardwood as much as possible as this gives you more heat per log meaning you don't need to buy as much wood, you don't need to stack as much wood, and also you won't be topping the fire up every 10 minutes as it burns slower, so fewer trips to the woodpile on those cold winter nights. 

For a household that burns the fire most of the day a good ratio of hard/softwood (burning wood and starter wood) is 80/20 respectively. If you only burn your fire a few hours a day then you will want closer to a 50/50 mix of wood.

 

 

Perhaps you've been told the same thing: don't burn pine in your fireplace or wood stove. Many believe it, and even supposed "professionals" perpetuate the statement, or fail to explain the reason. The common explanation is that pine creates a dangerous soot buildup in the chimney, called creosote. While true, it's not entirely accurate. Pine does have a place in your wood stove or even your fireplace.

The Truth

The reality is, your firewood supply may -- and should -- contain a mixture of both hardwoods such as gum and macrocapa along with softwoods such as plantation pine. Dense hardwoods burn longer and produce more heat, making them superior to softwoods for maintaining your fire. However, softwoods like pine ignite easier and produce a hotter flame since they burn more rapidly. This makes pine an excellent choice for getting your fire started and as a fast source of heat. Even use it for keeping the fire going if it's all you have, or if you want a hot fire with lots of flames.

All Wood Creates Creosote

Pine creates creosote. In fact, all wood does. But opponents of burning pine believe that it creates more creosote merely because it contains a lot of pitch. On the contrary, hardwoods can actually cause more creosote than softwoods like pine, Creosote is nothing more than a condensation of small, unburned particles contained in the smoke that coats the chimney surface as it exits. Similar to a hot shower, when the heated particles contact the cooler flue, the vapor solidifies into a layer of creosote. Since softwoods produce a hotter fire, the smoke travels faster, allowing less time for condensation. Hardwoods, on the other hand, burn slower and lower. When hardwood smoulders, the smoke rises less quickly. It lingers longer inside the chimney, creating more condensate.

Avoiding Creosote

Since pine works well for kindling and for romantic fires with high flames, and given that hardwoods create more creosote, it's unavoidable that you will accumulate creosote. You can reduce the amount of creosote by purchasing properly seasoned firewood. When your firewood is dry -- about 20-percent moisture or aged at least six to 12 months months, it will burn more efficiently, creating less creosote. Green, wet wood smoulders, creating more creosote-producing smoke which represents nothing more than energy literally going up in smoke. Burning a hotter fire and using smaller logs -- no matter what firewood you use -- also helps avoid excessive creosote. In addition, don't burn treated pine lumber nor any other piece of trash.

Signs of Creosote Buildup

Creosote is highly flammable and can lead to house fires. Always watch for signs of build-up including dark, smelly smoke or soot on the furniture. Smoke filling the home is another danger sign, as is internal temperatures below 300-degrees Fahrenheit for a wood stove. Clean your chimney at least once a year -- more often for heavy use -- to remove inevitable accumulation and burn pine and other wood safely.