For the best heat output it’s important to always buy wood that is as dry as possible and produced from a good quality hardwood species. You should always buy firewood by volume and not by the ‘load’ or by weight, as this will help you compare prices and ensure you receive the amount that you ordered.
Moisture Content (MC)
The moisture content has the biggest effect on the amount of heat that your fire will produce.
When trees are felled they typically have a water content of 50% or more. If you burn wet timber much of the energy locked up within the timber will be used to dry the wood and produce steam, rather than heating your room. Typically you will need to burn 3 logs with a moisture content of 50% to get the same heat output as burning 1 log with a moisture content of 20%. The density of wood also has an effect on the amount of energy contained and therefore the heat output produced.
Hardwood species like ash and oak tend to grow more slowly than softwoods like pine and therefore have more energy contained within them for the same volume. This means that if you burn hardwood instead of softwood you will use less logs for the same heat output. Typically you will need to burn 4 softwood logs to produce the same heat output as 3 hardwood logs, assuming the same moisture content.We recommend that you always buy firewood by volume as this means that you can easily compare prices and ensure that you get exactly the quantity of logs that you ordered.
If you do buy by the ‘load’ always ask what the volume of the delivery truck is and never buy by weight as the wetter the wood the heavier it will be.Typically a log with a moisture content of 50% will weigh 3 times as much as one with a moisture content of 20%, assuming both have the same volume. Seasoned won’t give you quite the same heat output as kiln dried, but it does make a good lower cost option for all open fires, stoves and log burners.
The low moisture content of kiln dried ensures that it is easier to light, produces more heat, burns cleaner and more efficiently, meaning you use less to produce the same heat output as traditionally seasoned firewood.