How Long Do Kiln Dried Logs Last?
There is something unique about burning wood for heating. Perhaps it is the natural feeling of being back to our caveman roots 1000s of years ago that makes heating by firewood so comforting. Firewood has been used as a source of heating for 1000s of years so it’s no wonder that 200,000 wood burners are being installed each and every year in the UK.
But one of the things we get asked most frequently at Firewood Farm is about how long do our kiln dried logs last? Or, do they simply burn too quickly to be of much use for cheap and efficient heating. Are kiln dried logs an expensive commodity to make rooms cozy or can they actually be used to reduce heating bills.
The key to this is to look at how long an average kiln dried log burns for. Sadly though, the answer is never quite as simple as the answer depends on a number of factors:
The Type of Stove
This is perhaps the single most important factor when determining how efficient heating your room and home using firewood is. An open fire will consume much more wood or other smokeless fuels than that of a modern, enclosed fire. Open fires only tend to be around 20% efficient for heat, meaning most of the heat is wasted in combustion or it escapes through the chimney. Modern stoves with properly fitted flues are over 80% efficient. Meaning you could save up tot 4x the number of logs when using a modern stone Vs an open fire.
The Type of Wood
The type of wood used will play an instrumental role in how long the average kiln dried log burns for. Firstly, hardwood logs should always be used other than when starting a fire. Hard wood is much denser than soft wood like pine so will burn for much longer.
However, there are also many different types of hardwood that can also play a role in how long each log will last. Oak logs for example are extremely dense and will burn for longer than slightly softer hard wood. The average oak log for example will burn for between 2-3 hours depending on the fire, moisture content and the size of the log. Whereas silver birch logs which is less dense will only burn for 90 minutes to two hours.
The density of the wood plays a major role in both the heat output and burn length. For example, European Ash has an average density of 0.71 (103 kg/m3) compared to oak which can go all the way up to 0.9 but tends to average out at 0.75 (103 kg/m3).
Moisture Content of the Wood
The moisture content of the kiln dried logs is also an important factor in determining how long the average kiln dried log will burn for. The water content effects the heat output, the amount of sot and the overall burning time. In general terms, the higher the moisture content, the longer the wood will burn for but will produce far less heat and is therefore an extremely inefficient way of heating a home. Although ‘wet’ wood will cost less than properly kiln dried logs, it should be noted that all kiln dried logs sold in the UK must be now dried to under 20% moisture content. At Firewood Farm for example, all of our logs conforms to the ‘ready to burn’ standard. Not only does a lower moisture content mean a better value fire, it also means your fire will need less maintenance as it will produce less sot which can line the flue and chimney.
So there we have it! The amount of time the average kiln dried log will burn for will depend on a number of factors such as the moisture content and the type of wood but you can typically expect most kiln dried hard wood logs to last for at least 90 minutes.