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Log about to be put in burner


Log-fired heating conjures up images of open fires and log stoves,

but nowadays sophisticated, controllable log boilers are available to provide central heating and hot water.

Logs are ideal for domestic and community buildings using stoves or boilers with an output of up to 70-80 kW. Larger boilers require a considerable amount of man hours for stoking. Stoves require frequent manual stoking whereas boilers, particularly large ones, only need to be fuelled once or twice a day.

Logs sizes required by boilers and stoves range from 15 cm to 50 cm. Their width should be between 6 cm and 8 cm. Use consistent log sizes to achieve uniform burning at an even rate. Logs should be seasoned by the supplier for one or two years prior to sale.

It is advisable to buy logs by volume rather than weight, since moisture content (and therefore weight of water within the logs) can vary.

As hardwood species are generally denser than softwood species, a tonne of hardwood logs will occupy a smaller space than a tonne of softwood logs. Dense woods tend to burn for a longer period of time than softwood meaning fewer 'top ups' are required to keep a log stove burning for a given length of time. If you measure wood by volume you will receive more kilo-Watt hours (kWh) of heat from a cubic metre (m3) of hardwood than softwood, though this will tend to be offset to some extent by the higher calorific value of many softwoods.