Log Boilers

Log boilers cost the least from an installation perspective, as there is no feed mechanism required for the fuel - you have to feed the fuel in yourself!

The main consideration for logs is the source - you don’t want to run out. You can buy in logs, but the type of wood (hard/soft) and water content will vary - so if possible you want to have your own managed woodland. As a guide if you were using 12,000 litres of oil then you would want a 120kW log boiler which would consume around 96m3 of stacked, split logs per year.

This also highlights the need for sufficient storage space - you will need enough space for this heating season, and the next.

With a log boiler, you ideally only want to fire this once a day - you do not want to have to keep feeding logs in all day. This means that you need a greater amount of thermal storage than you would for a pellet or chip boiler. And that the boiler will need to be a bigger size too - so that it can generate more heat in one go.

Waste Wood

It is possible to burn waste wood in a log boiler without issue, but it is important to consider the amount of additional chemicals that may be present - so chopped up pallets should be fine (the nails will drop through with the ash), but you do not want to use waste wood which has been coated with paint or other chemicals - this could damage the internals of the boiler and cause noxious emissions.

	Water content	Heating value
Fresh from the forest	50-60%	2 kWh/kg
Stored over the summer	25-25%	3-4 kWh/kg
Stored over a few years	15-25%	4 kWh/kg

We offer log boilers from SOLARFOCUS who as well as a log-only boiler provide a log/pellet model and a log/chip model, so that you can use either fuel for the greatest convenience

Example layout of a log boiler with two thermal stores

Log Chip Pellet Biotech SOLARFOCUS

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