Wood
1 tonne of wood can save up to 400 litres of oil.
Wood should ideally be stored for 18 months under cover and exposed to the wind. This “seasoning” can also be completed in a much shorter time by drying. It is possible to dry wood using the Dragon which then makes your fuel much more efficient. We have alternative methods of drying, please ask for details.
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Moisture content. The moisture content of wood has by far the greatest effect on calorific value. Any water in the timber must be burned off as steam before the wood will burn. This will reduce the net energy released as useful heat. Logs that are not dry will result in a fire that smoulders and creates lots smoke and eventually tar. These tars can be corrosive, potentially damaging the lining of the flue and boiler and increasing the danger of a chimney fire. Well seasoned logs can have approximately twice the calorific value of green logs.
The effect of drying on calorific value This graph shows how significant moisture content is in determining the CV of wood. A fresh green log of about average moisture content has only around half the energy content of an equivalent, well seasoned log. The type of tree the log comes from can have some impact on the calorific value but it is usually extremely small. Most of the variation in calorific value between species is due to natural differences between moisture content in fresh cut logs (e.g. Ash has a particularly low moisture content when green).
Straw
It is possible to burn any type of straw in a Dragon Biomass Boiler.
Rape, linseed, bean, wheat, barley and miscanthus all burn whether rolled or in hesstons. When baling for the boiler, try to pack as loosely as possible. This allows air to get through the bale and therefore produces a cleaner more effective burn.
All straw should be stored under cover and allowed to dry in order to reduce the smoke emissions when the boiler is first fired from cold.
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The following boilers are eligible to burn straw under the Renewable Heat Incentive
Dragon D220 |
Round bales no more than 3’ 6” diameter |
Dragon D330 |
2 of round bales, no more than 3’ 6” diameter |
Dragon D240 |
One of round bale no more than 5’ diameter |
Dragon D370 |
Two of round bales no more than 5’ diameter |
Dragon D270 |
One of 4 x 4 x 4 square bale, or a 6’ round bale |
Dragon D370 (50) |
One of 8 x 4 x 4 bale or 2 of 6’ round bale |
All our other boilers are capable of burning straw of all types but are not eligible for the RHI.
Types of straw that are eligible are wheat, barley, rape, linseed, pea, bean and miscanthus.
Pallets and waste wood
Pallets should be un-treated and stored under-cover to keep them dry.
They can be loaded into the dragon using a forklift.
One 17 kg pallet will produce approx 60 kW of energy. Therefore a 240 kW D240 will burn for approx 3 hours when loaded with 12 pallets.
There are strict rules for burning waste wood in Dragon Biomass Boilers.
Please contact us for more information. Alternatively, go to the Environmental Agency web site and to your local authority. If you would like to burn waste wood in an approved appliance such as a Dragon, please contact us and we can advise on boilers that can burn full pallets or shredded wood.
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We have several ways of loading waste wood and arborcultural waste into a Dragon.
For example, our cartridge system involves loading a cartridge full of broken wood and loading it into the boiler with a forklift.