Sustainable Heating Solutions

Woodchip boilers

Woodchip boilers are generally better suited to larger installations, or where a customer has a ready timber supply that they wish to utilise to fuel their new boiler. Woodchips are easy to produce, and almost as easy to handle and distribute as pellets. They are a cheaper fuel than pellets, but you do require a greater volume of woodchip than pellets to achieve the same thermal output as they have a lower energy density.

Woodchip boilers offer identical levels of sophistication and automation as their pellet-burning counterparts, however, because woodchip has a lower energy density than pellet, woodchip boilers do require a larger fuel store, or more frequent refilling. Delivery systems for woodchip are less sophisticated than those for pellets as chip does not ‘flow’ in the same way that pellets do – so careful consideration has to be given to the location of, and access to, woodchip fuel stores.

A typical woodchip-fuelled system comprises a boiler, accumulator tank, controls and a fuel store containing some sort of mechanical device to move the chips to the feed auger, at this small scale this is usually a sprung steel stirrer. The chips are then conveyed to the boiler by the auger completely automatically. The larger the fuel store, the less reloading is involved and a fully automated system like this would need a fuel store of preferably at least twice the size of the delivery vehicle to ensure the supplier can deliver full loads.

If you plan to chip your own fuel on-site, some of these considerations will become less important.

To learn more about biomass, please go to the biomass page in our Sustainable heating technologies explained section.

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