Wood pellets are a form of combustion fuel that is clean-burning, convenient and cost-effective. They are made from natural wood residues, which are dried and compressed.
The wood pellet industry is relatively new to New Zealand, but is fast gaining popularity. The first pellet mill was established in Canterbury, nearly a decade ago, and there are now five pellet mills throughout New Zealand.
The wood pellet industry is well established in Europe and North America. Today over 1.2 million pellet fires are in use throughout North America.
Wood pellets are produced using waste material such as untreated sawdust and shavings from local sawmills. This woody material is dried to less than 10% moisture content and compressed into 6mm pellets, under high pressures and temperatures. This process solidifies the pellet, utilising the natural lignin found in wood.
Wood pellets are a highly standardised and compact fuel, allowing cost-efficient transportation and storage.
The design of pellet stoves ensures almost complete combustion, resulting in the cleanest burn and lowest ash of any solid fuel. Minimal emissions mean there is a very low impact on air quality.
Wood pellets can be burned in specially designed fires and boilers, which are very efficient heating appliances. They come in a range of sizes and styles, and are suitable for both domestic and commercial applications.
Pellet fires heat up quickly and the temperature can easily be adjusted by controlling the rate of fuel going into the firebox.
Wood pellets will burn in traditional wood burners, but it is not efficient or cost effective, and is not recommended. It is far better to install burners that are designed for pellet fuels. The exiting chimney can be used for venting the flue system of a newly installed pellet burner.
Wood pellet fires designed for home heating are available as either free-standing or fireplace insert models. Because they burn so efficiently, a number of different fluing options are possible – either vertically through the roof, or horizontally through an outside wall. The key to installation is placing the stove near an electrical outlet.
To operate the fireplace, wood pellets are poured into a hopper and then automatically fed into the firebox. An electric element lights the wood pellets. Most models have a push-button start and begin heating straight away. Heat output is controlled by a thermostat, which regulates how many pellets are fed into the firebox.
Wood pellet boilers are recommended for larger buildings and industrial applications. Based on the same principle as other industrial boilers, the combustion chamber is enclosed by a water jacket. This water is them used as a heat transfer medium.
The are several ways to distribute the heat, including radiator systems, underfloor, or forced-air central heating.
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