Wood Pellet/Chip Boilers

There are many reasons for using a wood pellet/wood chip boiler to heat a building. Apart from the fact that such systems are eco-friendly and have proven themselves in technical terms, they constitute an economically viable solution. Nowadays modern wood heating systems operate just as well as convential oil or gas systems and have efficiences in excess of 90% . The system operates in exactly the same way as a conventional system with the exception of the fuel delivery. Pellets and chips are feed through an auger which is automatically controlled by the boiler. The frequency/quantity of fuel and the Kw output are all controlled by the boiler interface. As fuel enters the boiler the fire is ignited either by elements or an electric blower (depending on boiler model).

Benefits:

• Carbon Neutral - extremely low carbon emissions.
• High efficiency.
• Advanced control package.
• Reduced fuel costs.

Properties of Pellets and Wood Chips.

Wood pellet is primarily used for domestic installations as they are a more standardised fuel that can be more easily handled and delivered. Pellet supply can either be in small 10kg bags or in bulk deliveries of 3 tonne. With bulk deliveres the customers involvement is non-existent as the pellets are blown into the store automatically. (Example fuel stores can be found in our download centre and fuel suppliers).

Pellets are a standardised fuel that are made by pressing dry shavings or saw dust. The production process does not use chemical additives - only high pressure and steam. Depending on the moisture content. the energy content of pellets lies between 4.7 - 4.9 kWh/kg - 2 kilos of pellets therefore have a slightly lower calorific value than a litre of 28sec kerosene (10.18 kWh)

Wood Chips are only used in large commercial installations because of the high moisture content and non-standard composition. The woodchips are small peces of wood that are 5 - 50mm long (measured in the direction of the fibre). There may also be some longer twigs and finer material among them. The quality of the chip depends on the raw material and the chipping process.

Two sources of chips are available:

1. Chips from the sawmill industry: should have a maximum water content of 30% and be of uniform quality and size.
2. Forest Chips: Given their water content of between to 40 to 60%.

Technical Properties:

Pellets or Woodchips?

Pellets and woodchips have various advantages and disadvantages that have to be considered. Primarily wood pellets are always used for domestic installations as most manufacturers only produce boilers to burn pellets and the fuel store arrangement is less expensive. It is only in commercial applications that wood chips are considered. Which fuel is used will depend very much on local conditions.

Advantages/Disadvantages of Wood chips and Pellets: