Biomass boilers & wood stoves
Log fired boilers are a logical step up from stoves. They range from systems designed for hot air space heating to be used in workshops, run on off-cuts, to boilers designed to run domestic heating and hot water. While some systems are at the basic, simple end of the market, employing robust, reliable technology, some boiler systems are highly efficient, with sophisticated controllers offering the option of zoned heating.
Stoves are a widely available, simple technology. They are considerably more fuel efficient than open fires, and can be found in a wide variety of different shapes, sizes and designs. If you are keen to heat your house with wood fuel on a limited budget this is probably the cheapest option. Even if you only use a stove instead of your normal heating method for two weeks at either end of your heating season, you are still making an important contribution.
Pellet boilers produce hot water for central heating systems. They are available for every heating requirement – from 5kWth for low energy houses up to 5,000kWth for large building complexes or industrial process heat. Pellet boilers operate with automatic feeding systems that bring in fuel from a storage room and require very little maintenance. A pellet boiler is an excellent replacement for an oil heating system.
Pellet stoves are automatic heating devices for heating individual rooms or flats. Pellets are filled into a storage space within the stove. From there they are fed automatically and ignited electrically. Pellet stoves burn with very low emissions and excellent efficiency of up to 90%. They either produce hot air that heats the room directly or hot water for central heating, taps, baths and showers.
Pellet Storage and Handling
We strongly recommend that when installing a pellet storage, the UK Pellet Council’s guidelines are followed.
Wood chip boilers are appropriate for medium and large scale installations. Buildings that currently use wood chip boilers include blocks of flats, visitors’ centres, office buildings and even airport terminals. It is very important to ensure that wood chip boilers are supplied with the appropriate type of fuel. This will vary between boiler types and sizes. The two most important variables are particle size and moisture content. Wood chips that are too large or too wet, for example, can jam the fuel feed system, reduce the efficiency and reliability of the boiler or cause the control system to trip out. More information about fuel standards can be found here.
District heating is the use of a centralized boiler installation to provide heat for a number of buildings. This can use a heat only boiler, or the heat from a combined heat and power (CHP) plant.
Wood fuel boilers tend to be physically larger and more expensive than equivalent gas or oil boilers. This is partly as a result of the physical requirements for fuel transportation and a high temperature combustion environment. As boilers get larger the disparity with gas and oil boilers becomes comparatively smaller, and so wood fuel becomes more economically attractive, especially for installations of the scale of a few hundred kWth.
District heating makes use of these cost advantages, as well as the administrative benefits of using a single boiler installation to provide heat to a number of buildings. These might be a number of individual houses, blocks of social housing, local council offices, a school, etc.
District heating is much more common in some European countries than in the UK. In Denmark, for instance, district heating provides around 60% of all heating. Although the UK lags behind, there are already a number of successful district heating schemes in the UK, both using fossil fuels and biomass.