BASICS / BIOMASS BURNERS
Wood pellet boiler by Warmflow Grant Spira, grantengineering.ie
BASICS
Biomass burners Biomass is organic matter used as a fuel. It covers everything from fish oil and bone meal to wood and energy crops; for your home it’s likely to mean a log, wood chip or a wood pellet burning boiler or stove as other fuel sources are not yet feasible on a small scale. Words: Tony Traill
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lmost everyone is accustomed to burning wood or peat on an open fire to produce heat. In its most basic form this is biomass combustion. We all know that it takes time to light a fire, for it to become established, to burn well and to produce good heat. To do this it needs a regular supply of good quality, dry wood and adequate air for combustion. If the wood is too damp or the draught is insufficient it will not burn well. Alternatively, if there is too much draught all the heat goes up the chimney! Similarly, once you stop 108 / SELFBUILD / WINTER 2018
fuelling a fire, it takes time for the fire to die down and eventually go out. These are the basic principles applicable to all biomass combustion and should be borne in mind when designing any system.
Sizing an installation
The regulations are many and complex so professional input is necessary; in both NI and ROI a HETAS registered installer will ensure safe installation. Also make sure the equipment and final installation is CE marked. There is no infallible rule of thumb for sizing but generally the start point is to calculate the heat losses from that room and ensure
How long does timber take to dry? Before you can use it as fuel, you’ll have to wait 18 to 24 months for your recently cut timber to dry in a well ventilated shed.
that the heat output from the appliance to the room (normally quoted in kW by the supplier) does not exceed the calculated heat losses. Any design of stove/cooker will heat the room in which it is located and, if the heat output to the room is too high, the room will become unusable when the appliance is in operation. Room heat loss calculators are available online for rough calculations, but, for modern houses, accurate heat and ventilation losses should be established by a professional. A stove with back boiler may need to dump heat and it may be possible to include a thermal store