Wood stoves and ranges are available with outputs
from 5 to 20kW and can be used to heat a single room or domestic
hot water and central heating.
Important: before purchasing any equipment,
read Managing a successful wood fuel
installation and get expert advice.
A back-up system
Many people in the more remote parts of Scotland need heating
that will operate during a power cut. Wood burning stoves and
ranges can provide this.
It is possible to have domestic hot water as well, as long as
the system is fed by gravity, rather than by electric pump. A
pumped central heating system will, of course, not work in a power
cut. Indeed, a fully pumped system should not be fired during a
power cut as there would be a risk of boiling the water which
cannot circulate.
Types of wood stove
Log stoves
Log stoves are often the cheapest option, particularly if you
have access to your own log supply. Many are available with a
multi-fuel option and can burn both logs and solid fuel, though it
is not advisable to burn wood and coal at the same time.
Larger wood burning stoves can provide enough heat to run up to
a dozen radiators, but will require frequent manual re-fuelling.
These stoves are plumbed into a pumped central heating circuit
which can be controlled by thermostats.
If the stove is used to heat water in an accumulator tank, the
wood can be burnt more efficiently and the heat delivered to a
central heating system in a much more controlled way - in this case
the stove may need to be fired only once or twice each day.
Wood pellet stoves
Pellets burn very efficiently and require much less manual
handling than logs.
Pellet stoves burn in a similar way to log burners. With a back
boiler they can provide convenient hot water and central heating.
Most stoves have a built-in hopper which can hold enough pellets
for several days.
Pellet stoves are much easier to regulate than log stoves, and
can be left to burn all day with minimal attendance. They are
filled by hand using bags of pellets of 15kg upwards.
The flues for pellet stoves are sometimes smaller diameter than
for traditional wood and multi-fuel stoves, making them more
unobtrusive and installation easier.
A pellet stove consists of a hopper to store the pellets, a
screw feed mechanism to transfer the pellets into the combustion
chamber, electronic controls and electric fans to deliver the
combustion air and distribute the heat.
The heat output is thermostatically controlled by regulating the
flow of pellets into the combustion chamber. The stoves are ignited
electronically and the ash falls into an ash pan at the base of the
stove. Because of the high efficiency combustion the ash pan may
only need to be emptied every two months.
The number of suppliers of wood pellets is increasing and you
should be able to get them delivered in your area.
Range stoves
It is still possible to buy ranges that can be fuelled by wood.
Esse, Rayburn, Stanley and Thornhill sell models that can be used
for cooking only, cooking and domestic hot water or cooking, hot
water and central heating. The Thornhill Range Cookers run on
pellets using a patented burning system to ensure high
efficiencies.
With the exception of the Esse and Thornhill Range cookers,
these ranges were primarily designed to burn coal and solid fuel,
and therefore burn wood less efficiently. However, they still work
well with dry logs.
More information and technical details can be found by
contacting the manufacturers.
Tile or ceramic stoves
Ceramic stoves are wood burning stoves which are made of fired
clay blocks or from carved soapstone. They are quite large
structures and can extend to ceiling height. The internal flueways
are very long and this leads to complete combustion of all the
gases from the wood. The ceramic blocks store heat and the stoves
require firing only once each day.
Because of their size, ceramic stoves are best suited to
new-build situations and can sometimes prove difficult to retro-fit
into existing houses.
Maintenance
Stoves require regular de-ashing but a bed of embers on which to
set a fire should be left.
Providing the stove has been installed and is operated within
the manufacturer's guidelines, and wood burned is within the
specification provided by the manufacturer, the only regular
maintenance required will be thorough cleaning of the flueways,
appliance flue connector pipe and the chimney.
Publication to download
The Biomass Energy Centre have produced a useful guide which
includes wood burning stoves:
Biomass Heating: a guide to small log and wood pellet systems
[PDF]