Modern log boilers can provide clean and efficient
heating to all domestic-sized situations and for heating larger
spaces such as village halls with a heat output need of up to 70-80
kW.
Larger boilers are available but require a
considerable amount of stoking.
Important: before purchasing any equipment,
read Managing a successful wood fuel
installation and get expert advice.
Log boilers need to be stoked only once or twice each day. They
operate at high levels of efficiency and have large combustion
chambers. Some boiler models can take large logs up to a metre
long, which reduces the work of sawing logs. Stoking should take no
more than five to ten minutes each day.
Heat is produced in a log boiler relatively quickly and is used
to heat water up to around 90 degrees C. The heated water is stored
in a highly insulated tank called an accumulator tank. This can be used to
deliver both central heating and domestic hot water to the house
for the rest of the day, in a programmable way.
The accumulator tank can be integrated into a system with
different heat sources. For example, the water could be pre-warmed
by solar panels, or come from other wood burning stoves or a
kitchen range, an electric immersion heater, or an oil fired boiler
which could also provide a back-up heating system.
Due to the fact that they require manual stoking, log
boilers may not be suitable for everyone, but for those who have
the resources and time they can be an ideal low cost
option, especially where potential end users have
their own source of fuel.
Combination log boilers
Some manufacturers incorporate automatic feed pellet burners
into their log boilers. These combine the best features of a
batch fed log burner and an automatic pellet burner, giving the
user considerable flexibility over the way in which the boiler is
operated, depending on the fuels available. A pellet fuel store or
silo is needed for use with this type of boiler.
Maintenance
Some log boilers come with automatic de-ashing, in which case
you will only need to empty the ash bins on a weekly/monthly basis,
dependent upon moisture content of the fuel and level of use.
If you don't have auto de-ashing, excess ash needs to be removed
from the boiler's loading chamber following each use. You should
usually leave some ash in the combustion chamber to provide a
burning bed for the logs.
Air openings in the combustion chamber should also be
checked.
When cold, and on a monthly basis, a more detailed clean is
usually required necessitating the removal of accessible combustion
chamber parts.
The fan should be cleaned every three months.
Log boilers must be serviced by the manufacturer or installer
annually.