In addition to making sure that you property is as energy
efficient as possible before you install your boiler, see reviewing energy
efficiency, there are additional steps you can take to maximise
the efficiency of your wood fuelled boiler, which have been covered
in loosely in points 1-9 of this guide to a successful installation
but are worth repeating as maximising the efficiency of
your boiler is essential if you are to realise the full financial
and environmental benefits of a woodfuelled heating
system:
1) Ensure the size of your boiler has been correctly
specified. Getting your boiler or stove size right
will save you money. Over specifying your boiler will lead to
higher fuel costs and carbon emissions. Wood fuel boilers
typically work best under a relatively constant load. So,
to maximise efficiency, it is worth fitting a wood
fuel boiler that provides between 80%-85 % of the heat
load,
click here for more on boiler sizing. The peak
load can then be met through accumulator tanks, which store heat
in periods of low demand and/or by keeping your old fossil fuel
boiler to provide the top up.
2) It is essential to source fuel which meets the
specification of your boiler so check the requirements of
your boiler before arranging fuel supply, getting the moisture
content right is especially important. A fresh green
log of average moisture (approx 55% MC) content has only around
half the accessible energy content of an equivalent, well seasoned
log (approx 20-25% MC). Energy will be used to evaporate any water
in the wood before it will burn, reducing the net energy content
released as useful heat.
Ideally logs and wood chips will have a moisture content of less
than 25 per cent. Wood pellets need to be dryer - at around 8 per
cent moisture. Your supplier should give you information about how
to achieve this, if your potential supplier has any woodfuel accreditation
then they will need to meet set specifications for the scheme, so
you can be certain of the moisture content and particle size of the
fuel.
3) Ensure your boiler is maintained on a regular
basis, see your installer for details on any
weekly/monthly and annual checks.