© EUROHEAT DISTRIBUTORS (H.B.S) LTD. June. 2010
Instructions Part Number IN1180 Ed D1
6
Multifuel And Wood Inserts
Gas and oil are consistent fuels and inserts can be designed to obtain the maximum heat from them with the
user having to do no more than choose a heat setting. Solid fuels are almost infinitely variable and however well
an insert has been designed, its performance will ultimately depend on the way the user operates it. Whilst we
have endeavoured to make the insert as simple to operate as possible, understanding just a little about the fuels
and the way your insert was designed to burn them will be rewarded by your being able to achieve the best from
your insert with the least effort.
As a fuel, wood is visually exciting, environmentally friendly, and a renewable source of energy but it is one of
the most complex fuels to burn. Wood contains two sorts of components which burn. The fixed carbons which
burn as the glowing embers, and the compounds that vaporize when heated to burn as volatile gasses, giving
the endlessly changing flame patterns. The fixed carbon, which is charcoal, is a virtually trouble free fuel and
needs little assistance to burn cleanly, but it would be difficult to describe it as visually entertaining.
When set to its wood burning position, your insert heats the incoming air to ensure it has the minimum cooling
effect on any volatiles. The air is supplied as slowly as possible so as not to blow out any established flames
and it comes in across the full width of the insert ensuring that all parts of the insert receive an equal air supply.
Because the air enters slowly over a curved blade the air is directed towards the burning volatiles rather than the
bed of the fire, this allows the tar laden volatile components to use the incoming air as a priority. By placing a
log or two towards the front of the fire whenever the flames from previous logs die down, a bed of charcoal will
build up. This will be virtually pure carbon and capable of burning for incredibly long periods without causing any
tar deposits on the insert’s glass even when the air supply is reduced to minimal setting.
Always put logs on to the fire before flames from previous logs have extinguished, this will ensure that when the
new logs begin releasing gasses it will ignite. Unburned gasses will cause smoke and tar deposits and wastes
potential heat. Putting on too much wood at one time will both restrict the air supply and cool the combustion
chamber making it more difficult for the gasses to burn cleanly.
Never put on fresh wood whilst operating the insert with a minuscule air supply as a technique for operating
for long periods without attention, it will cause both chilling and air restriction. Properly controlling the rate at
which wood burns is not simply a matter of restricting the air supply, nor running the insert with a very small
fire, it is maintaining the temperature and ignition flames in the insert whilst balancing the release of gasses to
match the chosen air supply.
No two woods have the same burning characteristics but all wood contains water. It is difficult to quantify the
amount of water any log might hold whilst its exterior feels dry but it would not be unreasonable to estimate a
mug full from a good sized, poorly seasoned, Imagine pouring that onto your fire every time you introduce a new
log and you will realize its obvious effect of cooling the fire. What is not so obvious is that the moisture mixing
with the vaporized gasses is cooling them, possibly below their ignition temperature. So the water within a wet
log cooled the insert, it has prevented much of the potential heat from the log being realized and the unburned
combustible products will be deposited as tars within the insert and flue. Advice on how to dry wood can be
found on the DVD “User Guide” supplied with the insert.
Coal suitable for inserts has only a very small proportion of components that vaporize and a far higher fixed
carbon content and when the insert is set to its coal burning position air is supplied through the grate to the
underside of the fire bed to supply the carbon directly. There will be sufficient spare air travelling through the
fire bed to reach the limited gasses being released and this air will have been heated as it passed the burning
coals.
Because coals suitable for inserts have so little vaporizing content they are virtually trouble free fuels to use, but
if you are using one of the manufactured smokeless coals take care to ensure the ash pan is checked regularly
because some of them have a very high ash content; this is especially important if you change “brands” because
the ash contents can vary dramatically. Always riddle the grate before putting on loadings of coal to give the
initial release of gasses sufficient air with which to burn; failure to do so may allow the insert and flue to fill with
gasses ready to ignite.
