12
2009-03
RVR
Energy Technology Experts
Operation – from start to stop
Operation – from start to stop
Viking Bio's operation procedure is very similar to an oil burn-
er. The big difference is that the start and stop phases take
much longer. Under normal conditions, it takes four to fi ve
minutes before the fl ame is relit.
The burner's operational mode, from start to stop, is split into
four phases:
1. Start
2. Set fl ame
3. Operation
4. Cooling
Prerequisites for start:
• Overheating guard, thermostat and possibly closed safety
gates.
• Possible alarm reset.
• The burner receives pellets.
Start
•
The thermostat demands heat.
If start delay has been chosen, the "RUNNING" indicator will
fl ash during the time that the set delay is active.
Where the burner controls the boiler thermostat, all its in-
dicators will start to fl ash if it is set at a lower temperature
than the temperature setting on the burner itself. The boiler's
thermostat must be set at the highest value, the temperature
setting on the burner must be set to at at least 10-15°C lower
than this.
•
The fan starts and runs at top speed for twenty seconds in
order to ventilate the boiler and fl ue-gas channels. At the
same time, back pressure in the burner chamber is meas-
ured. If the result from fi ve measurements shows too much
pressure, the burner stops and gives an "Overpressure –
burner chamber" alarm.
•
The fan stops. A start dosage of pellets is given and the igni-
tion element begins to heat up. For a start dosage, the screw
runs about 3.5 revs.
•
The fan intermittently goes into a fl ashing "LOW" indication.
When a fl ame is found, it switches to a fi xed band of light.
The burner makes three attempts to start. The fi rst try is de-
scribed above. Where a fl ame is not lit on the fi rst attempt,
the fan will stop for a short time and then start again at a
low speed at the same time as the ignition element is re-
engaged. The third attempt is identical to the others.
If there is no fl ame after the third attempt to start, the fan
stops for a short period and then picks up speed in three
stages to a high speed.
The burner normally ignites at the fi rst attempt and a fl ame
will be found after four to fi ve minutes. Where the burner fails
to establish a fl ame, as described above, it will stop operat-
ing and a "Failed start" alarm will appear. The likeliest cause
for this is that the draught is too powerful, the grate is incor-
rectly placed, or the burner is not being fed with pellets.
Set fl ame
• Burner is running with fl ame.
•
Fan sped increases in stages, so as to establish a stable bed
of embers on the grate.
•
Pellets are fed in. The screw runs approx. a quarter turn for
each feed. Pause time depends on output setting.
If the fl ame disappears during this phase, the controls switch
to the start phase, but no pellets are fed in.
Operation
•
Fan speed is determined by output setting. The "OUTPUT"
indicator gives a fi xed or fl ashing light depending on the
operational mode. The "LOW" indicator lights up with a fi xed
band.
•
Pellets are fed in.
If the fl ame disappears during operation, a smaller amount
of pellets is issued and the ignition element attempts to cre-
ate a fl ame. "LOW" fl ashes and it switches to a fi xed band of
light when a fl ame is found.
The burner then goes into "establish fl ame" mode in order
to gradually establish a stable bed of embers and then goes
into operational phase.
If the attempt to establish a fl ame fails, the burner will stop
and give a "Failed start" alarm.
The reason why a fl ame disappears is that the draught is too
powerful, the grate is incorrectly placed, or the burner is not
being fed with pellets properly.
Cooling
•
Operational stop by thermostat.
If the burner controls the boiler temperature and is governed
by an boiler thermostat which breaks down whilst in opera-
tion, pellet feeding is terminated, the burner switches to the
cooling phase and then closes down with all its indicators
fl ashing. Restart requires a reset of the alarm – see Resetting
the alarm page 16. The boiler thermostat must be set at the
highest value, the temperature setting on the burner is set to
at least 10-15°C lower than this.
•
Pellet feeding ceases.
•
The "OUTPUT" indicator fl ashes – one long + two short.
•
The fan runs at top speed and continues for 90 seconds af-
ter the the fl ame goes out. This is to ensure that all pellets on
the grate are burned. The "LOW" indicator goes out.
•
If, for four cycles, the fan runs at top speed all pellets in the
grate will be burned up.
•
The burner stops. Only the "RUNNING" indicator is lit.
Long running time
When heating requirements are substantial, or when burner
output is too small for the actual heating requirements, the
burner's running time is very long. In order to retain a good
combustion level and stable operation, the burner automati-
cally switches after approx. three hours in operation and goes
to its cooling/clean blowing phase, in order to blow clear any
ash residue which has built up in the grate. A reset to opera-
tional mode occurs automatically.
OPERATION Normal operation
–
Start delay
•••
OUTPUT High
–
low
–•
Cooling phase
–••
FLAME Start
phase
•••
Flame
–
ALARM
High temperature in downpipe
–
Failed
start
–••
High ambient temperature
–•••
Fan not working
–••••
Overpressure boiler chamber
–•••••
Start element not working
••••••••
