11
3328
GB
4.
BURNER OPERATION
4.1
ADJUSTMENT BEFORE FIRST FIRING
The following to be made are:
Open the manual valves located upline from the gas train.
Bleed the air from the gas pipes using the screw on the socket (Pag. 5).
4.2
BURNER START-UP
Switch on the burner's power and close the thermostat. The burner starts in pre-purging mode at top speed.
Speed subsequently decreases to the START value and the burner fires. If however the fan starts up but no flame
has appeared at the end of the safety period, the burner goes into lockout. Reset and wait for a new start-up
attempt. If the burner still does not fire, the problem may be that gas is not reaching the combustion head within
the 3-second safety time.
Turn screw V1 on the gas valve mixer anticlockwise slightly (Page 5).
Once the burner has fired, the next step is to complete the burner's other adjustments.
4.3
FAN ADJUSTMENT
Modulation is based on variable-speed technology. Combustion air delivery can be adjusted by varying the motor’s speed
(rpm). The proportioning gas train, depending on the pressure detected in the purging circuit, delivers the right amount of
fuel. Hence the output delivered is adjusted by varying the motor’s speed of rotation. Motor speed can be adjusted by
means of the three Trimmers (see figure below).
4.4
GAS VALVE ADJUSTMENT
The regulation of the gas delivery is achieved using the two screws V1 and V2.
To vary the maximum gas delivery turn screw V1.
-
To increase the delivery: turn the screw in an anticlockwise direction (unscrew)
-
To reduce the delivery: turn the screw in a clockwise direction (screw up)
To vary the minimum gas delivery act on the screw V2 on the gas valve.
Remove the protective screws and turn the screw inside with an allen spanner.
-
To increase the delivery: turn the screw in clockwise direction (screw)
-
To reduce the delivery: turn the screw in anticlockwise direction (unscrew)
Definition of the fan adjustments:
The adjustments are made by adjusting the three potentiometers on the control box.
STAR: Determines the air in the start phase
(1980 - 4020 rpm)
MIN:
Determines the modulation minimum
(1020 - 1980 rpm)
MAX:
Determines the modulation maximum
(4020 - 6300 rpm)
The adjustment of “MIN” immediately cuts in at the end of the prepurging delineated from the opening of the valve
and the presence of the discharge. The enabling of the maximum modulation with “MAX” happens every 10 sec
from the opening of the valve.
MA
X
START
MI
N
D9771
Maximum output
Start
Minimum output
Fig. 5
