3350
9
GB
3.6 FAN ADJUSTMENT,
(see fig. 5)
Modulation is based on variable-speed technology. Combustive air delivery can be adjusted by varying the
motor's speed (rpm). The proportioning gas train, depending on the pressure detected in the purging cir-
cuit, delivers the right amount of fuel. Hence the output delivered is adjusted by varying the motor's speed
of rotation. The motor speed can be adjusted by regulating three “Trimmers”.
4.
BURNER OPERATION
4.1
ADJUSTMENT BEFORE FIRST FIRING
The following adjustments are to be made:
- Open the manual valves located upline from the gas train.
- Bleed the air from the gas pipes using the screw on the socket START.
- Connect the diagnostic software kit to the control box: via this kit, you can view the motor's rpm.
- Check the settings chosen with the trimmers located on the control box (fig. 5).
4.2
BURNER START-UP
Close the thermostat and switch on the burner's power.
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 but no flame has appeared by the end of the safety period, the control box allows the
start-up programme to be repeated: up to 3 attempts are made.
If there is no firing by the fourth attempt, 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.
Once the burner has fired, proceed with global calibration operations.
D7238
D7237
3-pin terminals
MAX:
maximum output
START:
start-up output
power
Terminals for connecting
output regulator
Fig. 5
power adjustment
MIN:
minimum output
power adjustment
Trimmers
