Unigas P20, Installation, Operation And Maintanance Manual, Page: 24 / 52

PART II: OPERATION 24
OPERATION
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Bring to the ON position the mains switch A on the burner electrical board front panel.
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Check the flame control device is not in the lockout position (light B on), if necessary reset it by means of the pushbutton C
(reset);
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Verify that the control thermostats or pressure switches give the consent to the burner to operate.
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Check the gas supply pressure is sufficient (light D on).
Only burners equipped with leakage control device: the check cycle of the leakage control device starts; the completion of
this check is signalled by the light of the lamp on the device. When the valves check is finished, the start up cycle of the burner
begins. In the case of a leak in a valve, the leakage control device locks and the lamp E lights.
To reset the device operate on the device pushbutton.
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When the startup cycle begins, the servocontrol drives the air damper to the maximum opening position, the fan motor starts
and the pre-purgue phase begins.
During the pre-purgue phase, the complete opening of the air damper is signalled by the lamp F on the frontal panel of the
electrical board.
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At the end of the pre-purgue phase, the air damper goes to the ignition position, the ignition transformer comes on (signalled
by the lamp H) and 3 seconds later the solenoid valves EV1 and EV2 are energized (lights L and I on the front panel).
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3 seconds after the opening of the valves, the ignition transformer comes off and the lamp H turns off; subsequently:
Single stage burners: the burner is on at the maximum power; the lights F and G are on;
High-low flame burners: the burner is on in low flame (light G is on); 8 seconds later the high flame operation begins and the
burner switches automatically to high flame (light F is on) or remains in low flame operation, depending on the plant needs.
Fully modulating burners: after the posted time the modulating operation begins and the burner is driven by the modulator (P),
depending on the needs of the plant; the light F is on until the modulator drives the burner to a rise of power.
Fig. 41 - Electrical board front panel
Key
A main switch on-off
B lockout indicator light
C reset pushbutton for flame control device
D gas pressure switch consent indicator light
E leakage control device lockout indicator light (only on burners with leakage control device)
F high flame operation indicator light (or air damper open during pre-purgue phase)
G low flame operation indicator light
H ignition transformer operation indicator light
I valve in operation indicator light for EV2
L valve in operation indicator light for EV1
M indicator light for fan motor overload tripped (only three-phase burners); to reset the overload tripped, open the electrical
board.
P modulator (fitted only on fully modulating burners)
F G H
M
B
I L D
E
C
A
P