Gas Operation - Unigas G258A Manual Of Installation - Use - Maintenance

PART III: OPERATION
S1
Keys
B1 Lock-out LED
B2 Hi-flame operation LED
B3 Lo-flame operation LED
B4 "Ignition transformer operation" LED
B5 "Fan motor overload tripped" LED
G1 "EV2 opening" LED
G2 "EV1 opening" LED
G3 "Gas pressure switch signal " LED
S1 Main switch
S3 Operation selector MAN - AUTO (operation in manual or automatic mode):
MIN = operation with minimum output
MAX = operation at the maximum output
A1 Burner Modulator (only on fully modulating burners)
A2 AZL..

Gas operation

Check that the control box is not in the lockout position; in case unlock it by pressing the relevant key (for further information on the

LMV.., see the related manual).
Check that the pressure switches/thermostats series enables the burner operation.

Check that the gas pressure is sufficient (signalled by an error code on the AZL.. display).

Burners fitted with gas proving system: the gas proving system test begins; when the test is performed the proving system LED

turns on. At the end of the test, the burner staring cycle begins: in case of leakage in a valve, the gas proving system stops the bur-
ner and the lamp B1 turns on.
At the beginning of the start-up cycle, the actuator drives the air damper to the maximum opening position, then the fan motor

starts up: the pre-purge phase begins. During the pre-purge phase, the air damper complete opening is signalled by the light B2 on
(see front panel).
At the end of the pre-purge, the air damper is driven to the ignition position, the ignition transformer is energised (signalled by the

light B4 on the front panel) then, few seconds later, the EV1 and EV2 gas valves are energised (light G1 and G2 on the front
panel).
Few seconds after the gas valves opening, the ignition transformer is de-energised and light B4 turns to off.

The burner operates in the low flame stage; few seconds later the two-stages operation begins and the burner output increases or

decreases, driven by the external thermostats (progressive burners) or by the modulator (fully-modulating burners).
.
Fig. 4 - Burner front panel
B4
B2 B3
S3
B5
G3
G2
G1
B1
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