Unigas HR92A, Manual Of Installation - Use - Maintenance

Page: 32 / 140

PART III: OPERATION
32
- BURNER FRONT PANEL
Key
S1 Main switch (0=Off, 1=GAS, 2=OIL)
S3 CMF switch (0=stop, 1=low flame, 2=high flame, 3=automatic) - fully modulating burners only
G1 Gas valves EV2 operation signalling lamp
G2 Gas valves EV1 operation signalling lamp
G3 Gas pressure switch signalling lamp
O4 Oil pump in operation lamp
O5 Oil valve EVG operation signalling lamp
B1 Lock-out lamp
B2 High flame operation signalling lamp
B3 Low flame operation signalling lamp
B4 Ignition transformer operation lamp
B5 Thermal cutout intervention signalling light CTV
A1 Burner Modulator (only on fully modulating burners)
A2 AZL..

Choose the typer of fuel by turning the S1 switch, on the burner control panel.
CAUTION: if the fuel chosen is light oil, be sure the cutoff valves on the feed and return pipes are open.

Check the control box is not locked; if so, reset it by means of the button on LMV panel.

Check the series of thermostats and pressure switches turn the burner to on.
Gas operation

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.

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).
Light oil operation

The fan motor starts and the pre-purge phase as well. Since the pre-purge phase must be carried out at the maximum air rate, the
control box drives the actuator opening and when the maximum opening position is reached, the pre-purge time counting starts.
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A F
B3
G2
S1
B1
B2
G3
O5
S3
B4
G1
A2
B5
O4
A2
A1