Unigas K890A Manual Of Installation - Use - Maintenance Download

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PART III: OPERATION

K750A

- Burner front panel



Choose the typer of fuel by turning the

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

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

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.



At the end of the pre-purge time, the actuator is in the light oil ignition position: the ignition transformer is energised (lamp

on);

the ignitor gas valves and the light oil valves open. Few seconds after the valves opening, the transformer is de-energised and
lamp

turns off.



The burner is now operating, meanwhile the actuator goes to the high flame position; after some seconds, the two-stage operation
begins; the burner is driven automatically to high flame or low flame, according to the plant requirements.Operation in high or low
flame is signalled by LED

on the burner control panel.

The fuel is pushed into the pump to the nozzle at the delivery pressure set by the pressure governor. The solenoid valve stops the fuel

immission into the combustion chamber. The fuel flow rate that is not burnt goes back to the tank through the return circuit. The nozzle

is feeded at constant pressure, while the return line pressure is adjusted by means of the pressure governor controlled by an actuator..

The fuel is pushed into the pump to the nozzle at the delivery pressure set by the pressure governor. The solenoid valve stops the fuel

immission into the combustion chamber. The fuel flow rate that is not burnt goes back to the tank through the return circuit. The nozzle

is feeded at constant pressure, while the return line pressure is adjusted by means of the pressure governor controlled by an actuator..

AIR FLOW AND FUEL ADJUSTMENT

Keys

B1 Lock-out LED
B2 Hi-flame operation LED
B3 Lo-flame operation LED
B4 “Ignition transformer operation” LED
B7 Burner ignition LED
G1 “EV2 opening” LED
G2 “EV1 opening” LED
G3 “Gas pressure switch signal ” LED
S4 Fuel selection
S7 CMF switch (0=stop, 1=high

flame,2=low flame, 3=automatic) -

fully modulating burners only

O3 “Pump motor overload tripped” LED
O4 Oil pump in operation LED
O5 Oil valve EVG operation signalling

lamp

A2 AZL..