Unigas LMV5 Series, Manual Of Installation - Use - Maintenance, Page: 29 / 124

PART III: OPERATION
29
Fig. 6
- Burner front panel
Fuel selection:

In order to start the burner with gas or light oil, the operator must commute the selector on the burner control panel on (1) = gas, or
(2) = light oil.
If the selector is set on (1) the gas cock must be open, while the light oil cock must be closed. Viceversa if the selector is set on (2).
CAUTION: if the fuel chosen is 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.

At the end of the pre-purge time, the actuator is in the light oil ignition position: the ignition transformer is energised (lamp B4 on);
the ignitor gas valves and the light oil valves open. Few seconds after the valves opening, the transformer is de-energised and
lamp
B4 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
B2 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..
6100855
B3
G2
S1
B1
B2
G3
O5
S3
B4
G1
A2
B5
O4
Key
S1 Main switch (0=Off, 1=GAS, 2=OIL)
S3 CMF switch (0=stop, 1=low flame, 2=high flame, 3=auto-
matic) - 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
A2 AZL..