Adjustments For Gas Operation; Light Oil Operation - Unigas HTLX 1025.1 Installation Manual

ADJUSTMENTS FOR GAS OPERATION

Air flow and gas adjustment
startup the burner by selecting GAS by means of the switch on the burner control panel

Adjust the air and gas flow rates, in according to the "air/gas ratio" curvepoints setting procedure on the LMV manual,. Check con-
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tinuosly, the flue gas analisys, to avoid combustion with air excess.
Once the butterfly valve is completely opened, acting on the pressure stabiliser of the valves group, adjust the gas flow rate in the

high flame stage as to meet the values requested by the boiler/utilisation:
If necessary, change the combusiton head positionl.
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The air and gas flow rate are now adjusted at the maximum power stage: go on with the point to point adjustement, as to reach the

minimum output
Adjust the pressure switches
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Choose the typer of fuel by turning the S1 switch, on the burner control panel.
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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.
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Check the series of thermostats and pressure switches turn the burner to on.
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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..
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
WARNING! During commissioning operations, do not let the burner operate with insufficient air flow (danger of
formation of carbon monoxide); if this should happen, make the fuel decrease slowly until the normal combustion
values are achieved.
WARNING! the combustion air excess must be adjusted according to the values in the following chart.
Recommended combustion parameters
Recommended (%) CO
Fuel
Natural gas
Light oil
Recommended (%) O
2
9 ÷ 10
11,5 ÷ 13
29
PART II: OPERATION
2
3 ÷ 4,8
2,9 ÷ 4,9