Unigas N880X-FGR, Руководство по установке, использованию и обслуживанию, Страница: 33 / 60

PART III: OPERATION
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Integrated proving system burners equipped with BT3x
When the burner is switched off, the BT3x device proceeds with an evacuation test, opens the EV1 valve (burner side) and makes sure
to bring the test volume (space between EV2 and EV1) to atmospheric pressure.
The BT3xx device uses only one pressure switch (PGMIN/LT) mounted between the EV1-EV2 valves which acts as a leak test in the
"Gas valve seal" test phase and a minimum pressure pressure switch during "Start and burner operation" .
The BT3xx equipment performs a tight check of the gas valves according to the pressure felt by the pressure switch installed between
the valves (PGMIN / LT).
Case A: the pressure between the valves EV1 and EV2 is equal to zero.
- The BT3xx device opens the EV1 valve for a few seconds and fills the chamber between EV1 and EV2.
- The PGMIN / LT pressure switch senses the pressure (which remains present and stable) and closes the contact giving consent to
continue the cycle to the equipment.
Case B: presence of pressure between the valves EV1 and EV2.
- In this case the BT3xx device opens the EV2 volvo to evacuate the gas between EV1 and EV2.
- In this way the PGMIN / LT pressure switch permanently feels zero pressure and opens the contact.
- The cycle continues by opening the valve EV1 to pressurize the section between the valves EV1 and EV2.
- The PGMIN / LT pressure switch senses the increase in pressure (which remains present and stable), closes the contact giving
consent to the equipment to continue the starting cycle.
When the burner is switched off due to the intervention of the thermostat / boiler pressure switch, the BT3xx keeps the EV2 gas valve
open to allow the pressure between the gas valves to be released and the PGMIN / LT pressure switch contact to rest and ready to
restart the burner.
AIR FLOW AND FUEL ADJUSTMENT
Adjustments - brief description
The air and fuel rates adjustments must be performed at the maximum ouptput first (“high flame”): see the Lamtec.. related manual..

Check that the combustion parameters are in the suggested limits.

Check the flow rate measuring it on the counter or, if it was not possible, verifying the combustion head pressure by means of a dif-
ferential pressure gauge, as described on par. “Measuring the gas pressure in the combustion head”.

Then, adjust the combustion values by setting the “gas/air” ratio” curvepoints (see the Lamtec.. related manual).

Set, now, the low flame output, in order to avoid the low flame output increasing too much or that the flues temperature gets too low
to cause condensation in the chimney.
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
Fuel
Recommended (%) CO
2
Recommended (%) O
2
Natural gas 9 ÷ 10 3 ÷ 4.8
Light oil 11.5 ÷ 13 2.9 ÷ 4.9
PS
PGMIN/LT
EV2 EV1