Functional Diagram - ACV BG 2000-S Serie Manual De Instalación, Utilización Y Mantenimiento

EN
2
OPERATION
The BG 2000-S burner is fitted with a gas valve – venturi assembly, an electronic controller, a fan, a
flame holder and lighting and ionisation electrodes.
CONTROLLING THE AIR – GAS MIXTURE
As the fan sucks in air through the venturi, a drop in pressure (P1) is produced in the neck of the venturi. The
gas valve regulator then reacts to maintain a pressure differential equal to the offset value between the
pressure at the gas valve outlet (P2) and atmospheric pressure (P3): P2 – P3 = offset
If the air flow decreases, P1 increases; the same occurs for P2; P2 is then >P3; the regulator R is moved higher
to make P2 – offset = P3; pressure P4 falls and the valve C is turned down: the gas flow decreases.
By careful adjustment of the offset, an air – gas pressure ratio of 1 is obtained, regardless of the fan speed.
The pressure differential between the venturi neck and the gas valve outlet then causes gas to be sucked
through the venturi.
The gas flow adjustment screw can be used to adjust the quantity of gas injected for a given air flow, which will
set the %CO2 in the flue gas. A given output can then be set simply by adjusting the speed of rotation of the
fan and the % CO2 to preset values.
LIGHTING AND FLAME CONTROL
The S 4565 AD 2080 control unit performs the tasks of lighting the burner by producing a spark at the ignition
electrode, and maintaining the flame when the gas valve is opened by measuring the ionisation current.
The lighting sequence is shown in the diagram below:
When the boiler thermostat detects a demand for heat, the fan starts; after 15 seconds of preliminary flushing,
the gas valve is opened and simultaneously a spark is produced. If an ionisation current is detected in the first
5 seconds, combustion occurs normally until the end of the demand. If not, the gas valve is closed and the fan
stopped, the burner being in safety mode. It must then be reset manually before lighting is attempted again.

FUNCTIONAL DIAGRAM

1. Air 3. Venturi
2. Gaz 4. Fan
BURBER TUBE GAS
(illustrations E / F / G)
The air-gas mixture leaving the gas valve - venturi assembly is forced into the burner tube gas and combustion
spreads evenly around the burner.
BG 2000-S burners are fitted with three different types of flame holder: two are made of stainless steel
for outputs less than 60 kW, the others
(illustration E)
the flame better. It also gives longer life and considerably lower pollution emissions.
(illustration D)
15s
5s
(illustration D)
5. Offset adjustment screw
6. Gas flow a adjustement screw (CO
(illustrations F / G)
Ionisation
Spark
Gas valve opens
Fan
Thermostat
7. Air - gas mixture
)
2
receive metal fibre (NIT) which distributes