BURNER GI 1000 DSPN-D GAS PILOT
ADJUSTMENT PRINCIPLE DIAGRAM
DESCRIPTION OF OPERATIONS WITH METHANE
GAS (S
° 0002910770)
EE N
The through put rate variation range available is approximately from
1 to 1/5 in respect to the maximum throughput rate of the applian-
ce. The burner is equipped with a limit microswitch which inhibits
start-up if the flow regulator is not set to minimum. In accordance
with safety standards, burner ignition is preceded by a pre-purge
stage of the combustion chamber. During the pre-purge stage the
air and gas supply regulating servomotor provides the maximum
aperture, so that pre-purge, takes place with the maximum aperture
for air intake.
From the above, the total pre-ventilation time is provided by:
air shutter opening time + pre-purge time + time for return of air
shutter to minimum position .
If sufficient pressure is detected by the ventilation air pressurestat,
the ignition transformer will cut in at the end of the ventilation phase
and later the pilot flame valves will open. The gas will now reach
the combustion head, mix with the air delivered by the fan, and
ignite. Gas throughput is regulated by the flow regulator incorpo-
rated in one of the two pilot flame valves. The ignition transformer
disconnects after the pilot flame valves open. At the end of this
sequence of events the burner will be running on pilot only. Pilot
flame presence is monitored by the UV photocell.
At this point the programmer relay resets lockout position and supplies
power to the main valves causing them to open. The gas passes
trough the main valves and flows out of the combustion head in the
quantity permitted by the "minimum" setting of the flow regulator valve.
The main flame of the burner is now ignited at the minimum setting.
The pilot circuit cuts out after the main valves open. The modulator
servo-motor cuts in after the main valves open, and on a consent
signal from the modulating thermostat or pressurestat (assuming they
are set a temperature or pressure value in excess of the temperature
or pressure in the boiler), the servo-motor will start turning to provide
a gradual increase in the supply of gas and combustion air until the
maximum rated flow at which the burner has been set is obtained.
Gas distribution is not determined by the main valve but by
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the position of the gas distribution adjustment valve (see
drawing 0002933530).
The burner continues to operate under maximum flow conditions
until temperature or pressure reach a level that is sufficient to cause
one of the modulation detectors to cut in; at this point the modu-
lator servo-motor will turn in a reverse direction. Reverse rotation
of the servo-motor, and consequently reduction in throughput of
gas and combustion air, is effected in a series of short steps. By
this method, the modulation system operates towards bringing into
line the amount of heat supplied to the boiler and the heat that the
boiler puts out to the service. During operation of the burner, the
modulating detector mounted on the boiler detects variations in the
demand and automatically adjusts the supply of fuel and combustion
air by causing the modulating servo-motor to turn in increase or
decrease direction. If even at minimum throughput the threshold
value (temperature or pressure) setting of the shut down device is
reached, the shut down device will operate and the burner will turn
off. When the temperature or pressure drops below the shut down
device intervention threshold, the burner will cut in once again,
following the sequence of events described above. If a flame is
not detected within the safeti time, the control equipment goes into
"lockout" mode (complete shut down of the burner and illumination
of the lockout indicator light).
To release the lockout condition, press the reset button.
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