1)
2)
2.1)
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6.
PART 2
OPERATION
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MANUAL OPERATION SWITCHES 7. After fan-limit control heats up to the factory set
point, the circulating air blower starts.
FIGURE # 3 8. The circulating air blower, burner motor and ignition
transformer remains on until the thermostat is
satisfied. Also, the solenoid valve remains open.
blower
operation switch
(low speed)
SEQUENCE OF OPERATION
power ON-
OFF switch
DNS-0574 Rev. B
Sequence of operation - Beckett
AFII, Side-wall venting:
For the Beckett AFII burner, the T-T terminal have
to be jumped on the primary control of the burner.
Normally open contact (W-R) on SPDT relay closed
when thermostat calls for heat.
Burner motor starts and spark is established. The
burner motor fan pre-purges the combustion
chamber and vent for 15 or 20 seconds,
establishing the combustion air pattern.
After prepurge period, solenoid valve opens
allowing oil to flow through nozzle.
The ignition transformer spark ignites oil spray.
Cad cell senses flame and burner continues to fire.
9. Thermostat is satisfied.
10. SPDT relay contacts open, solenoid valve closes,
burner fan motor post-purges the combustion
chamber and vent for a pre-set time (30 sec. to 4
min.). The ignition transformer also continues to
spark for this time period.
11. During the post-purge cycle, the fan-limit control
cools down to the factory set point of 90 degrees
Fahrenheit, and the circulating air blower turns off.
2.2) Sequence of operation - Riello 40-
BF, Side-wall Venting:
1. Normally open contact (W-R) on SPDT relay closed
when thermostat calls for heat.
.
Burner motor starts. The burner motor fan pre-
purges the combustion chamber and vents for 10
seconds, establishing the combustion air pattern.
During this time the solenoid valve holding coil
pressure will be approximately 100 psig.
After prepurge period, solenoid valve opens,
allowing oil to flow through nozzle. At the same
time, the burner motor's ignition coil produces
spark.
4. The ignition transformer spark ignites oil spray.
5. Cad cell senses flame and burner continues to fire.
Ignition transformer ceases sparking.
6. After fan-limit control heats up to the factory set
point, the circulating air blower starts.
7. The circulating air blower and burner motor remain
on until the thermostat is satisfied. Also, the
solenoid valve remains open.
8. Thermostat is satisfied.
.
Relay contacts open, solenoid valve closes, and
then the burner fan motor post-purges the
combustion chamber and vent for a pre-set time (5"
breech model only) (0 min. to 6 min.).
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