Dunkirk Excelsior EXB Series - Manual (Page 8)

8
Beckett NX
1. Room temperature drops, thermostat calls for heat.
2. Pre-purge begins, lasting 5 to 15 seconds.
3. Oil solenoid and BVS are energized
4. Oil Solenoid opens allowing oil to reach Burner
Electrodes. Burner ignition begins.
5. If vent is clear, pressure switch closes, Cad cell detects
light from combustion the primary control safety circuit
disconnects allowing combustion to continue. BVS is
energized.
6. After 15 to 45 seconds (depending on primary control
characteristics), electric spark across electrode tips
stops, combustion continues.
7. Boiler continues operation and reaches “steady state”,
point at which system temperature stabilizes.
8. Room temperature rises, thermostat is satisfi ed,
heating contacts open.
9. Oil solenoid valve closes, combustion stops, burner
motor remains on to complete Post Purge Cycle.
Post Purge time can be 0 to 8 minutes depending on
settings. Factory default is 2 minutes. Timing can be
changed using Beckett 5206 Genisys display.
10. Boiler remains idle until next call for heat.
Riello 40BF
1.
Room temperature drops, thermostat calls for heat.
2. Pre-purge begins, lasting 5 to 15 seconds. BVS is
energized.
3. If fl ue is clear, pressure switch allows ignition sequence
to continue.
4. Oil Solenoid opens allowing oil to reach burner
electrodes. Burner ignition begins.
5. Cad cell detects light from combustion, disconnects
primary control safety circuit, allowing combustion to
continue.
6. After 15 to 45 seconds (depending on primary control
characteristics), electric spark across electrode tips
stops, combustion continues.
7. Boiler continues to operate and reaches “steady state”,
the point at which the system temperature stabilizes.
8. Room temperature rises, thermostat is satisfi ed,
heating contacts open.
9. Oil solenoid valve closes, combustion stops, burner
motor remains on to complete post purge cycle. Post
purge time can be 10 seconds to 5 minutes depending
on settings. Factory default is 45 seconds. Timing can
be changed by rotating dial on Riello burner fan-off
timer control board.
10. Boiler remains idle until next call for heat.
Figure 10 - Air Shutter Setting
Figure 9 - Flex Vent Assembly Detail
SEQUENCE OF OPERATION