Dunkirk DKVLT-050 Installation, Operation & Maintenance Manual page 72

1.4 Sequence of Operation
Operational State
After 2 seconds
Flame
Yes
Detected?
No
Gas Valve
Energized
After 3 seconds
Flame
No
Detected?
Yes
Heat Demand
Met?
No
No
Simultaneous
DHW + CH
Demand?
See Max DHW
Priority Time
Yes
DHW
Priority
Mode
APPENDIX A - CONTROL MODULE
Lockout
Error A21
Note:
5 Ignition
trials,
then
Lockout A01
30 second
post purge
Yes
Setting
User Interface Display
72
Explanation
If flame detected before Gas Valve opens
during ignition boiler will lockout.
Please refer to troubleshooting guide.
Gas Valve energized to deliver air/fuel to
burner.
If flame undetected after 3 seconds boiler
will de-energize Gas Valve and enter post
purge mode for 30 seconds.
Ignition attempted 5 times before
lockout.
Boiler will run provided all operational
and safety devices are within limits
Refer to for more information.
Control module adjusts firing rate
according to heating demand. When
Boiler detects demand met, will enter
post purge mode then standby mode.
If simultaneous demand for Central Heat
and DHW, boiler will enter DHW Priority
Mode.
Priority mode limits amount of time
boiler can run in DHW mode to meet CH
demand.
Max DHW Priority Time setting
determines maximum time allowed for
DHW heating mode.
Please refer to section Appendix A section
1.5 for more information.