Dunkirk Helix VLT Vertical Laser Tube, Wall Hung Modulating Condensing Boiler - Manual (Page 72)

72
1.4 Sequence of Operation
Operational State User Interface Display 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.
Flame
Detected?
Gas Valve
Energized
Flame
Detected?
Heat Demand
Met?
DHW
Priority
Mode
Simultaneous
DHW + CH
Demand?
No
Yes
No
Yes
See Max DHW
Priority Time
Setting
No
After 2 seconds
After 3 seconds
No
30 second
post purge
Yes
Yes
Lockout
Error A21
Note:
5 Ignition
trials,
then
Lockout A01
APPENDIX A - CONTROL MODULE