Dunkirk Helix VX Vertical Laser Tube Wall Hung Stainless Steel Modulating Condensing Boiler - Manual (Page 71)

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1.4 Sequence of Operation
Operational State User Interface Display Explanation
Boiler operates in standby mode
until demand for Central Heat (CH)
or Domestic Hot Water (DHW) is
detected.
CH or DHW pump is turned on based
on type of heating demand.
(CH call is illustrated)
Control Module compares supply
Temperature to set point. Boiler
proceeds to ignition if supply
temperature is less than set point.
Combustion Air Blower speed
modulates to pre-purge setting for 15
seconds.
Sparking initiated sequence.
Heat
Demand?
DHW CH
Pump on
Supply
Temperature
15 Second
Prepurge
Ignition
Sparking
No
Yes
No
Yes
After 2 seconds
APPENDIX A - CONTROL MODULE