Dunkirk Helix VLT Vertical Laser Tube, Wall Hung 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.
S t a n d b y : N o D e m a n d
Heat
Demand?
DHW CH
Pump on
Supply
Temperature
<Setpoint?
15 Second
Prepurge
Ignition
Sparking
No
Yes
No
Yes
After 2 seconds
APPENDIX A - CONTROL MODULE