Sequence Of Operation - UTICA BOILERS UBSSC-050 Installation, Operation & Maintanance Manual

2.4 Sequence of Operation

Operational State
No
Heat
Demand?
Yes
DHW CH
Pump on
No
Supply
Temperature
<Setpoint?
Yes
15 Second
Prepurge
Ignition
Sparking
After 2 seconds
APPENDIX A - CONTROL MODULE
Front
Panel
User Interface Display
In-
dica-
tors
59
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 sup-
ply temperature to set point.
Boiler proceeds to ignition if supply
temperature is less than set point.
Combustion Air Blower speed
modulates to prepurge setting for
15 seconds.
Sparking initiated sequence.