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A. CONTROL OVERVIEW
The Series PBC™ boiler control is one of the primary
safety devices for the boiler. It controls:
• Ignition sequence
• Temperature Limits
• Circulators
• Gas Flow
• Setpoints
• Domestic Hot Water Valve
• Fan Speed
• LWCO (When optional LWCO probe is used)
B. AVAILABLE CENTRAL HEAT MODES
BOILER CONTROL: INTERNAL WIRING & OPERATION
Table 8.1: Series PBC™ Central Heat Modes
8. BOILER CONTROL: INTERNAL
WIRING & OPERATION
Central
Heating
Mode
Mode Description
Mode Operation Restrictions
0
Fixed Setpoint
–
Demand initiated by T/TT closure
–
User chosen fixed setpoint
–
Boiler targets CH setpoint and operates of Supply temperature
hysteresis when demand is present
Not for space heating
1
Outdoor reset with Thermostat
–
Demand initiated by T/TT closure
–
Setpoint is calculated based off of Outdoor temperature and CH
demand period to improve fuel usage and boiler efficiency.
–
Setpoint Boost function for long CH demand periods.
–
Boiler targets calculated CH setpoint and operates off of Supply
temperature hysteresis when demand is present
–
When the Boost Function was active and CH demand is not present,
the CH setpoint decreases back to the calculated setpoint.
No restrictions
2
Outdoor reset with Permanent
Demand
–
Demand initiated by control logic. Always present.
–
Setpoint is calculated based off of Outdoor temperature to improve
fuel usage and boiler efficiency.
–
Boiler targets calculated CH setpoint and operates off of Supply
temperature hysteresis.
–
When CH demand is not present, calculated setpoint decreases
gradually.
No restrictions
3
Fixed Setpoint with Permanent
Demand
–
Demand initiated by control logic. Always present.
–
User chosen fixed setpoint
–
Boiler maintains CH setpoint and operates of Supply temperature
hysteresis
Not for space heating
*While accessible via the Installer menu, CH Modes 4 and 5 are not functional with the Series PBC™ boiler.
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