Quick Start Manual

16.0 Operational Flow Chart
60
© Baxi Heating UK Limited 2005
16.2 Central Heating Mode
1. Standby: The diverter valve, pump, fan, spark
generator and gas valve are off. If the timer and room
stat are on then Diverter Valve moving to CH position
occurs.
2. Diverter Valve moving to CH position: The diverter
valve moves to the CH position while the pump, fan,
spark generator and gas valve are off. After 6 seconds if
the flow temperature is less than the set point then
Pump On occurs. After 6 seconds if the flow
temperature is greater than the set point then Pump
Overrun occurs.
3. Pump On: The diverter valve and pump are on while
the fan, spark generator and gas valve are off. After 10
seconds if the flow switch has made then Fan Pre-Purge
occurs. After 10 seconds if the flow switch has not
made then Anti-cycle occurs.
4. Fan Pre-Purge: The diverter valve, pump and fan are
on while the spark generator and gas valve are off. After
5 seconds Ignition occurs.
5. Ignition: The diverter valve, pump, fan, spark
generator and gas valve are on. If a flame is detected
then Burner On occurs. If a flame is not detected within
5 seconds and less than 5 ignition attempts have been
made then Fan Purge occurs. If a flame is not detected
within 5 seconds and 5 ignition attempts have been
made then Ignition Lockout occurs.
6. Burner On: The diverter valve, pump, fan and gas
valve are on while the spark generator are off. Flow
temperature is controlled by varying the fan speed (and
thereby the gas rate) to achieve optimum operation. If
the flow temperature is greater than the set point or
the timer is off or the room stat is off then Pump
Overrun occurs. If the TRVs all shut down then Anti-
cycle occurs.
7. Pump Overrun: The diverter valve and pump are on
while the fan, spark generator and gas valve are off.
After 1 minute Anti-cycle occurs.
8. Anti-cycle: The diverter valve, pump, fan, spark
generator and gas valve are off. After 3 minutes Diverter
Valve moving to CH position occurs.
9. Ignition Lockout: The diverter valve, pump, fan, spark
generator and gas valve are off. The boiler can only be
reset by manually using the reset button.
NOTE: If a tap or shower is switched on during CH
Burner On then DHW Burner On occurs. If a DHW
demand occurs during any other part of CH
operation then DHW Purge occurs.
Standby.
Timer & Room Stat
on ?
NO
6 second
Diverter Valve moving to
CH position
Burner On.
Ignition
Lockout.
10 second
Pump On.
Ignition done and
5 attempts made ?
Ignition done
and less than 5
attempts made ?
Flow temperature
less than set point ?
YES
NO
1 minute
Pump Overrun.
YES
YES
YES
Timer off
or temperature >
set point or room
stat off ?
NO
Primary Flow
Switch made ?
5 second
Fan Pre-Purge.
Flame Detected ?
5 second
Ignition Period.
3 minute
Anti-cycle.
All TRVs
shut down ?
Timer off or
room stat off ?
YES
NO
YES
YES
YES
YES