Baxi Combi 133 HE Plus Installation & Servicing Instructions Manual page 59

DHW temperature
less than set point ?
Flame Detected ?
Tap or
shower off & DHW
temperature >
set point ?
shower off & DHW
Pump Overrun.
© Baxi Heating UK Limited 2005
Standby.
Tap or shower
switched on ?
YES
5 second
Fan Pre-Purge.
and less than 5
attempts made ?
YES
5 second
Ignition Period.
Ignition done and
5 attempts made ?
YES
shower off & DHW
Burner On.
temperature =
CH Burner On.
Tap or
temperature =
set point ?
YES
1 minute
Tap or shower
Standby.
16.1
1. Standby: The diverter valve, pump, fan, spark
generator and gas valve are off. If a tap or shower is
switched on then Fan Pre-Purge occurs.
2. Fan Pre-Purge: The pump and fan are on while the
diverter valve, spark generator and gas valve are off.
After 5 seconds if the DHW temperature is less than
the set point then Ignition occurs.
YES
3. Ignition: The pump, fan, spark generator and gas valve
are on while the diverter valve is off. If a flame is
detected then Burner On occurs. If a flame is not
detected within 5 seconds and less than 5 ignition
Ignition done
attempts have been made then Fan Pre-Purge occurs. If
a flame is not detected within 5 seconds and 5 ignition
attempts have been made then Ignition Lockout occurs.
4. Burner On: The pump, fan and gas valve are on while
the diverter valve and spark generator are off. DHW
temperature is controlled by varying the fan speed (and
thereby the gas rate) to achieve optimum operation. If
the hot water tap is turned off and the DHW
temperature has been reached and there is a Central
Heating demand then CH Burner On occurs. If the hot
water tap is turned off and the DHW temperature has
been reached and there is no CH demand then Pump
YES
Overrun occurs. If the hot water tap is turned off and
the DHW temperature has been exceeded and there is
Ignition
no CH demand then Standby occurs.
Lockout.
5. Pump Overrun: The pump is on while the diverter
valve, fan, spark generator and gas valve are off. If a tap
or shower is switched on then Fan Pre-Purge occurs.
Tap or
After 1 minute Standby occurs.
set point ?
6. 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.
YES
switched on ?
16.0 Operational Flow Chart
Domestic Hot Water Mode
59