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18. Operational Flow Diagram
Mains
230V
supply
BOILER
HEAT
DEMAND
Pump
continues
for
4
minutes
DEMAND
OFF
Boiler demand
from system
junction box
AND
User control
knob ON
Run fan
20
seconds
or wait for
the end of
the fan
overrun
Boiler
demand
light on
Pump
supply
on
Ignition
sequence
Boiler cycles
to satisfy
temperature
set by facia
control
knob
Temperature
Sensor disconnected
Ignition sequence inhibited
(fan and pump may run for
short period)
Boiler
overheat
Overheat
thermostat
trip.
Lockout
light
(constant)
Protection Systems
re-attempt
ignition
(MAX 4
times)
lockout
light
(flashing)
Fan
continues
for
1
minute
FAIL
PASS
PASS
FAIL
Run pump
continuously