Baxi 100 He Installation And Servicing Instructions page 41

No Fan
Is
flow temperature
NO
thermistor between 0.5kΩ
and 20kΩ ? (measured at
flow temperature
thermistor)
YES
Is
control PCB
NO
sensor connections
0.5kΩ to 20kΩ ? (I)
YES
Replace control PCB.
Replace flow
temperature
thermistor (red)
Wiring from control
PCB to sensor faulty.
br
r
Ignition
PCB
br
Sensing Electrode
w
Condensate
g/y
Trap
g/y
bk
Spark
Electrode
14.0 Fault Finding
flow temperature
> 60° C ?
fan ambient
temperature > 90° C ?
water in system and
pump on ?
Control
knob switch short
circuit when on and
open circuit when
off ? (K)
Control
PCB control knob
switch pins short circuit
when on and open
circuit when
off ? (J)
Replace control PCB.
I
Control
PCB
bk bk
b bk
b
Dry Fire
bk
b br
Flow Switch
b
r
r
Gas
Transformer
bk
br br
Valve
Thermistor
Fan Protection
Stat
g/y
bk
bk
Safety Stat
S/L N P/F
Mains Optional
Input Pump Feed
No Lockout Reset
Is
YES
temperature < 60° C.
NO
Is
YES
temperature < 90° C.
NO
Dry-fire lockout cannot
Is
be reset until there is
NO
Replace interface PCB.
YES
NO
Wiring from control PCB
to interface PCB faulty.
Connector
with
blue label
J
g br w v b g y o r bk
w
r
b
K
DC
Fan
Interface PCB
Flow overheat
thermostat will not
reset until flow
Fan protection
thermostat will not
reset until casing
water in the system
and the pump is on.
41