
Fit a new sensor
no
Disconnect the wires to the Sensor. Check the
resistance using a suitable multimeter connected across
the thermistor’s terminal pins.
At 0°C expect 32,000 - 33,000 Ω
At 10°C expect 19,000 - 21,000 Ω
At 20°C expect 12,000 - 13,000 Ω
Is the thermistor value correct?
yes
Ensure the wiring has continuity and is
securely connected
no
yes
Does the Sensor wiring between the boiler terminal strip
and the PCB have continuity and is securely connected?
Replace main PCB
Securely connect the wiring at both
the boiler and sensor
no
Is the wiring securely connected at both the boiler and
Sensor?
yes
5.10
OUTSIDE / HEADER / ROOM SENSOR FAULT (IF FITTED)
5.8 FAN FAULT
Rectify wiring & connections
no
Does the wiring from the Fan to the PCB have secure
connections at both ends and has not deteriorated?
Does the wiring have continuity?
yes
Replace main PCB
Replace Fan
no
yes
Is there 230Vac at the blue and brown
connections to the 3 way connection on the Fan?
5.9 FLOW / RETURN THERMISTOR, HEAT EXCHANGER OR FLUE THERMISTOR FAULT
Fit a new thermistor
no
Disconnect the electrical connection to the Flow
Thermistor and check the resistance using a suitable
multimeter connected across the thermistor’s terminal
pins.
At 25°C expect 9,700 - 10,300
Ω
At 60°C expect 2,400 - 2,600
Ω
At 85°C expect 1,000 - 1,100
Ω
Is the thermistor value correct?
yes
Check and replace wiring as necessary
Replace main PCB
no
yes
Is there continuity between the PCB and the Thermistor?
70
Installation & Servicing
SECTION 5 - FAULT FINDING
F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING
Содержание HEAT 2 45
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