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FAULT FINDING FAULT FINDING FAULT FINDING FAULT FINDING FAULT FINDING
Ideal Logic System - Installation and Servicing
SECTION 4 - FAULT FINDING
4.7 ‘F3’ - FAN FAULT
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
Rectify Wiring & connections
Is there 230Vac at the Blue and Brown connections
to the 3 way connection on the Fan?
NO
Replace PCB
Replace Fan
NO
YES
4.8 ‘L4’ OR ‘F4’ - CONTROL / NO FLOW THERMISTOR FAULT
4.9 ‘F5 OR L5’ - RETURN THERMISTOR FAULT
Remove the Return Thermistor from the CH Return
Pipe and disconnect the wires.
Check the resistance using a suitable multimeter
connected across the thermistors terminal pins.
At 25
o
C expect 9,700 - 10,300 Ohms
At 60
o
C expect 2,400 - 2,600 Ohms
At 85
o
C expect 1,000 - 1,100 Ohms
Is the Thermistor value correct?
YES NO
Replace PCB
Fit a new Thermistor
Is there continuity between the PCB and Thermistor?
NO
YES
Check and replace wiring as
necessary
4.10 ‘F6’ - OUTSIDE SENSOR FAULT
Disconnect the wires to the outside sensor.
Check the resistance using a suitable multimeter
connected across the Outside Sensors terminal pins.
At 0
o
C expect 31,000 - 35,000 Ohms
At 15
o
C expect 15,000 - 16,500 Ohms
At 30
o
C expect 7,700 - 8,500 Ohms
Is the Outside Sensor value correct?
Replace PCB
Fit a new Outside Sensor
Is the wiring securely connected between the
incoming terminal block boiler connection of
the Outside Sensor and the PCB?
NO
YES
Securely connect the wiring at
the Terminal Block and the PCB
Is the wiring securely connected at both the boiler and
Outside Sensor?
YES
YES NO
NO
Securely connect the wiring at both the
boiler and Outside Sensor
Disconnect the wiring from the Flow Thermistor
Check the resistance using a suitable multimeter connected
across the Thermistor’s terminal pins.
At 25
o
C expect 9,700 - 10,300 Ohms
At 60
o
C expect 2,400 - 2,600 Ohms
At 85
o
C expect 1,000 - 1,100 Ohms
Is the Thermistor value correct?
Is the wiring securely connected to the
low voltage 6 way connector at the front
left hand side of the PCB?
YES
Replace PCB
Fit a new Thermistor
NO
Securely connect the
wiring to the PCB
Is the wiring securely connected to the Flow Thermistor
(located in the top of the Heat Exchanger?)
YES
YES NO
NO
Securely connect the wiring to the Water
Flow Thermistor
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