Benchmark i-mini 30 Installation And Servicing page 55

75 ALTERNATING 'F' AND '5' - 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 thermistor's terminal pins.
At 25 C expect
o
At 60 C expect
o
At 85 C expect
o
Is the Thermistor value correct?
76 ALTERNATING 'F' AND '6' - OuTSIDE SENSOR FAuLT
Is the wiring securely connected at both the boiler and
Outside Sensor?
Disconnect the wires to the outside sensor.
Check the resistance using a suitable multimeter
connected across the Outside Sensor's terminal pins.
At 0 C expect
o
C expect
At 15
o
At 30 C expect
o
Is the Outside Sensor value correct?
Is the wiring securely connected between the
incoming terminal block boiler connection of the
Outside Sensor and the PCB?
77 ALTERNATING 'F' AND '7' - LOW MAINS VOLTAGE
Contact electricity provider
i-mini -
Installation and Servicing
Fault Finding
9,700 - 10,300 Ohms
2,400 - 2,600 Ohms
1,000 - 1,100 Ohms
YES
31,000 - 35,000 Ohms
15,000 - 16,500 Ohms
7,700 - 8,500 Ohms
YES
NO
Fit a new Thermistor
YES
Is there continuity between the PCB and
the Thermistor?
NO
Check and replace
wiring as necessary
NO
Securely connect the wiring at both the
boiler and Outside Sensor
NO
Fit a new Outside Sensor
Securely connect the wiring at the
NO
Terminal Block and the PCB
Replace PCB
YES
YES
Replace PCB
55