51
Fault Finding
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Ideal Logic System -
Installation and Servicing
70 aLTERNaTINg ‘F’ aND ‘4’ - CONTROL / NO FLOW ThERMIsTOR FaULT
71 aLTERNaTINg ‘F’ aND ‘5’ - RETURN ThERMIsTOR FaULT
Remove the Control/No Flow Thermistor from the
Heat Exchanger 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?
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
YES
NO
NO
Replace PCB
Replace PCB
Fit a new Thermistor
Fit a new Thermistor
Is there continuity between the PCB and Thermistor?
Is there continuity between the PCB and Thermistor?
NO
NO
YES
YES
Check and replace wiring as
necessary
Check and replace wiring as
necessary
72 aLTERNaTINg ‘F’ aND ‘6’ - 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
73 aLTERNaTINg ‘c’ aND ‘2’ - BCC FaULT (BOILER ChIp CaRD)
Is the correct BCC for the boiler securely inserted into the
slot at the front left of the PCB?
(identified by the label on the BCC)
YES
NO
Securely insert the correct BCC for the boiler
into the PCB and after switching power on and
‘c0’ being shown, reset boiler.
Note.
Ensure the correct orientation of BCC by
placing “TOP” side up.
Replace the BCC with a new BCC (that is correct for the
boiler). After switching power on and ‘c0’ being shown,
press reset. Is ‘c2’ still shown?
Replace PCB
YES
REsET pROCEDURE
- To reset boiler, turn mode knob to reset position and immediately turn knob back to required setting.
