52
icos system -
Installation and Servicing
F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING F
AUL
T FINDING
FAULT FINDING
79 H.....4.... (DRY FIRE THERMISTOR ERROR)
Is the system filled and vented and all
isolation valves open ?
Is the pump operating correctly?
Ensure flow through system.
YES
NO
H9/L9
(HEAT EXCHANGER OVERHEAT)
Check wiring for continuity from the
PCB to the dry fire thermistor
Can the fault condition be reset by switching off
the mains supply to the boiler ?
NO
Are thermistor values correct ?
Replace PCB
Replace thermistor
Fill and vent the
system and open all
isolating valves
YES
Are thermistor values correct ?
Inspect heat
exchanger for
blockage or damage
in the flueways.
Clean or replace as
necessary
Replace thermistor
NO
YES
NO
81 H......n..... (PHASE REVERSAL ERROR)
Check wiring to the boiler for
reversed live and neutral
80 H......F..... (FLAME DETECTION ERROR)
Replace flame detection electrode
Is there continuity between the 2 terminal pins ?
NO
YES
Remove flame detection electrode terminal from PCB
Replace PCB
Check resistance, using a suitable multimeter
connected across the dry fire thermistor
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
Check resistance, using a suitable multimeter
connected across the thermistor 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
200214-11.pmd
17/11/2006, 09:36
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