IDEAL icos system HE15

57
icos system - Installation and Servicing
FAULT FINDING FAULT FINDING FAULT FINDING FAULT FINDING
FAULT FINDING
84 H.....4.... (DRY FIRE THERMISTOR ERROR)
Is the system filled and vented and all isolation
valves open, including TRV's & Bypass?
Check the pump is operating correctly in
Heating & DHW and check temp diffs across
Flow & Return.
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 ?
Check that a permanently open
bypass circuit is available during
the pump over-run period after
boiler shutdown. This can be
provided by either an automatic
bypass valve or a heat leak radiator
(no TRV) of at least 10% of the
minimum boiler output.
Replace
thermistor
NO
YES
NO
86 H......n..... (PHASE REVERSAL ERROR)
Check wiring to the boiler for
reversed live and neutral
85 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
Note.
With V9 Primary Control PCB, overheat LA/HA or H9/L9 when
reset will display 3 horizontal lines and will not attempt to refire
until the temperature in the heat exchanger drops below 50
o
C.
Check Flow
stat is
fitted - making contact
with pipe
YES