Ideal Heating i305 - Page 49

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FAULT FINDING FAULT FINDING FAULT FINDING FAULT FINDING FAULT FINDING
Installation and Servicing
SECTION 4 - FAULT FINDING
Display Fault Action
HOT WATER
PREHEAT
f8
OFF
Primary Thermistor
Fault
Remove harness to primary return thermistor and using a multi-meter
measure the resistance of the thermistor – This should be around 10kΩ in
ambient conditions. If thermistor is functioning correctly reconnect harness
to ow thermistor and reset unit. If thermistor is not functioning correctly
replace item. If fault persists, replace PCB (see Section 3.20).
HOT WATER
PREHEAT
F9
OFF
PCB Fault Replace PCB using the process as shown in Section 3.20.
HOT WATER
PREHEAT
L9
OFF
PCB Fault Replace PCB using the process as shown in Section 3.20.
HOT WATER
PREHEAT
fp
OFF
Pump Failure
Check system water pressure is between 1 and 1.5 bar on the system
pressure gauge. If system pressure is low increase the pressure using the
lling loop (see Section 2.5). Check system for blockages and ush system if
necessary. If fault persists, replace pump (see Section 3.10).
HOT WATER
PREHEAT
fc
OFF
DHW Thermistor
Fault
Remove harness to DHW thermistor and using a multi-meter measure
the resistance of the thermistor – This should be around 10kΩ in ambient
conditions. If thermistor is functioning correctly reconnect harness to ow
thermistor and reset unit. If thermistor is not functioning correctly replace
item. If fault persists, replace PCB (see Section 3.20).
HOT WATER
PREHEAT
F
OFF
OpenTherm Plus
Fault
Check connection between smart thermostat and HIU. Refer to Smart
thermostat manual fault nding.