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8.5
CENTRAL HEATING FAULT FINDING
Upon a demand for Central Heating, (closure of the time clock
and room thermostat, where fitted), the controls should carry out
a set of start up checks, followed by an ignition sequence. Refer
to Section 5.2.
If the control has powered up correctly but does not respond to a
CH demand. Check voltage between pin 2 connector X1A
(orange wire) and pin 2 connector X1B (blue wire). If 0 V ac,
check room thermostat and clock. If 230 V ac, check control for
lockout or blocking codes, (refer to section 8.3), check operation
of the pump.
If room thermostat and clock are OK and no lockout or blocking
code exists and the control is not in anti cycle mode, then
everything should be working correctly, if not contact Halstead
Boilers Ltd Service Help Line: 01926 834834
Note: Whenever a CH demand is removed,
either by the timer, the room thermostat or by the
appliance’s internal temperature control, an anti
cycle mode is initiated which prevents the
appliance from firing in CH mode for 5 minutes.
Ensure that the control is not in this mode by
removing power from the control and restoring it
after a delay of 10 seconds.
RESET LOCK-OUT CODES
LED CODE FAULT/EFFECT REASON ACTION
● Check no air is in heat exchanger/CH system
1 Overheated appliance Water temperature greater than 105 °C
● Check plate heat exchanger is not blocked
● Check diverter valve operation
● Check flow/return thermister
Differential check
● Check flow/return thermister
faulty/Flame for
Zero check faulty DHW or CH
● Check water pressure
2
● Check pump/CH system blockage
15 seconds
● Check no air is in heat exchanger/CH system
● Check detection electrode/lead
● Check gas supply
No gas or Lockout flame Low gas pressure.
● Check gas service cock
signal/ No flame, Lockout No flame signal on ignition,
● Check gas valve and lead
3
after 5 ignition attempts or loss of signal during operation ● Check PCB/X2A & X2B connectors
● Check spark generator/spark electrode
● Check mains earth lead continuity
4 Flue gas sensor/No flame Flue gas temperature greater than 95 °C ● Check no air is in heat exchanger/CH system
water pressure
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