Fault Code	Model Affected	Fault	Possible Cause
1	All	Ignition failure	Gas supply Check pressure tubes Ignition electrode gap Flame sensor electrode gap Ignition generator or lead Flame sensor electrode lead Gas valve setting Gas valve PCB
2	All	Overheat boiler lock out	Pump or flow problem Blocked heat exchanger Air in heat exchanger Overheat thermostat Thermal fuse (if open circuit then replace primary heat exchanger)
3	All	High flue thermostat temperature	Blocked or restricted primary flow Heat exchanger air flow blocked Flue restriction Flue sensor fault
4	All	Gas valve electrical connection fault	Gas valve lead connection fault Faulty gas valve Faulty PCB
5	All	Heating flow sensor fault	Flow sensor wire connections Flow sensor faulty
6	All	DHW sensor fault	DHW sensor wiring connection DHW sensor faulty
8	All	Maximum number of resets	Refer to fault history codes
10	All	Primary system pressure low	Check expansion vessel pressure (1 bar) Leak in system Expansion relief valve operated Primary pressure switch
12	All	“Cylinder sensor fault (FlowSmart only)”	Cylinder sensor wiring connections Cylinder sensor faulty
15	All	Internal wiring error	Check internal wiring connections to PCB Combination boiler DHW sensor X4 System boiler link X14 Refer to wiring diagram
16	All	Fan fault	Check fan wiring connections Fan fault PCB fault
20	All	Flame sensing fault	Check flame sensing electrode and lead PCB fault
24	All	Control panel button fault	Check for jammed control panel buttons Check for jammed PCB buttons
25	All	Overheat lock out	Air in heat exchanger Blocked or restricted primary flow Heat exchanger air flow blocked Flue restriction Flue sensor fault Pump fault Boiler or Heating circuit valve closed
27	All	Insufficient primary flow	Blocked or restricted primary flow Air in heat exchanger Boiler or heating circuit valve closed Pump fault Primary flow sensor fault
29	All	Flue sensor fault	Check sensor wiring connection Flue sensor faulty
31	All	Loss of communication with external Control (Alpha Climatic)	Remote control or receiver connection wiring Remote control or receiver
37	All	Low supply voltage	Check mains power supply Check for bad cable connections etc
38	All	Flame detected but signal lost. Ignition retries after fan purge	Check flame sensing electrode and lead Check for flue gas recirculation Check the gas valve Check flue system and termination Check gas supply/working pressure Check/adjust combustion settings
43	All	Loss of flame rectification	Check gas supply/working pressure Check flame sensing electrode and lead Check for flue gas recirculation Check/adjust the gas valve settings Check/adjust the fan speed settings
44	All	Safety lock out	Check external control (room thermostat) requests Rapid on/off hot tap requests
46	All	External sensor intervention	Check external sensor and cable are not damaged or wet Check continuity of external sensor and circuit Check connection at X19 on PCB and sensor connecting block
47	All	Reduced burner output	Air in heat exchanger Restricted primary flow Heat exchanger air flow blocked Flue restriction Flue sensor fault Pump fault
51	All	Climatic RF communication fault	Batteries require replacing Distance between boiler and climatic control too great Interference Object blocking signal (metallic)
59	All	Mains supply voltage frequency block	The PCB detects an incorrect mains supply Voltage frequency – Check mains power supply Faulty PCB
60	All	Pump fault	The pump is stuck or there is an electrical pump fault: Check the pump operation, it may be necessary to free the pump shaft Check the pump wiring Replace the pump
61	All	Air in the pump	Restricted CH flow due to air or a circuit restriction: Check Flow and Return valves are open Check for correct system pressure Check the system is purged properly
62	All	Full boiler calibration required	This may occur when the PCB is replaced or if the parameters are altered in the air/gas section: Carry out full calibration process as described
72	All	Fast calibration required	The PCB detects that some parameters have been altered Carry out fast calibration process as described
73	All	High flow NTC and safety NTC difference detected	The board detects an anomaly in the temperature readings difference between the flow NTC and safety NTC sensors Faulty flow or safety NTC sensor Check resistance reading on the sensors Poor system circulation or blockage
74	All	Safety flow sensor anomaly	The PCB detects an anomaly on the safety NTC sensor: Faulty safety NTC sensor Check resistance reading on sensor Replace the safety NTC sensor
77	All	An anomaly on the gas valve control is detected	An anomaly on the gas valve control is detected Check the electrode condition, replace if necessary Check the inlet gas pressure is correct and carry out a full calibration process as described. If the fault persists replace gas valve
78	All	An anomaly on the gas valve control is detected	An anomaly on the gas valve control is detected Check the electrode condition, replace if necessary Check the inlet gas pressure is correct and carry out a full calibration process as described. If the fault persists replace gas valve
79	All	An anomaly on the gas valve control is detected	An anomaly on the gas valve control is detected Check the electrode condition, replace if necessary Check the inlet gas pressure is correct and carry out a full calibration process as described. If the fault persists replace gas valve
No lights on	Alpha C23, C27 CB, CB50, CD50, CDC, CDR, CDS, CDX, HE, HECB, HESY	Electricity fault	Check your electricity supply
Illuminated red A or B	Alpha C23, C27 CB, CB50, CD50, CDC, CDR, CDS, CDX, HE, HECB, HESY	Burner has failed to light	Rotate selector switch to the reset position (3) and the ignition sequence will restart after a delay of about 30 seconds
Illuminated yellow B or C	Alpha C23, C27 CB, CB50, CD50, CDC, CDR, CDS, CDX, HE, HECB, HESY	Burner is alight	No action required
Flashing red A or B	Alpha C23, C27 CB, CB50, CD50, CDC, CDR, CDS, CDX, HE, HECB, HESY	Overheat thermostat has operated / Temperature sensor fault	Rotate selector switch to the reset position (3) to reset
Flashing yellow every five seconds or Illuminated Green D	Alpha C23, C27 CB, CB50, CD50, CDC, CDR, CDS, CDX, HE, HECB, HESY	Electrical supply to the boiler is on	No Action Required
Flashing yellow B or flashing Red A	Alpha C23, C27, CB, CB50, CD50, CDC, CDR, CDS, CDX, HE,HECB, HESY,	Temperature sensor fault	Contact a professional
Illuminated red A and flashing yellow B or Flashing red A and flashing red B	Alpha C23, C27, CB, CB50, CD50, CDC, CDR, CDS, CDX, HE,HECB, HESY,	Blocked flue or fan fault	contact a professional
Flashing yellow or flashing Red A or Flashing (alternating) red A and flashing (alternating) yellow B	Alpha C23, C27, CB, CB50, CD50, CDS, CDX, HE,HECB, HESY,	System pressure is very low and re-pressurisation is required	Contact a professional
Illuminated red A and flashing yellow B	Alpha C27, CB, CB50, HE,HECB	Pump fault or restricted flow	Contact a professional
Flashing red A and Flashing red B and flashing yellow C	Alpha CDR	Temperature sensor wiring or flow and return connections incorrect	Contact a professional
Flashing red A and flashing red B and flashing yellow C indicators	Alpha CDS, CDX	Flue temperature too high (air in the heat exchanger, heat exchanger blocked	Contact a professional

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