Common Boiler Problems
Keston Boilers
As professional Gas Safe Register installers for Keston gas boilers and OFTEC registered installers for Keston oil-fired boilers throughout north London, BBS Plumbing and Heating are also are fully qualified and experienced to service, upgrade and repair all Keston boiler types, and carry out repairs to existing hot water and central heating systems.
Fault finding main menu.
Combi Boilers – Combi 30 / Combi 35
Boiler status display information is shown – up to six messages in rotation
– as described below:
| Fault | Remedy |
|---|---|
| Overheat lockout | 1 Fill system to 1.0 bar; 2 Bleed radiators; 3 Check radiator valves open; 4 Reset boiler; 5 Contact installer |
| Ignition lockout / Flue Overheat | 1 Check other gas appliances work; 2 Reset boiler; 3 Contact Installer |
| Too many resets | Contact Installer |
| Fault 8 | Contact Installer |
| Low water pressure | 1 Fill system to 1.0 bar; 2 Bleed radiators; 3 Contact installer |
| Flame loss | 1 Check other gas appliances; 2 Contact installer |
| Fan fault | Contact Installer |
| Return thermistor fault | Contact Installer |
| Outside sensor fault | Contact Installer |
| Low mains voltage | Contact electricity provider |
| PCB Fault | Contact Installer |
| PCB Replaced | Reset boiler |
| Flow thermistor fault | Contact Installer |
| Boiler Chip Card Fault | Contact Installer |
| 12 month service interval request | Contact Installer |
Please Note: The above information is for guidance only. You will need to call an qualified and experienced Gas Safe Keston service engineer, such as BBS Plumbing and Heating, for further advice.
Combi Boilers – C36 / C36P
Fault Modes
If a situation is detected, which the boiler considers may cause damage to the appliance the boiler will enter a lockout mode and stop functioning. After clearing the problem the “reset” button must be pressed once to resume boiler operation.
Please note :Switching the power ON and then OFF will not clear a boiler lockout.
Error Codes
| Display | Description of fault | |
|---|---|---|
| E01 | Ignition failure – the boiler has attempted to light five times and not succeeded. | |
| E02 | False flame – the unit is detecting a flame BEFORE ignition. | |
| E03 | Boiler overheat. | |
| E05 | Fan failure – boiler cannot detect fan rotation. | |
| E07 | Flue overheat. | |
| E08 | Flame circuit error – possible control box fault. | |
| E09 | Valve drive error – possible gas valve or control box fault. | |
| E10 | Control box errors – possible faulty control box. | |
| E11 | The automatic test for calibration of flow and return sensors has failed. | |
| E12- E22 | Control box errors – possible faulty control box. | |
| E23 | Water filling error. | |
| E24 | Water pressure lost 4 times in 24 hours – possible leak. | |
| E25 | Control box errors – possible faulty control box. | |
| E26 | Flame signal lost 5 times in 4 minutes – the flame is unstable. | |
| E30 | Flow sensor short circuit. | |
| E31 | Flow sensor short circuit. | |
| E32 | DHW sensor short circuit. | |
| E33 | DHW sensor short circuit. | |
| E34 | Mains supply voltage < 180V.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-yiz08m'][av_cell col_style='' av_uid='av-yaaqq6']E35[/av_cell][av_cell col_style='' av_uid='av-y3hexq']Mains supply frequency incorrect.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-y11h1i'][av_cell col_style='' av_uid='av-xrnty6']E37[/av_cell][av_cell col_style='' av_uid='av-xpqjcm']Water pressure error.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-xgvlva'][av_cell col_style='' av_uid='av-xcxdhy']E38[/av_cell][av_cell col_style='' av_uid='av-x4nooe']Reset key fault – replace fascia PCB.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-wy9c8m'][av_cell col_style='' av_uid='av-wvimzy']E40[/av_cell][av_cell col_style='' av_uid='av-wo855i']Water pressure too high.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-wiw546'][av_cell col_style='' av_uid='av-wcmrou']E41[/av_cell][av_cell col_style='' av_uid='av-w7ayli']Communication error between fascia and control box.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-37bb0u'][av_cell col_style='' av_uid='av-vu9e9y']E43[/av_cell][av_cell col_style='' av_uid='av-3647bq']Return sensor short circuit.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-vjnbna'][av_cell col_style='' av_uid='av-vcybpy']E44[/av_cell][av_cell col_style='' av_uid='av-v79eem']Return sensor short circuit.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-v2vlum'][av_cell col_style='' av_uid='av-ut4od2']E45[/av_cell][av_cell col_style='' av_uid='av-uo3uby']Flue sensor short circuit.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-uhz4ce'][av_cell col_style='' av_uid='av-uajp12']E46[/av_cell][av_cell col_style='' av_uid='av-u4v426']Flue sensor short circuit.[/av_cell][/av_row]
[av_row row_style='' av_uid='av-u0t346'][av_cell col_style='' av_uid='av-tthzny']E99[/av_cell][av_cell col_style='' av_uid='av-trh7am'] Communication error between fascia and control box.[/av_cell][/av_row]
[/av_table]
[av_textblock size='' font_color='' color='' av_uid='av-tl2u32']
Please Note: The above information is for guidance only. You will need to call an qualified and experienced Gas Safe Keston service engineer, such as BBS Plumbing and Heating, for further advice.
Combi Boilers – C45 / C40P / C55 / C55P Fault Modes Automatic Lockout Avoidance The boiler will react to adverse conditions in two ways. If the fault is not severe, or is not persistent, the boiler will halt (or block) operation for a set time before it attempts to fire again. Block Codes | Reason for Block |
| B 18 | Flow temperature exceeds 95 deg C | |
| B 19 | Return temperature exceeds 95 deg C | |
| B 24 | Return temperature exceeded flow temperature. | |
| B 25 | Flow temperature climbing too quickly – possible airlock or circulation blockage. | |
| B26 | Low water pressure. | |
| B28 | No signal from fan – possible fan disconnected or faulty. | |
| B29 | Incorrect signal from fan – possible fan faulty. | |
| B 30 | Difference between flow and return temperatures too high. | |
| B 65 | Waiting for fan to start. |
Lockout
If the fault is persistent or more severe the boiler will lockout with a error code. When the boiler has entered this error mode it will not attempt to restart until the “Reset” button is pressed.
Error Codes
| Display | Description |
|---|---|
| E 00 | Flame detected when not expected. |
| E 02 | No ignition after restart. |
| E 03 | Gas valve faulty or not connected. |
| E 04 | Power has been reset whilst boiler was in lockout. |
| E 11 | Internal electronics error. |
| E 12 | Thermal fuse blown or flue overheat thermostat activated. |
| E 18 | Flow overheat. |
| E 19 | Maximum return temperature exceeded. |
| E 25 | Flow temperature increased too quickly. |
| E 28 | Fan not rotating. |
| E 30 | Difference between flow and return temperatures too high. |
| E 31 | Flow thermistor short circuit. |
| E 32 | Return thermistor short circuit. |
| E 36 | Flow thermistor short circuit. |
| E 37 | Return thermistor short circuit. |
| E 44 | Low water pressure. |
Please Note: The above information is for guidance only. You will need to call an qualified and experienced Gas Safe Keston service engineer, such as BBS Plumbing and Heating, for further advice.
System Boilers
System 30
Basic Troubleshooting
| NO Central Heating or NO Hot Water | |
|---|---|
| STEP 1 | Check the mains switch (fused spur) is turned on and ensure mode control knob (B) is in the ON position. |
| STEP 2 | Check the programmer is at the “ON” position and the room thermostat is turned up. |
| STEP 3 | Does the boiler operate an provide central heating? YES – Check the time settings on the programmer are as required and adjust if necessary. NO – See boiler “Fault Codes” section. If “0” is displayed then contact a Gas Safe Registered Engineer for further advice. |
Please Note: The above information is for guidance only. You will need to call an qualified and experienced Gas Safe Keston service engineer, such as BBS Plumbing and Heating, for further advice.
Fault Codes
| Display Code | ||
|---|---|---|
| Status | Status | Fault |
| F | 0 | Boiler Chip Card (BCC) not fitted. |
| F | 6 | Outside sensor failure. Reset the appliance – if the boiler fails to operate then please contact Keston (if under warranty) or alternatively a Gas Safe Registered Engineer. |
| F | 7 | Low Mains Voltage. |
| F | 9 | PCB Fault. |
| L | 5 | 5 Boiler Resets in 15 minutes – Turn power off and on at the fused spur. |
| L | 6 | False Flame Lockout. |
| C | 0 | BCC Activation Fault. |
| C | 2 | BCC Fault. |
| F | 1 | Low Water Pressure – Check system pressure is between 1 and 1.5 bar on the pressure gauge. |
| L | 1 | Flow Temperature Overheat – Check system pressure is between 1 and 1.5 bar on the pressure gauge. |
| F | 2 | Flame Loss – Check other gas appliances in the house are working to confirm a supply is present in the property. If other appliances do not work or there are no other appliances check the gas supply is on at the meter and/or pre payment meter has credit. |
| L | 2 | Flame Loss – Check other gas appliances in the house are working to confirm a supply is present in the property. If other appliances do not work or there are no other appliances check the gas supply is on at the meter and/or pre payment meter has credit. |
| F | 3 | Fan Fault – Reset the boiler. |
| F | 4 | Control / No Flow Thermistor – Reset the boiler. |
| F | 5 | Return Thermistor – Reset the boiler. |
Please Note: The above information is for general guidance only. If a reset of the boiler fails to clear the fault code and the boiler fails to operate then please call a qualified and experienced Gas Safe Keston service engineer, such as BBS Plumbing and Heating, for further advice.
Your privacy is of paramount importance and your details are not passed onto third parties but held in strict confidence.
