| 10, 11,12, 13,14 | – CH Supply Sensor fault S1 | •Check wiring for break |
| | • Check for proper flow direction |
| | • Replace S1 |
| | • E10 open sensor •E11 Short sensor |
| 20, 21, 22, 23, 24 | – CH Return Sensor fault S2 | • Check wiring for break |
| | • Check for proper flow direction |
| | • Replace S2 |
| | • E 20 open sensor •E21 short sensor |
| 0 | – Sensor fault after self check | • Replace S1 and/or S2 |
| 1.28 | -Temperature too high | •Air in installation |
| | • Pump not running |
| | • Insufficient flow in installation, shut off valves closed, pump setting too low |
| | • Flow switch sticking or miss-installed |
| 2 | – S1 and S2 interchanged | • Check water flow |
| | • Check wiring |
| | • Replace S1 or S2 |
| 4 | – No flame signal | • Manual Gas shut off valve closed |
| | • No or incorrect ignition gap |
| | • Gas supply pressure too low of failling |
| | • Gas valve or ignition unit not powered |
| 5 | – Poor flame signal | • Condensate drain blocked |
| | • Check adjustment of gas valve |
| 6 | – Flame detection fault | • Replace ignition cable + spark plug cap |
| | • Replace ignition unit at gas valve |
| | • Replace boiler controller |
| 8 | – Incorrect fan speed | • Fan catching on casing |
| | • Wiring between fan and casing |
| | • Check wiring for poor wire contact |
| | • Replace fan |
| 29.3 | – Gas valve relay faulty | • Replace boiler controller |
| LOP | – Low CH system pressure | • Raise CH pressure above 7 psi [ 0.5 bar] |
| 3, 18, 19 | – Flue sensor Fault | •E18open sensor •E19 Short sensor |
| | • Check/ Replace sensor |
| | • E19 Excessive Temperature |
| | • Clean heat exchanger |
| 7.17 | – DHW sensor Fault | • E17 open sensor |
| | • Check/ replace sensor |
| | • E7 Excessive temperature |
| | • Check gas orifice |
| | • Check combustion settings |
| 50F | – Improper frequency | • Verify ground |
| | • Frequency should be between 45 and 65 Hz |