6.2.10 Boiler treatment 69
6.2.11 Relief valve - maintenance and testing 69
6.3 Replacing the fan, gas valve, and burner 70
6.3.1 Replacing the fan 71
6.3.2 Replacing the gas valve 72
6.3.3 Replacing the burner 74
6.4 Replacing the air filter 76
6.5 Cleaning a condensate trap 77
7.1 Preliminary checks 79
7.2 Electronic components 80
7.2.1 Temperature sensors 80
7.2.3 Air pressure sensor 81
7.2.4 Water pressure sensor 81
7.2.5 Gas pressure switches 82
7.2.6 Safety and Ignition Module (SIM) 82
7.3 Troubleshooting error messages 85
7.3.1 Touchscreen error messages 85
7.3.2 Maximum ignition trials error 86
7.3.3 Hi/Low gas pressure switch error 87
7.3.4 Hi Limit cut-off temperature error 87
7.3.5 Low Water Cut-off error 87
7.3.6 Aux. Interlock 1 or 2 88
7.4 Miscellaneous touchscreen controller errors 88
7.4.2 Temperature issues 90
7.4.3 Miscellaneous issues 91