Step1: Turn off electrical power and gas supply to appliance before starting.
Step2: Remove access panel and carefully disconnect old thermostat wiring harness.
Step3: Label each wire clearly for correct reconnection later.
Step4: Mount new thermostat in original position and secure firmly.
Step5: Reconnect wiring according to labeled terminals and tighten connections.
Step6: Replace panel, ensure all fittings are tight and sealed.
Step7: Restore power and gas, test operation, and verify safety cutoff function.