Performed heating maintenance on a Tempstar 80% efficient two stage natural gas furnace. Replaced air filter Pulled and cleaned flame sensor Verified control board setup switches for airflow settings and adaptive two stage operation with a single stage thermostat Gas pressure for high fire set to 3.2" and has a 48 degree temperature rise. Gas pressure for low fire set to 1.6" and has a 43 degree temperature rise. Ran furnace for an extended period to be sure no high temperature limit trips. All electrical components test within manufacturer's tolerances Wiring is all tight and secure, no visual signs of overheating or fraying. No carbon monoxide detected in supply or return ductwork Blower wheel is clean and free of any debris