Performed yearly maintenance and safety checks on 2016 Bryant 80% down flow furnace. Found ignition system reading 54 ohms. 73 degree RA. 97 degree SA. 24 degree delta t On low fire. Manufacture specifies 20-50 low fire. 30-60 high fire. Running 53 degree delta t on high fire. Found no concerns with heating system. Left new 14201 filter..