Performed heating maintenance on three Trane Gas fired, furnace, checked and clean burners and igniters and flame sensors. Also checked air pressure switch and replace Filters20+25-4 and 16+25+4 Two filters in total turn systems on and checked operations and natural gas lines also checked for carbon monoxide. None detected left systems, functional highly recommend for the second floor system to replace the igniter and the flame sensor. Model number D345884G04 View visual findings from this job here - https://visionshare.xoi.io/?id=XA-90AE-9DE0AE4DCE6B47F390BE86108AB78802