Completed one system furnace repair and preventative maintenance check. Changed filter. Dusted out and wiped down furnace cabinet. Cleared barometric tubing. Cleaned inducer port and pressure switch port. Tested mechanical and electrical components and found no issues. Performed combustion analysis and found good co and oxygen levels. Recommend secondary water safety to protect furnace from water damage in the event of a backed up drain line. Recommend apco air purifier to kill and prevent bacteria, germs, viruses and volatile organic compounds. The system is heating normally at this time.