Performed comprehensive maintenance on 17-year-old FRP furnace system (manufactured 2004, installed 2008). Inspected heat exchanger (noted rust on eyelid), tested carbon monoxide levels (acceptable readings), and checked gas pressure. Adjusted low stage gas pressure from 8.3" WC to 1.7" WC. Attempted to adjust high stage pressure from 10.8" WC to 3.5" WC but could only reduce to 5.3" WC due to possible stuck valve spring. Advised homeowner of issues and prepared quotes for gas valve replacement, UV light bolt replacement, and solenoid humidifier replacement.
