Performed yearly maintenance and safety checks on 2015 rheem furnace.customer replaced her own water panel. Blew out water trap. Cleaned flame sensor. 7.5 voltage absorption system reading 7.3. Made call for heat. Found 9.77%o2. 27 ppm co in flu 0 ppm co in supply. 55 degree deltat. Customer also inquired about water heater left quote. Will talk to husband and get with office to schedule if need be