System #1- Whole house system. Performed preventative maintenance for a Lennox furnace model #SL280UH090V48B-03, serial #5914K18758. I powered the system down and removed the access panels. I removed and cleaned carbon off of the flame sensor and cleaned out the burners and burner box. Replaced the air filter size 16x25x5 and Checked the pressure switch for clogs. Checked all electrical connections to ensure that they are secure and in good condition. Performed humidifier service for a Aprilaire 600 series humidifier. I removed and replaced the old #35 water panel. Cleaned out the housing and drain. Set the dampener for winter and set the humidistat for test. I powered the system back up and called for heat. Took a combustion analysis test and received the following readings, o2 is at 10.4% and the co levels are 12ppm. The inducer motor amp draw is at .21 and the blower motor amp draw is at 7.6. Tested the humidifier for proper operation and leaks. Performed preventative maintenance