Performed preventative maintenance for a Lennox system model #G61MPV-60C-111-12, serial #5910F25275 located in the basement. Powered down the system and removed the access panels. Removed and cleaned carbon off of the flame sensor, cleaned out the burners and burner box. Checked all electrical connections to ensure that they are secure and in good condition. Replaced the air filter size 16x25x1. Cleaned out the condensate trap and tested the drain line and condensate pump with several bottles of water. Powered the system back up and called for heat. Took a combustion analysis test and got the following readings, o2 is at 12.9%, co is at 7ppm. The inducer amp draw is at .5 and the blower motor amp draw is at 8.7. The supply temp is at 115°F. The system is operating properly at this time. Performed preventative maintenance for a Lennox system model #SL280UH070V36A-05, serial #5916L11243. Powered down the system and removed the access panels. Removed and cleaned carbon off of the flame s