Preventative maintenence inspection on three units. One geothermal and two gas furnaces. Geothermal unit is in clean condition. Air filter is in decent condition, check again in 1-1-2 months. Test ran operation through Aurora Aid Tool. Tested operation of electric strip heat and geothermal heating. All tested withing specifications. Two gas furnaces are operating in good condition. Air filters are in clean condition. Cleaned flame sensors and checked ignitors. Visual inspection of burners. Galvanized B-vents are in good condition. 0PPM CO detected during testing. Test ran each furnace in heating mode from thermostats. Both are operating properly and within specifications. All systems are operating properly, efficiently and ready for Winter.