Preventative maintenence inspection on three Trane high efficiency gas furnaces running in great condition. All three air filters replaced today. Replaced humidifier pad on main system humidifier. Calcium clogged humidifier pad was causing water leak. Cleaned flame sensors and checked ignitors. Visual inspection of burners. Flush condensation traps and drain lines. Run test each system in heating mode from thermostat. All systems are operating within specifications for temperature rise, blower Amp draw, inducer Amp draw, and gas pressures. Pvc flue vents are in good condition and no sign of leaks. 0PPM CO detected during testing. Run test humidifier to ensure no leaks. All systems are operating properly, efficiently and ready for Winter.