Perform Gold preventative maintenence inspection on two Carrier high efficiency furnaces. Both are operating in great condition. 20x25x4 air filter replaced on both units. Installed new humidifier water panel on main system. Replaced ERV filter set with filters on site. Clean flame sensors and check ignitors. Visual inspection of burners. Flush condensation traps and drain lines. Run test each system in gas heating mode. Both systems are operating properly and within specifications for temperature rise, blower and inducer motor amp draw, and manifold gas pressures. Test ran operation of geothermal heating. Did not check refrigerant as there are no issues suspected. Replaced 2X AA batteries in wireless outdoor temperature sensor. All systems are operating properly, efficiently and ready for Winter.