Honeywell YTH9421C1002 Visionpro IAQ Touch Screen 7-Day Programmable Thermostat, Version 2 Advanced dual-fuel control Three wires to the living space allows for easy equipment upgrade without having to run additional thermostat wire Thermostat connects with Equipment Interface Module or EnviraZONE panel to control temperature, humidification, dehumidification and ventilation from a single point in the home Automatically raises humidity levels throughout all rooms in the home, moisturizing air to prevent symptoms of dryness and to protect hardwood flooring and woodwork Removes air pollutants by exchanging the stale air in a house with fresh, filtered air better than having an open window