VisionPRO® IAQ is everything that you love about VisionPRO® and so much more. Use it for every job where you need to: Upgrade to Multi-Stage Equipment — Save time, money and hassle. There’s no need to pull additional wires through the wall to connect the thermostat in the living space. Three wires are all you need, and everything else wires through an Equipment Interface Module at the equipment. Add Air Quality Enhancements Without Wall Clutter — VisionPRO IAQ gives you all-in-one control for temperature, humidification, dehumidification and ventilation systems — eliminating the need for multiple controls in the living space. Everything can be managed from a single, effortless, touchscreen control. Eliminate the Need for a Fossil Fuel Kit — VisionPRO IAQ has a built-in fossil fuel kit. It practically pays for itself versus buying a kit. Display Outdoor Temperature — Use our outdoor temperature sensor to display outdoor temperature on the thermostat. Sensor included with YTH9421C1010 model. Reduce Inventory — VisionPRO IAQ is universal and works with almost every brand of heating/cooling equipment up to 3 Heat/2 Cool conventional and 4 Heat/2 Cool heat pump with two stages of auxiliary heat. Quiet Operation — All relays are housed in the Equipment Interface Module at the equipment, eliminating the clicking noise commonly heard at thermostats in the living space