Honeywell VisionPRO® IAQ Total Home Comfort System


The VisionPRO IAQ touch screen universal programmable thermostat provides electronic control of 24 Vac heating and cooling systems in addition to humidification dehumidification and ventilation.
• 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.
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Cat # | Application | Stages | Switch Position |
TH9421C1004 | Conventional and Heat Pump systems | Up to 3 Heat/2 Cool Conventional. Up to 4 Heat/2 Cool Heat Pump | HEAT-OFF COOL- AUTO EM. HEAT |
THM5421C1008 | Heat/Cool or Heat Pump with Auxiliary Heat | Up to 3 Heat/2 Cool Conventional. Up to 4 Heat/2 Cool Heat Pump | HEAT-OFF COOL- AUTO EM. HEAT |
YTH9421C1002 | Heat/Cool or Heat Pump with Auxiliary Heat | Up to 3 Heat/2 Cool Conventional. Up to 4 Heat/2 Cool Heat Pump | HEAT-OFF COOL- AUTO EM. HEAT |
YTH9421C1010 | Heat/Cool or Heat Pump with Auxiliary Heat | Up to 3 Heat/2 Cool Conventional. Up to 4 Heat/2 Cool Heat Pump | HEAT-OFF COOL- AUTO EM. HEAT |
Dimensions, Approximate: | 9/16 in. high x 6 in. wide x 1 1/4 in. deep (116 mm high x 152 mm wide x 32 mm deep) | ||
Programmability: | 7 Day Multiple Day Programming or Non- Programmable | ||
Differential Temperature: | ± 1 F (± 0.5 C) | ||
Power Method: | Communicating | ||
Sensor Element: | Thermistor | ||
Electrical Rating: | THM5421 is rated 20 to 30 Vac | ||
Changeover: | Auto/Manual Selectable | ||
Comments: | Includes Humidification Control with or without Frost Protection, Dehumidification using Whole House Dehumidifier or Air Conditioning with High or Low speed fan, Advanced Patented Ventilation Control and Advanced Dual Fuel Heat Pump Control. | ||
Color | Premier White® | ||
Mounting | Horizontal |