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Honeywell VisionPro IAQ Thermostat (TH9421C1004)

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Honeywell VisionPro IAQ Thermostat (TH9421C1004) with no interface module.  For use with Honeywell Envirazone Systems.


The VisionPRO IAQ touchscreen universal programmable thermostat provides electronic control of 24 Vac heating and cooling systems in addition to humidification, dehumidification and ventilation all with just 3 wires to the thermostat.


. 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.


Description  VisionPRO® IAQ Touchscreen 7-Day Programmable Thermostat. Total Home Comfort System with Temperature, Humidification, Dehumidification and Ventilation Control
Application  Conventional and Heat Pump systems
Programmability  7 Day Multiple Day Programming or Non-Programmable
Changeover  Auto/Manual Selectable
Color  Premier White®
Switch Positions (System)  HEAT-OFF-COOL-AUTO-EM.HEAT
Switch Positions (Fan)  AUTO-ON-CIRC
Power Method  Communicating
Terminal Designations  1, 2, 3
Dimensions (in.)  4 9/16 in. high x 6 in. wide x 1 1/4 in. deep
Dimensions (mm)  116 mm high x 152 mm wide x 32 mm deep
Mounting  Horizontal
Electrical Ratings  THM5421 is rated 20 to 30 Vac
Setting Temperature Range (F)  Heat: 40 F to 90 F; Cool 60 F to 99F
Setting Temperature Range (C)  Heat: 4.5 C to 32 C; Cool: 15 C to 37C
Differential Temperature (F)  ± 1 F
Differential Temperature (C)  ±0.5 C
Stages  Up to 4 Heat/2 Cool Heat Pump
Stages  Up to 3 Heat/2 Cool Conventional
Outdoor Sensor  Yes, optional
Discharge Sensor  Yes, optional
Remote Sensor  Yes, optional
Sensor Element  Thermistor
Operating Humidity Range (% RH)  5 to 90% RH, non-condensing
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.
Used With  THM5421C1008 Equipment Interface Module
Display Size  10 sq. in.
Humidification Setting Range  10 to 60% RH.
Dehumidification Setting Range  40 to 80% RH.
Voltage  20 to 30 Vac