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Item#: 9SIA1ZR0UN0042

Honeywell VisionPro IAQ Thermostat (TH9421C1004)

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Honeywell VisionPro IAQ Thermostat (TH9421C1004) with no interface module. For use with Honeywell Envirazone Systems.DOES NOT INCLUDE EQUIPMENT INTERFACE MODULEThe 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.Features: 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.Specifications: Description VisionPRO IAQ Touchscreen 7-Day Programmable Thermostat. Total Home Comfort System with Temperature, Humidification, Dehumidification and Ventilation ControlApplication Conventional and Heat Pump systemsProgrammability 7 Day Multiple Day Programming or Non-ProgrammableChangeover Auto/Manual SelectableColor Premier WhiteSwitch Positions (System) HEAT-OFF-COOL-AUTO-EM.HEATSwitch Positions (Fan) AUTO-ON-CIRCPower Method CommunicatingTerminal Designations 1, 2, 3Dimensions (in.) 4 9/16 in. high x 6 in. wide x 1 1/4 in. deepDimensions (mm) 116 mm high x 152 mm wide x 32 mm deepMounting HorizontalElectrical Ratings THM5421 is rated 20 to 30 VacSetting Temperature Range (F) Heat: 40 F to 90 F; Cool 60 F to 99FSetting Temperature Range (C) Heat: 4.5 C to 32 C; Cool: 15 C to 37CDifferential Temperature (F) ± 1 FDifferential Temperature (C) ±0.5 CStages Up to 4 Heat/2 Cool Heat PumpStages Up to 3 Heat/2 Cool ConventionalOutdoor Sensor Yes, optionalDischarge Sensor Yes, optionalRemote Sensor Yes, optionalSensor Element ThermistorOperating Humidity Range (% RH) 5 to 90% RH, non-condensingComments 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 ModuleDisplay Size 10 sq. in.Humidification Setting Range 10 to 60% RH.Dehumidification Setting Range 40 to 80% RH.Voltage 20 to 30 Vac



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  • Limited Warranty period (parts): 1 year
  • Limited Warranty period (labor): 1 year

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  • Jimmy B.
  • 12/31/2013 6:10:22 PM
  • Tech Level: Average
  • Ownership: 1 week to 1 month
  • Verified Owner

5 out of 5 eggsWorks great

Pros: Easy installation, easy to use

Cons: none

Other Thoughts: Not much to say. This purchase was the replacement of an identical thermostat installed by my HVAC contractor 5 years ago, so I purchased another one after my old one stopped working properly. The new unit works the same as the old one which I liked very well.

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Item#: 9SIA1ZR0UN0042
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