Honeywell YTH9421C1002 White VisionPro IAQ Total Home Comfort System

- Item #: BCI1249250
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Ambistat Temperature Controller

Control comfort and Indoor Air Quality (IAQ) throughout your entire home with Honeywell's VisionPRO IAQ Total Home Comfort System. VisionPRO IAQ eliminates the need for multiple controls in your living space, by managing your home's temperature, humidification, dehumidification and ventilation - all from a single, easy-to-use touchscreen control.

The TH9421U touch screen universal programmable thermostat provides electronic control of 24 Vac heating and cooling systems of 750 mV heating systems in addition to humidification dehumidification and ventilation.

  • Contains all features of standard VisionPRO, except arm chair programming.
  • 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.
  • Automatically lowers humidity levels through al rooms in the home, utilizing air conditioning or a whole house dehumidifier to prevent dampness, stickiness or odors; symptoms often associated with air that is too moist.
  • Removes air pollutants by exchanging the stale air in a house with fresh, filtered air better than having an open window.

Additional Honeywell Links

Our SKU: Honeywell YTH9421C1002

This product is listed under the following manufacturer number(s):

  • Honeywell YTH9421C1002

*Denotes a finish or option that has been discontinued

Honeywell YTH9421C1002 Product Specifications

Operating Manual
Installation Manual
Control Type Touch
Depth 1.25
Display Size 4
Hardwired No
Height 4.5625
Humidity Sensing Yes
Product Weight 3
Programmable Yes
Settings 6
Stages 4 Heat / 2 Cool
Supports Heat Pump Yes
Supports Millivolt No
Touch Screen Yes
UL Listed Yes
Voltage 20, 30
Width 6

Installation Resource Center

Whether you are installing the product yourself or hiring a professional, our installation Resource Center has everything you need to get your project done. Visit the Installation Resource Center to get started.

Honeywell YTH9421C1002 Reviews

  • Is this Thermostat & Equipment Interface Module compatible with zone controls?

    A. The Honeywell YTH9421C1002 is compatible with zone controls.
  • OPERATING MANUAL FOR Honeywell YTH9421C1002 VisionPro IAQ Total Home Comfort System

    A. The Honeywell YTH9421C1002 operating manual can be found on Honeywell's website here: I hope this helps!
  • If my system already has a Honeywell TH8110U1003 can I simply replace the thermostat with the YTH9421C1002 and run my system and humidifier as well or do I have to install the new thermostat beside the original one?

    A. The Honeywell YTH9421C1002 is compatible with the TH8110U1003. The included control module will need to be installed as well as changing to the new wall plates.
  • When used for humidification control, is this product also compatible with C7089U1006 (external temp sensor)? Also, does that external temperature sensor get wired to the EIM, or does it have to be wired directly to the thermostat?

    A. The Honeywell YTH9421C1002 Total Home Comfort System is compatible with the C7089U1006 Remote Outdoor Temperature Sensor, which would need to be wired in to the out 1 and out 2 inputs of the EIM (Equipment Interface Module) as it cannot be wired directly into a thermostat.
  • Will this system replace the pc8900 thermostat and perfect climate control system?

    A. The Honeywell YTH9421C1002 does not replace the pc8900

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