Honeywell YTH9421C1002 White VisionPro IAQ Total Home Comfort System

- Item #: BCI1249250

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Questions about Honeywell YTH9421C1002?

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  • 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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