Prestige IAQ Comfort System Kit (Includes Thermostat, EIM & 2 Duct Sensors) Zoom

Prestige IAQ Comfort System Kit (Includes Thermostat, EIM & 2 Duct Sensors)


Brand: Honeywell

YTHX9421R5051 has been discontinued.
Direct Replacement:
SKU: YTHX9421R5085WW
Brand: Honeywell



Application: Multi Stage (Heat/Cool)
Heat Pump
4 Heat/2 Cool Heat Pump
3 Heat/2 Cool
Programmability: Programmable
7 Day
User Interface: Touchscreen
Features: Humidification & Dehumidifcation Control
RedLINK Enabled
Ventilation Control
Power Method: Hardwired
Changeover: Manual
Temperature Range (F): 40°-99°F
Operating Temp Range: 32°-120°F
18/30 VAC
Color: Arctic White
Mount: Horizontal
Options: Auto Changeover
Fan Control
Large Display
Comes with Sensor

Description for Honeywell YTHX9421R5051


  • Kit Includes:
    • Prestige IAQ Thermostat (THX9421R5013 )
    • Equipment Interface Module (THM5421R1013 )
    • 2 C7735A1000 Duct Sensors
  • RedLINK Enabled
  • 7 Day Program
  • Up to 4H/2C Heat Pump
  • Up to 3H/2C Conventional
  • Controls Humidification, Dehumidification and Ventilation
  • Large, easy-to-read full color display shows current indoor temperature and humidity, temperature setting, date and time on the home screen. Also displays outdoor temperature and humidity on home screen (if wireless outdoor sensor is installed)
  • Controls multistage equipment, humidification, dehumidification and ventilation all with only 2 wires at the thermostat location
  • Customizable Service Reminders allows the contractor to have automated messages direct homeowners to a screen with the contractor's full-color company logo, phone number and website
  • Change Reminders to inform it is time to replace air filter, humidifier pad or ultraviolet bulb or batteries in RedLINK connected devices
  • Adjustable backlight level allows thermostat to be on full brightness at all times or dim to the brightness level of choice when the thermostat is not being used
  • Interview-Based Programming wizard to easily and confidently schedule thermostat temperature and times
  • USB Port allows downloading of installer settings to quickly and consistently perform setup of thermostats in similar applications
  • USB Port allows easy setup of dealer logo and contact information on thermostat screen
  • Real-Time Clock keeps time during power failure; automatically updates for daylight saving time
  • Precise Temperature Control (± 1°F) for reliable and consistent temperature
  • Multiple HOLD options allows modification of schedule as needed
  • RedLINK Enabled to communicate with compatible wireless devices

Prestige IAQ Comfort System Kit (Includes Thermostat, EIM & 2 Duct Sensors)


by PowerReviews

(based on 4 reviews)

Ratings Distribution

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  • 1 Stars




of respondents would recommend this to a friend.

Reviewed by 4 customers

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(1 of 1 customers found this review helpful)


Form and Function

By BrianS

from Boston MA

Verified Buyer

This product performs exactly the way it supposed to. Once professionally installed the menu for the consumer to set up and download to an iphone is very simple. The best part is the product works well. In addition the product looks awesome. The backlight and colors stay lit for easy viewing.

(1 of 1 customers found this review helpful)


Amazing Thermostat

By Andy B

from Cincinnati, OH

Verified Buyer

I purchased two of these thermostats to control my two heat pump system. Setup was very simple and much more intuitive than the Vision Pro 8000s these replaced. One of the main reasons I purchased these was to have the humidifiers controlled by the thermostat and adjusted based on ambient conditions. After a few weeks of service, I could not be happier with the setup. There is a great deal of flexibility to accomodate nearly every HVAC system, and the intuitive menus give you visibility into what your system is doing (what components are running, change in temperature, etc). There are also nice built in features for overriding the schedule (stay home from work, scheduled exceptions). Great thermostat, great pricing, and quick shipping. Highly recommended.


Prestige IAQ

By Scott

from Colorado

Verified Buyer

This thermostat does it all. Easy to install and easy to operate. Uses just two wires for the thermostat so now I can use my two stage heat and 1 stage cool. You can even program the screen for different colors to match the decor. The wireless outdoor sensor hooked right up.


Excellent Thermostat

By dmccutch

from Waterloo, Ontario

Verified Buyer

Fairly easy to install if you have a basic understanding of wiring.

Programming it is fairly straight forward, and I have it working well with a humidifier and a high efficiency gas furnace.

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2 Questions | 3 Answers
Displaying questions 1-2
  • Q:

    Can the YTHX9421R5051 be used in a dual fuel application?
    (Gas furnace with a heat pump)
    Asked on 7/20/2012 by Distributor from Wichita, Ks

    1 answer



      Yes, it should work fine for any multi-stage set ups.

      Answered on 7/23/2012 by PexSupply Staff from NY
  • Q:

    Is this the 2.0 thermostat package?
    Asked on 2/29/2012 by Anonymous

    2 answers



      Yes, part YTHX9421R5051 is a Prestige 2.0 IAQ kit. It includes a THX9421R5013 thermostat, a THM5421R1013 equipment interface module, and two duct sensors for diagnostics.

      Answered on 2/29/2012 by PexSupply Staff from NY


      Yes, includes the duct sensors.

      Answered on 4/25/2012 by Scott from Colorado
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