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

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


Brand: Honeywell

YTHX9421R5077 has been discontinued.
Direct Replacement:
Brand: Honeywell



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

Description for Honeywell YTHX9421R5077


  • Kit Includes:
    • Prestige IAQ Thermostat (THX9421R5013 )
    • Equipment Interface Module (THM5421R1013 )
    • 2 C7735A1000 Duct Sensors
    • REM5000R1001 Portable Comfort Control
    • C7089R1013 Wireless Outdoor Temperature Sensor
  • RedLINK Enabled
  • 7 Day Program
  • Up to 4H/3C Heat Pump
  • Up to 3H/2C Conventional
  • Controls Humidification, Dehumidification and Ventilation
  • Wireless outdoor sensor
  • Portable comfort control
  • 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 & Portable comfort control)


by PowerReviews

(based on 3 reviews)

Ratings Distribution

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  • 1 Stars




of respondents would recommend this to a friend.

Reviewed by 3 customers

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Next Gen Thermostat

By jkmw

from Rockville, MD

Verified Reviewer



      Best Uses

        Yes, it is easy to install....But! as others have suggested, Know your existing system before you start; heat stages, cool stages, fan, common, etc. The connectors are flawless and the setup instructions are perfect but must be followed step by step. It's a two hour job max and I even ran a new wire through the wall for power to the screen/display. All wireless devices installed first time; outdoor sensor, remote comfort control, and optional indoor sensor.

        Having said all that positive stuff, I was dismayed to discover that the HD color display was defective. Pex Supply agreed on my word alone and sent out a new display. Turns out the original display in this kit is discontinued! And Pex Supply sent the new version display! Switching thermostats gave me way loads more trouble than the original install but after a thorough search through the new install manual, I found the answers and all is up and running once again.

        Please be advised, This kit contains both an EIM and thermostat display that Honeywell no longer supplies. The display screen is virtually identical in size but the case is much more compact. The new EIM provides additional inputs for dry contact sensors but is otherwise the same. I had no use for these so I did not press the point. I got the new screen, which by the way is much brighter and even seems clearer...more HD, and I'm happy.

        Last, I opted for the Redlink Internet Gateway and am having a great deal of fun with it. The wireless connection to the thermostat is the same as for all the other accessories and is flawless. The website setup is cumbersome but doable. I've set up a host of email addresses to which the gateway will send customizable alerts and all the settings are adjustable. Ok, but so what. I set the cool back during the day, but not too far as I have Huskies, and I suppose I could crank it back down (summer) or up (winter) if I went home sick or left early from work. It's a great idea, and it works, but I don't really need it.

        • Was this a gift?:
        • No

        Excellent Product

        By Fpresto

        from Maryland

        Verified Buyer

        Lots of advantages to this system. Only needs two wires. Wireless connectivity to the outside sensor. Able to control via phone or computer. If you have a dual fuel system it eliminates the need forn an external dual fuel controller. Highly recommended.

        (1 of 1 customers found this review helpful)



        By TFD

        from Memphis, TN.

        Verified Buyer

        This Honeywell product was very easy to install and set up, however I would STRONGLY recommend that you READ ALL the installation and operating material provided by Honeywell before you begin. If you don't understand something about the installation procedure DON'T PROCEED until you have a complete understanding of what you are doing. In other words, don't just guess. If you are not familiar with I.T., networking, wifi then I would recommend getting some help.
        The system works so well that it will be THE way to control the HVAC in homes and offices going forward.
        Now for some good purchasing advice. I made the mistake of ordering this product from another online seller. The problem with that seller is it would show back ordered AFTER you ordered it. They strung me along for an entire month! I found PEX SUPPLY on the web, called them and talked to some very nice people . I explained my situation, they met the other company's price and shipped it IMMEDIATELY!!
        PEX SUPPLY is the ONLY company I will deal with in the future. They actually care about the customer.

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        Q&A: Ask the Questions, share answers

        Do you have questions about this product?

        get answers from real customers and in-house experts with AnswerBox.

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

          What thermostates do I use with a home with multiple zones?
          Asked on 8/9/2012 by D from olean, NY

          1 answer

          • CUSTOMER CARE


            It depends on what the zone panel is that is used and the application being controlled. If there are existing thermostats installed, look at the wiring of the thermostats to determine the proper replacement.

            For hot water heat only, the thermostats would typically use just R and W or R, W, and Y. The TH5110D, TH6110D, or TH8110U models are commonly used on those systems.

            For a forced air heating and cooling application with a current Honeywell zone panel (HZ311, HZ322, or HZ432) you would just select the thermostat that would be used for the application if the system was not zoned. In other words, a TH5220D could be used for a 2 stage furnace and AC system whether the system was zoned with an HZ322 or HZ432 zone panel, or if the thermostat directly controlled the equipment in a non-zoned system.

            Some older zone panels used a master and slave thermostat with special wiring. Below are listed common wiring examples for master and slave zones.
            Check the wiring of the thermostat you wish to replace. A master thermostat typically that uses terminals R, W, Y, G, O, and B. The TH4110D1007 is the Honeywell digital-programmable model sold through contractors that can be used as a master. The TH3110D1008 is the Honeywell digital-programmable model that can be used as a master.
            A slave thermostat typically uses 3 wires which are attached to terminals labeled R, W, and Y. The TH6110D and TH8110U thermostats are models sold through HVAC contractors that would work as a replacement for a slave zone.

            You can configure any of these thermostats for auto changeover so that you would not need to change the mode of the slave thermostat every time you switch the mode of the master thermostat.

            Answered on 8/15/2012 by PexSupply Staff from NY
        • Q:

          Does one C7089R1013 wireless outdoor sensor work for multiple Prestige IAQ Thermostats (THX9421R5013 ) ?
          Asked on 6/15/2012 by Dave from RI

          1 answer

          • CUSTOMER CARE


            Yes, each C7089R1013 sensor works with an unlimited number of RedLINK thermostats in its signal range.

            Answered on 6/15/2012 by PexSupply Staff from NY
        Displaying questions 1-2

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