Hercules Product Info 
Hercules Product IdYTHX9421R5127WW
Product DescriptionSYSTEM TOUCHSCREEN COMFORT IAQ 6 WHT 2-W
Unit of MeasureEA
Manufacturer Info 
Manufacturer NameHoneywell
Brand NameHoneywell
Part NumberYTHX9421R5127WW/U
Product UPC085267136945
Product DescriptionHoneywell Prestige YTHX9421R5127WW/U 2-Wire IAQ Comfort Touchscreen System, Programmable Thermostat, 40 to 90 deg F Control
Product Features
The Prestige IAQ thermostat is a 2 wire high definition color touch screen thermostat, 7 day programmable and selectable for residential or light commercial use. Controls up to 4-stages of heat and 2-stages of cool in a heat pump system and up to 3-stages of heat and 2-stages of cool in a conventional system. Three sets of Universal IAQ contacts to control humidification, dehumidification and ventilation. Four sensor inputs for wired sensors or dry contact devices. Works with the Equipment Interface Module and RedLINK accessories including the RedLINK Internet Gateway, Portable Comfort Control, Wireless Outdoor Sensor and Wireless Indoor Sensor.
Applications: Residential and Light Commercial
Includes: THX9421R5021WW Prestige 2-Wire IAQ Thermostat, THM5421R1021 Equipment Interface Module, THM6000R1002 RedLINK Internet Gatewayand (2) Duct Sensors
Control heating, cooling and IAQ equipment with only 2 wires at the thermostat, heating, cooling and IAQ equipment wires to the equipment interface module
Patented interview based programming and installer setup
RedLINK wireless communications
Increase profit per job by including RedLINK accessories that provide comfort and convenience, RedLINK accessories include the RedLINK internet Gateway, portable comfort control (PCC), wireless outdoor sensor wireless indoor sensor TrueSTEAM humidifier with wireless adapter and TrueZONE zoning panel with wireless adapter
Configurable for residential and light commercial applications, meets commercial code and is title 24 compliant
Light commercial - commercial language (occupied and unoccupied), schedule holidays and custom events, remote setback, economizer and time of day
Delta T alerts and diagnostics informs customers when their system is not operating as expected with instructions to contact the dealers
Provides a sense of security and greater comfort while generating repeat business
All Prestige IAQ 2.0 systems come standard with a return and discharge air temperature sensor to measure Delta T
Alerts and user interactions log - Keeps a searchable history of alerts and setting changes to the thermostat to determine if there is a system malfunction or if the issue was caused by a user error, saves time in troubleshooting and points the technician in the right direction, the alerts and user interaction Logs are viewable on a computer after you download them from the thermostat to a MicroSD card
Customizable service reminders allow dealers to remind their customers when its time to call for service, when their warranty is expiring and to provide customized alerts
USB port for transferring installer set up customizable reminders, custom events and holidays to multiple thermostats
USB port for adding the dealers full color business logo on the screen
3 assignable outputs on the equipment interface module to control humidification, dehumidification, ventilation or a stage of heating or cooling
2 assignable inputs can be used with wired sensors, remote setback or dry contact devices to trip pre-packaged or custom alerts such as a full drain pan or water leak
Precise temperature control (+/-1 deg F) for reliable and consistent temperature
Multiple staging options to provide comfort or energy savings
Product Documents 
Document TypeDownload Link
Owners/User ManualYTHX9421R5127WW_Owners/User Manual (pdf)
Specification SheetYTHX9421R5127WW_Specification Sheet (pdf)
Product Specifications 
Color White
Control Range 40 to 90 deg F
Dimensions 4-1/2 in W x 7/8 in D x 3-1/2 in H deg F
Display Type 8.06 sq-in Tri-Lingual
Fan Switching Auto/On/Circulate/Follow Schedule
Humidity Range 5 to 90% Non-Condensing
Number of Stages 6
Power Source Hardwired
Stages Cool 2 Heat Pump, 2 Conventional
Stages Heat 4 Heat Pump, 3 Conventional
System Switching Heat/Cool/Auto/Off
Terminal Designations R, RC, RH, C, W-O/B, W2-AUX1, W3-AUX2, Y, Y2, G, A-L/A, U1, U1, U2, U2, U3, U3, S1, S1, S2, S2, S3, S3, S4, S4, A, B, C, D
Thermostat Type Programmable
Type 2-Wire
Voltage Rating 18 to 30 VAC