Honeywell YTHX9421R5101SG/U

Honeywell YTHX9421R5101SG/U 2-Wire Touchscreen Programmable Thermostat, 40 - 90 deg F Heat, 50 - 99 deg F Cool, Black


Manufacturer part number:




Honeywell Prestige® YTHX9421R Programmable Thermostat, 2-Wire, Touchscreen, 40 - 90 deg F Heat, 50 - 99 deg F Cool, +/-1 deg F Differential, 4 Heat Pump, 3 Conventional Stages Heat, 2 Heat Pump, 2 Conventional Stages Cool, Programs Per Week: 7, 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, System Switching: Heat-Off-Cool-Auto-Emergency-Heat, Fan Switching: Auto-On-Circulate-Follow Schedule, 8.06 sq-Inch Display, 18/30 VAC, 50/60 Hz, Hardwired, Black, 3-1/2 Inch L x 4-1/2 Inch W x 7/8 Inch D, Includes: THM5421R1021 Equipment Interface Module, C7089R1013 Wireless Outdoor Sensor and (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
  • Smart schedule - programs in seconds for any lifestyle
  • Patented interview based programming and installer setup
  • RedLINK™ wireless communication
  • 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, wireless entry/exit remote, wireless vent and filter boost remote, TrueSTEAM™ humidifier with wireless adapter and TrueZONE® zoning panel with wireless adapter
  • 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 performing as expected with instructions to contact the dealer. Provides a sense of security and greater comfort while generating repeat business
  • All Prestige® IAQ kits 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 user error. Saves time in troubleshooting and points the technician in the right direction
  • Performance logs - keeps a history of heating and cooling performance. The performance log includes minimum and maximum Delta T, minimum and maximum discharge temperature, minimum and maximum return temperature, minimum and maximum indoor temperature/humidity, minimum and maximum outdoor temperature/humidity and run time. Quickly determine if the system is performing as expected and reduces service time on the job
  • 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 setup customizable reminders, custom events and holidays to multiple thermostats
  • USB port for adding the dealer's full color business logo on the screen
  • 3 assignable outputs to control humidification, dehumidification, ventilation and a stage of heating or cooling
  • 4 assignable inputs on the equipment interface module can be used with wired outdoor, indoor or discharge sensors, occupancy sensor for remote setback and dry contact devices to trip pre-packaged or custom alerts such as a full drain pan or water leak
  • Extend wireless range of the equipment interface module by connecting a THM4000R1000 wireless adapter to the ABCD terminals
  • Precise temperature control (+/- 1 deg F) for reliable and consistent temperature
  • Multiple staging options to provide comfort or energy savings

Application: Residential and Light Commercial

Products specifications
Attribute nameAttribute value
ApplicationConventional or Heat Pump
Brand NameHoneywell
Control Range40 - 90 deg F Heat, 50 - 99 deg F Cool
Differential+/-1 deg F
Dimensions3-1/2 Inch L x 4-1/2 Inch W x 7/8 Inch D
Display8.06 sq-Inch
Fan SwitchingAuto-On-Circulate-Follow Schedule
Number of Stages3H/2C Conventional, 4H/2C Heat Pump
Power SourceHardwired
Programs Per Week7
SeriesPrestige®, YTHX9421R
Stages Cool2 Heat Pump, 2 Conventional
Stages Heat4 Heat Pump, 3 Conventional
System SwitchingHeat-Off-Cool Auto Emergency Heat
Type2-Wire, Touchscreen
Voltage Rating18/30 VAC, 50/60 Hz