| Supply Voltage | 18 to 30 Vac |
| Frequency | 50 Hz; 60 Hz |
| Electrical Connections | Screw terminals |
| Electrical Ratings | 18 to 30 Vac |
| Operating Temperature | 32 F to 120 F |
| Operating Humidity | 5 to 90% RH, non-condensing |
| Application | Up to 3 Heat/2 Cool Conventional Systems; Up to 4 Heat/2 Cool Heat Pumps |
| Used With | THM5421R1021 Equipment Interface Module and RedLINK™ accessories |
| Dimensions | 3 1/2 in. High, 4 1/2 in. Wide, 7/8 in. Deep |
| Hazmat Information | Lithium metal button cells only contained in equipment, Excepted per PI970 |
| Stages | Up to 4 Heat/2 Cool Heat Pumps; Up to 3 Heat/2 Cool Conventional Systems, See Equipment Interface Module |
| Switch Positions (System) | HEAT-OFF-COOL-AUTO-EM.HEAT |
| Switch Positions (Fan) | AUTO-ON-CIRC-FOLLOW SCHEDULE |
| Power Method | Hardwired |
| Color | Front: White, Side: White |
| Programmability | 7 Day Program or Non-Programmable |
| Terminal Designations | R, C then RedLINK to Equipment Interface Module |
| Display Size | 8.06 sq in. |
| Changeover | Auto or Manual |
| Setting Temperature Range (F) | Heat: 40 F to 90 F; Cool 50 F to 99F |
| Humidification Setting Range | Cooling: 40 to 80% RH. Heating: 10 to 60% RH. |
| Dehumidification Setting Range | 40 to 80% RH. |
Description
The THX9421R5021WW is a Prestige thermostat from Resideo (Honeywell Home), Up to 4 Heat/2 Cool Heat Pumps; Up to 3 Heat/2 Cool Conventional Systems, See Equipment Interface Module.
A thermostat earns its price on the equipment it can drive properly, not on the screen. Multi-stage heating, a heat pump with auxiliary, humidification and ventilation are all decisions the thermostat makes or fails to make; a stat that can only switch one stage runs two-stage equipment as though it were single-stage and throws away the efficiency that was paid for.
This one drives Up to 4 Heat/2 Cool Heat Pumps; Up to 3 Heat/2 Cool Conventional Systems, See Equipment Interface Module. Check that against the equipment before ordering — it is the specification that decides whether the install works, and the one most often skipped in favor of the feature list.
RedLINK is what lets it work with wireless sensors, outdoor sensors and equipment modules without pulling wire for each one. On a retrofit that is the difference between a thermostat swap and opening walls.
Used with: THM5421R1021 Equipment Interface Module and RedLINK™ accessories.
Goes with: THM5421R1021.
- Brand: Resideo (Honeywell Home)
- Manufacturer Part #: THX9421R5021WW/U
- Type: Prestige thermostat
- Stages: Up to 4 Heat/2 Cool Heat Pumps; Up to 3 Heat/2 Cool Conventional Systems, See Equipment Interface Module
- Supply voltage: 18 to 30 Vac
- System switch: HEAT-OFF-COOL-AUTO-EM.HEAT
- Application: Up to 3 Heat/2 Cool Conventional Systems; Up to 4 Heat/2 Cool Heat Pumps
- Used with: THM5421R1021 Equipment Interface Module and RedLINK™ accessories
- Dimensions: 3 1/2 in High, 4 1/2 in Wide, 7/8 in Deep
- UPC: 085267653626
- Category: Thermostats