No C Wire Options
Compare no-C-wire smart thermostats by power method: included adapters and extenders, battery power, and the line-voltage systems to rule out.
Honeywell Home RTH21B Programmable Thermostat
Product details
General specs
- Brand: Honeywell Home
- Model: RTH21B
Starting from €44.57
Last price update: 10/4/26
Similar products comparison
| This model | Recommendations | |||||
|---|---|---|---|---|---|---|
Honeywell Home RTH21B White
|
Honeywell Home RTH20B White 5-2 day scheduling
|
Riseem STN701W-Blue Blue
|
Programmable Auto Changeover Thermostat Compatible with single-stage systems
|
Honeywell RENEWRTH9585WF/U Silver Energy Star certified for energy savings
|
SASWELL T18BUTW-7-WIFI(TY) Black
|
|
| Brand | Honeywell Home | Honeywell Home | Riseem | Coiiwsei | Honeywell | SASWELL |
| Model | RTH21B | RTH20B | STN701W-Blue | RENEWRTH9585WF/U | T18BUTW-7-WIFI(TY) | |
| Color |
|
|
|
|
|
|
| Rating |
|
|
|
|
|
|
| Price | €44.57 | €39.19 | €33.45 | €41.91 | €70.43 | €76.69 |
| Seller | Retailer | Retailer | Retailer | Retailer | Retailer | Retailer |
| Update | May 11, 2026 | Jun 24, 2026 | Jun 24, 2026 | May 29, 2026 | May 29, 2026 | Jun 19, 2026 |
| Dimensions | 6.5, 1.6, 8.55 | 8, 6, 0.84 | 0.98, 3.86, 4.72 | 4.5, 3.5, 0.88 | ||
| Scheduling | 7-Day, Weekly | 5-2 Day | 7-Day | Flexible programming | ||
| Connectivity | Wired | Wi-Fi | Wi-Fi | Wi-Fi | ||
| Display Type | LCD | LCD | Extra large backlight LCD | Touchscreen | LED, Color LCD | |
| Power Source | Battery | Battery | Hardwired | Hardwired | Wired | |
| Mounting Type | Wall Mount | Wall Mount | Wall Mount | Wall Mount | Wall-Mounted | |
| Control Methods | Buttons | Buttons | App, Buttons | Touchscreen | App, Voice, Touchscreen | |
| Compatible Systems | Air Conditioner, Gas Boiler, Water Heating | Air Conditioner, Electric Boiler, Gas Boiler, Water Heating | Air Conditioner, Gas Boiler | Forced air (gas, oil or electric), Electric furnace, Hot water steam or gravity radiant heat, Heat only systems, Heat pump w/o auxiliary or emergency heat, Millivolt, Gas fireplaces (24V), Floor or wall furnaces, Cool only systems | Forced air (gas, oil or electric), Hot water and steam, Heat pumps with electric backup | |
When this device makes sense
Product confidence
Reviews
There are no text reviews yet. If you have experience using this product, please leave a review. It will help other people decide whether this product is right for them.