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Honeywell Home RTH21B Programmable Thermostat: Flexible scheduling with 7-day, 5-1-1 day, 5-2 day, or 1 week options
This Honeywell Home thermostat is for the homeowner who wants to save on energy bills without constant manual adjustments. It replaces the hassle of daily temperature tweaks with a tool for effortless comfort control.
Set a flexible schedule that fits your life, like programming lower heat while you're at work and warming up the house before you return. The large, backlit screen makes it easy to check settings from across the room. You'll appreciate the change filter reminder, which helps maintain your HVAC system's efficiency before issues arise.
Compatible with most single-stage heating and cooling systems, this thermostat installs simply with the included wall plate. Use it to create a personalized routine that keeps your home comfortable and reduces energy waste.
Features
- 1 Heat/1 Cool compatibility for forced air systems
- Large backlit display with clear font
- Change air filter reminder and custom display settings
- Easy installation with UWP wall plate
- Extended 32°F low-heat setpoint
- Flexible scheduling with 7-day, 5-1-1 day, 5-2 day, or 1 week options
General specs
- Brand: Honeywell Home
- Model: RTH21B
- Seller: Amazon
- ID: B0DSGF9GDJ
- Material: Plastic
- Dimensions: 6.5, 1.6, 8.55
- Scheduling: 7-Day, Weekly
- Connectivity: Wired
- Display Type: LCD
- Power Source: Battery
- Mounting Type: Wall Mount
- Control Methods: Buttons
- Compatible Systems: Air Conditioner, Gas Boiler, Water Heating
- First listed by seller: January 14, 2026
If you are interested in more details, you can find full information on the seller's page.
Amazon live offers
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Top live offer is the offer currently shown first for this Amazon listing. It may differ from the lowest available price.
FBA means the order is fulfilled by Amazon, even when the seller is a third-party merchant.
Shippable means the offer is listed as available for delivery on Amazon.
New, Used and Refurbished describe the item condition shown for that Amazon offer.
Top live offer
€43.04
Free shipping
New
Third-party seller
FBA
Shippable
New from
€43.00
Only from New + Shippable live offers
Used from
€19.43
Only from Used + Shippable live offers
New offers
Third-party seller
· FBA · Shippable
€43.04
Third-party seller
· Shippable
€43.00
Third-party seller
· FBA · Shippable
€43.05
Third-party seller
· Shippable
€45.65
Third-party seller
· Shippable
€47.34
Third-party seller
· Shippable
€48.17
Third-party seller
· Shippable
€49.19
Third-party seller
· Shippable
€49.66
Third-party seller
· Shippable
€52.60
Third-party seller
· Shippable
€58.35
Third-party seller
· Shippable
€59.62
Third-party seller
· FBA · Shippable
€60.26
Third-party seller
· Shippable
€69.47
Third-party seller
· Shippable
€75.98
Used offers
Used - Very Good
· Third-party seller
· FBA · Shippable
€19.43
Used - Very Good
· Third-party seller
· Shippable
€19.63
Used - Like New
· Third-party seller
· Shippable
€21.52
Used - Like New
· Third-party seller
· FBA · Shippable
€21.70
Used - Like New
· Third-party seller
· FBA · Shippable
€28.40
Used - Like New
· Third-party seller
· FBA · Shippable
€20.33
Used - Very Good
· Third-party seller
· FBA · Shippable
€27.85
Offers updated: 9/1/26
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Price History for seller Amazon
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| Brand | Honeywell Home | Honeywell Home | Riseem | Coiiwsei | Honeywell | SASWELL |
| Model | RTH21B | RTH20B | STN701W-Blue | RENEWRTH9585WF/U | T18BUTW-7-WIFI(TY) | |
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| Price | €43.04 | €32.41 | €34.43 | €40.46 | €77.48 | €55.95 |
| Seller | Amazon | Amazon | Amazon | Amazon | Amazon | Amazon |
| 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 | |
Honeywell Home RTH21B White
€43.04
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