Will it work with your system?
Works well with
- A weekly schedule without an app
- Older wiring without a C wire
Check first if you have
- Phone or voice control
- Line-voltage baseboard heat
What it controls
The Honeywell Home RTH221B1039 Programmable Thermostat is a programmable. Systems, per the maker: COMPATIBLE WITH: Heating, cooling and heat pumps without auxiliary heat options.
Power is where installs stall: the listing doesn't say whether it needs a C wire. C-wire options.
The maker states heat pump support ("Heating, cooling and heat pumps without auxiliary heat options"), so it can drive an O/B reversing valve. What a heat pump needs from a thermostat.
Stages, per the maker: multi-stage. A second-stage wire (W2 or Y2) at your old thermostat needs matching support here. Single- and two-stage systems.
Schedule: Programmable. Program sleep and away setbacks once and it runs them every week.
Power, per the listing: Battery Powered. Battery models often fit old two-wire circuits with no C wire.
Not sure of your wiring? The wiring checker reads your system from the terminal letters and checks it against this model's statements.
Also on the listing: dimensions of 1 in (D) x 4.75 in (W) x 3.5 in (H), a weight of 4.8 ounces and a digital.
Warranty, per the listing: 1 year limited.
Compatibility and specs
These come from the maker's listing for this exact model; the source of each is marked. Anything the maker leaves out is marked not stated.
| Model number | RTH221B1039 | Retailer |
|---|---|---|
| Model name | RTH221B | Retailer |
| Dimensions (seller) | 1"D x 4.75"W x 3.5"H | Retailer |
| Works with | Hand Control | Retailer |
| Features (seller) | Clock Display, Low Battery Indicator, Low Voltage, Programmable | Retailer |
| Connectivity | Non-connected | Retailer |
| Power | Battery Powered | Retailer |
| Voltage | 24 V | Retailer |
| Display | Digital | Retailer |
| Mounting / installation | Wall Mount | Retailer |
| Batteries | 2 AA batteries required. | Retailer |
| Material | Plastic | Retailer |
| Warranty | 1 year limited. | Retailer |
| Product weight | 4.8 ounces | Retailer |
| Works with systems | COMPATIBLE WITH: Heating, cooling and heat pumps without auxiliary heat options | Retailer |
| Heat / cool stages | multi-stage | Retailer |
| Heat pump support | Heating, cooling and heat pumps without auxiliary heat options | Retailer |
| Schedule | Programmable | Retailer |
Strong points and weak points
Strong points
- Programmable
- Power: Battery Powered
- No Wi-Fi or account needed
- Heat pump support stated
Weak points
- No remote control
- Batteries to replace
Wiring and install notes
- Compatibility statements are the maker's own. Confirm with the maker's compatibility checker, turn the power off before wiring, and leave line-voltage and furnace work to a licensed electrician or HVAC technician.
Thermostats to compare it with
FAQ
Does the Honeywell Home RTH221B1039 Programmable Thermostat need a C wire?
What systems does the Honeywell Home RTH221B1039 Programmable Thermostat work with?
Other programmable and basic thermostats with similar wiring
- Honeywell Home RTH7560E1001/N Programmable Thermostat
- Honeywell Home RTH8560D1002 Programmable Thermostat
- Honeywell Home TH6210U2001 Programmable Thermostat
- Honeywell Home RTH7500D Programmable Thermostat
All programmable and basic thermostats in one grid · Every Honeywell Home control listed
Our take
A fit for A weekly schedule without an app.
Where to get it
The link goes to this exact model's listing. Check that the box includes the trim plate or C-wire adapter you need, and confirm your wiring with the maker's compatibility checker before you order.
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