Honeywell RTH221B Thermostat Instruction Manual

Name: Honeywell RTH221B Thermostat Instruction Manual
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Honeywell RTH221B Thermostat Instruction Manual

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📖 Manual 📋 Specifications 📝 Summary 💬 FAQs

Honeywell RTH221B Thermostat

User Manual

24 pages

Installation Guide

26 pages

Honeywell RTH221B Instructions

Here we offer the Honeywell RTH221B Thermostat manual completely free and in English. We have cataloged this manual in the Thermostats section on Manualverse, and it has been rated by 1 users with an average rating of 5. If you have any specific questions about Honeywell RTH221B Thermostat, we suggest checking the Frequently Asked Questions (FAQs) section of this manual.

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Honeywell RTH221B Thermostat Specifications

Feature	Specification
Model	Honeywell RTH221B Programmable Thermostat
Compatibility	Conventional systems (Gas, oil, electric furnace, central A/C, hot water system with/without pump, millivolt system, central heating/cooling). Heat pump without auxiliary/backup heat.
Incompatibility	Heat pumps with auxiliary/backup heat, multi-stage conventional systems, 120/240 Volt systems.
Power Supply	2 AAA alkaline batteries (24 volt or 750 mV systems)
Heating Temperature Range	40°F to 90°F (4.5°C to 32°C)
Cooling Temperature Range	50°F to 99°F (10°C to 37°C)
Programming	4 time periods per day (Wake, Leave, Return, Sleep), same schedule for all 7 days (Mo-Su).
Compressor Protection	Built-in 5-minute delay before restart.
Display	Standard LCD (non-backlit). Displays ambient and setpoint temperature.
Battery Warning	"Lo Batt" indicator flashes 60 days prior to battery depletion.
Warranty	1-year limited warranty.

Honeywell RTH221B Thermostat Details

The Honeywell RTH221B thermostat offers a user-friendly experience with its straightforward push-button climate control, designed for reliability and ease of use. This model prioritizes energy savings, coming pre-programmed with settings that can significantly reduce heating and cooling expenses. Users need only set the current time and day to get started, as the default schedule is ready for immediate operation.

A key feature is its ability to constantly display the ambient (measured) room temperature, with one-touch access to view the setpoint temperature. The intuitive controls include dedicated system (Heat, Off, Cool) and fan (Auto, On) switches, allowing easy adjustment of your HVAC system's mode and fan operation. The "Auto" fan setting is the most common, ensuring the fan only runs when heating or cooling is active.

The RTH221B offers a 7-day programmable schedule, which means the same four daily time periods—Wake, Leave, Return, and Sleep—apply consistently across all days of the week. Each period can be customized with its own temperature setting, enabling users to create an energy-efficient climate plan tailored to their daily routine. This simple, unified schedule makes programming less complex compared to multi-day differentiated systems.

For moments when your routine deviates, the thermostat provides flexible override options. A *temporary override* allows you to adjust the temperature, which holds until the next programmed time period begins. For longer changes, the permanent override activates a "Hold" feature, maintaining a set temperature 24 hours a day until manually canceled or reset, effectively turning off the program schedule.

Additional functionalities include a built-in compressor protection feature, which safeguards your air conditioning or heat pump by enforcing a 5-minute delay before restarting. This prevents potential equipment damage. The thermostat also offers customizable advanced settings, such as selecting the heating cycle rate to optimize performance for different furnace types (gas, electric, hot water, steam), choosing between Fahrenheit or Celsius temperature display, and setting a 12-hour or 24-hour clock display.

Battery replacement is simple, with a "Lo Batt" warning providing ample notice. Most settings are saved in non-volatile memory, so only the clock and day require resetting after new AAA batteries are installed. This robust set of features makes the RTH221B a practical choice for managing home comfort efficiently.

Frequently Asked Questions (FAQs)

Can't find the answer you need? Here are some frequently asked questions about the Honeywell RTH221B Thermostat, and we answer them below.

How do I set the time and day on my Honeywell RTH221B thermostat?

Press the SET button, then use the up or down arrows to adjust the clock time. Press SET again, then use the arrows to select the day of the week. Finally, press RUN to save and exit.

What do the SYSTEM switch settings (Heat, Off, Cool) do?

The SYSTEM switch controls your HVAC system. 'Heat' activates the heating system, 'Cool' activates the cooling system, and 'Off' turns all systems off.

What do the FAN switch settings (Auto, On) do?

In 'Auto' mode, the fan runs only when the heating or cooling system is actively running. In 'On' mode, the fan runs continuously, regardless of whether heating or cooling is active.

My thermostat display is blank. What should I do?

First, ensure your furnace door is securely closed. Then, check if fresh AAA alkaline batteries are correctly installed. If the issue persists, check your circuit breaker.

Why isn't my heating or cooling system responding?

Make sure the SYSTEM switch is set to the correct mode (Heat or Cool) and the set temperature is appropriately higher (for heat) or lower (for cool) than the ambient temperature. Also, allow 5 minutes for the system to respond due to built-in protection, and ensure the heating/cooling power switches are on.

Why are the words 'Cool On' or 'Heat On' flashing on the display?

This indicates that the compressor protection feature is engaged. Your system is waiting approximately 5 minutes before restarting safely to prevent damage to the compressor. The message will stop flashing once the safe wait time has elapsed.

How do I temporarily override the program schedule?

Simply press the up or down arrow buttons to adjust the temperature. The new temperature will be maintained until the next programmed time period begins. 'Temporary' will appear on the display.

How do I permanently override the program schedule?

Press the HOLD button, then use the up or down arrows to set your desired temperature. This will maintain the set temperature 24 hours a day, overriding all programmed settings, until you press RUN to cancel 'Hold' and resume the schedule.

What does the 'Lo Batt' message mean, and when should I replace the batteries?

'Lo Batt' indicates that the batteries are low. It will flash for 60 days before the batteries are depleted. You should install two fresh AAA alkaline batteries when this message appears, or at least once a year. Remember to set the SYSTEM switch to Off before removing batteries.

Is the Honeywell RTH221B compatible with all HVAC systems?

It is compatible with most conventional 24 volt or 750 mV systems, including single-stage heat and cool, heat only, cool only, and heat pumps without auxiliary/backup heat. It is NOT compatible with heat pumps with auxiliary/backup heat, multi-stage conventional systems, or 120/240 Volt systems.

Can I change the temperature display from Fahrenheit to Celsius?

Yes, you can change the temperature display in the Advanced Installation setup. Access system setup by pressing and holding both the up and down arrow buttons for about 5 seconds. Navigate to Function 14 and select '0' for Fahrenheit or '1' for Celsius.

Does the RTH221B have a filter change reminder?

No, the RTH221B model does not include a filter change reminder feature. This functionality is available on the RTH2300 model.

What happens if the clock flashes after a power interruption or battery change?

If the clock flashes, the thermostat will follow your settings for the Monday 'Wake' time period until you reset the time and day. Most other settings are stored in non-volatile memory and will not be lost.