Honeywell Home RTH2300/RTH221 Series Programmable Thermostat

The Honeywell Home RTH2300 and RTH221 Series Programmable Thermostats provide reliable and easy-to-use temperature control for your home HVAC system.

Compatible with a variety of heating and cooling systems, these thermostats feature preset energy-saving schedules, manual overrides, compressor protection, and a user-friendly interface.

What Systems Are Compatible?

This thermostat works with these HVAC systems:

• Gas, oil, or electric furnace
• Central air conditioner
• Hot water system (with or without pump)
• Millivolt system
• Central heating and cooling system
• Heat pumps without auxiliary or backup heat

Note:

• Not compatible with heat pumps with backup heat or multi-stage systems.
• Operates on 24 volts or 750 millivolts.

Important Safety Notice

• Do not run air conditioner if outdoor temperature falls below 50°F (10°C) to avoid compressor damage.
• This product does not contain mercury, but may replace a thermostat that does. Dispose of old mercury thermostats properly via local recycling programs.

Installation Instructions

Before You Begin

1. Turn OFF power to your heating/cooling system at the breaker or system switch.
2. Remove the old thermostat but leave wires attached to the wallplate.
3. Label the wires with tags (supplied) to match them correctly with the new thermostat.

Mounting the New Thermostat

1. Remove the new thermostat from its wallplate.
2. Mount the new wallplate on the wall using included screws and anchors.
3. Connect the wires by matching the labels to the thermostat terminals.
4. Insert 2 AAA alkaline batteries into the back of the thermostat.
5. Set the fan operation switch according to your system type:
   • Gas or Oil Furnace: Leave as factory-set for fan control on heat call.
   • Electric or Heat Pump: Move switch to this setting if fan control is needed and a fan wire is connected to the G terminal.
6. Attach the thermostat body onto the wallplate.
7. Turn power back ON to your HVAC system.

Advanced Installation Setup

If your system is a heat pump, high-efficiency furnace, hot water system, electric furnace, steam, or gravity heating system, enter advanced setup mode:

• Press and hold both the up (▲) and down (▼) buttons for ~5 seconds until display changes.
• Use buttons to select your system type, set Fahrenheit or Celsius, enable compressor protection, set clock display format, and filter change reminders (RTH2300 only).

Thermostat Controls and Display

Main Controls

• System Switch: Select Heat, Off, or Cool.
• Fan Switch: Set to Auto (fan runs only with system) or On (fan runs continuously).
• Up (▲)/Down (▼): Adjust temperature setpoint.
• Set: Program time, day, and schedules.
• Hold: Permanently override schedule temperature.
• Run: Resume programmed schedule.

Display Elements

• Shows current ambient temperature by default.
• Setpoint temperature appears briefly when buttons pressed.
• System status indicators: “Heat On”, “Cool On” messages.
• Time and day of week display (RTH2300 includes day).
• Low battery warning (“Lo Batt”).
• Program period indicator (Wake/Leave/Return/Sleep).

Programming Your Thermostat

Setting the Clock and Day

1. Press Set, use ▲/▼ to set the time.
2. Press Set again to set the day of the week (RTH2300 only).
3. Press Run to save.

Understanding Program Periods

You can set up to four daily time periods to optimize comfort and save energy:

• Wake: When you get up.
• Leave: When you leave home, energy-saving temperatures apply.
• Return: When you come back home.
• Sleep: Nighttime sleeping period.

Default Preset Schedules (recommended)

Adjusting Program Schedules

• Press Set until “Set Schedule” appears.
• Use ▲/▼ to set times and temperatures for each period for weekdays (Mo-Fr).
• Press Set to switch to weekends to set weekend schedules separately (RTH2300 only).
• Press Run to save and exit.

Temporary Override

• Press ▲/▼ to change temperature temporarily for current period.
• “Temporary” will show on display; returns to schedule at next period.
• Press Run anytime to cancel temporary override.

Permanent Override (Hold)

• Press Hold to maintain a temperature all day, overriding schedule.
• Press Run to cancel Hold mode and resume schedule.

Additional Features

Compressor Protection

• Prevents compressor damage by delaying restart for about 5 minutes after shutdown.
• During this time, display flashes “Cool On” or “Heat On”.

Change Filter Reminder (RTH2300 only)

• If enabled at setup, “Change Filter” flashes when it’s time to replace your HVAC filter.
• After replacement, press and hold Run for 3 seconds to reset the reminder.

Battery Replacement

• Use two AAA alkaline batteries.
• Replace when “Lo Batt” flashes (appears ~60 days before depletion) or annually.
• Before removing batteries, switch System to Off to avoid HVAC running unintentionally.
• After battery replacement, only time and day may need resetting.

Troubleshooting

For further assistance, visit Honeywell Home Support.

Warranty

This product includes a 1-year limited warranty. For full terms and customer support, visit the official Honeywell Home website.

Summary

Your Honeywell Home RTH2300/RTH221 thermostat is designed for easy installation, convenient scheduling, and energy savings with built-in compressor protection and flexible overrides.

Programming and operation are straightforward with clear button controls and display feedback—ensuring comfortable, efficient heating and cooling year-round.

For detailed wiring diagrams, advanced settings, and complete instructions, please refer to the full Honeywell Home RTH2300/RTH221 Owner’s Manual.