6 min read • Updated October 2026 • By the CliQ Team — the team that created Blink
How do you set a Honeywell thermostat? Choose Heat or Cool, using the Mode button or the System switch, then press the up or down button to the temperature you want. That temperature holds until the next scheduled period starts. To keep it, press Hold. To set a weekly schedule, open the schedule menu (Menu, then PROG, on a T4 Pro, or press Set until "Set Schedule" appears on an RTH model) and enter a time and temperature for each of the four daily periods.
The buttons differ by model, so start by working out which Honeywell you have. This covers two widely used programmable families, the T4 Pro and the RTH2300/RTH221. Their manuals and Honeywell's own videos are the sources.
Which Honeywell Do You Have?
You can tell from the buttons. For the exact model, Honeywell says the number is on a sticker on the back of the thermostat.
| T4 Pro (TH4110U, TH4210U) | RTH2300 / RTH221 | |
|---|---|---|
| How to spot it | Five buttons under the screen: Mode, Fan, Menu, and – / + | Set, Hold, and Run buttons, plus sliding System and Fan switches |
| Heat or cool | Press Mode | Slide the System switch |
| Change the temperature | Press – or + | Press the up or down button |
| Hold a temperature | Press Hold while the setpoint flashes | Press Hold |
| Back to the schedule | Press – or +, then Cancel | Press Run |
| Edit the schedule | Menu, then PROG | Press Set until "Set Schedule" appears |
| Daily periods | Wake, Away, Home, Sleep | Wake, Leave, Return, Sleep |
How to Set the Temperature
- Pick the mode. On a T4 Pro, press Mode until Heat or Cool shows, then leave it. Depending on your system, you may also see Auto, Off, or Em Heat. On an RTH, slide the System switch to Heat or Cool.
- Press up or down (– or + on the T4 Pro) until you reach the temperature you want. On an RTH, the screen normally shows the room temperature. Press up or down once to see the setpoint for five seconds.
- Leave the fan on Auto. Auto runs the blower only while the system heats or cools. On runs it all the time, and the T4 Pro's fan has no timer, so it stays on until you switch it back.
Video by Roy's Plumbing, Heating & Cooling via YouTube, August 2018. Not affiliated with CliQ.
In about two minutes, a technician tours the whole T4 Pro. The setpoint is at the top of the screen and the room temperature is in the middle. He walks through the Fan, Mode, and +/– buttons, then shows the difference between a hold and a temporary change.
Hold vs. Schedule: Make a Change Stick (or Not)
Both families give you two ways to override the schedule.
- Temporary: just press up or down. The new temperature lasts until the next scheduled period, then the schedule takes over again. Use it for "a little warmer tonight."
- Permanent (Hold): the temperature stays put, around the clock, until you change it or cancel the hold. On an RTH, press Hold. On a T4 Pro, change the temperature, and while "Temporary Hold" shows and the setpoint flashes, press the Hold button (the Mode button). Use it for vacations, or if you'd rather not run a schedule at all.
To go back to the schedule: on an RTH, press Run. On a T4 Pro, press – or +, then Cancel.
The thermostat "ignores" its schedule? Check for a forgotten permanent Hold first. Look for "Hold" on the screen and cancel it. If that's not it, see why a programmable thermostat stops following its schedule.
How to Set the Schedule
Both families split each day into four periods: when you wake up, leave, come home, and go to bed. Each period gets a start time and a temperature.
T4 Pro
- Press Menu. PROG appears. Press Select, make sure it says ON, and press Select again.
- Use – or + to choose the day or group of days to edit. Press Select.
- Choose a period (Wake, Away, Home, or Sleep). Press Select, then Select again to keep the period on.
- The time blinks. Adjust it and press Select.
- Set the Heat temperature and press Select. Then set the Cool temperature and press Select.
- Repeat for the other periods. Press Home to save.
RTH2300 and RTH221
- Slide the System switch to Heat or Cool. Honeywell's manual says to set it to the system you want to program before you start.
- Press Set until "Set Schedule" appears.
- Use the arrows to set the Wake time and press Set. Then set the Wake temperature and press Set.
- Repeat for Leave, Return, and Sleep.
- On the RTH2300, which has separate weekday and weekend schedules, press Set to move on to Saturday and Sunday and repeat. The RTH221 uses one schedule for all seven days.
- Press Run to save and exit.
Video by Honeywell Home via YouTube, December 2018. Not affiliated with CliQ.
Honeywell's own two-minute walkthrough of the RTH2300. Set the day and time first, then step through the four weekday settings and the four weekend settings with the arrows and Set. When you finish, it drops you back on the main screen.
What temperatures to use
Both manuals suggest the same starting points and recommend them because they can reduce heating and cooling costs:
| Period | Default time | Heat | Cool |
|---|---|---|---|
| Wake | 6:00 am | 70°F | 78°F |
| Away / Leave | 8:00 am | 62°F | 85°F |
| Home / Return | 6:00 pm | 70°F | 78°F |
| Sleep | 10:00 pm | 62°F | 82°F |
Set the times to your real routine. The setbacks are where the savings come from: the US Department of Energy says setting the thermostat back 7–10°F for 8 hours a day can save up to 10% a year on heating and cooling. DOE also notes that setbacks aren't recommended for heat pumps, so go easier on them if that's your system. For more on picking temperatures, see our guide to programming any thermostat.
Set the Time, Date, and Keypad Lock
Set the time and day
T4 Pro: press Menu, go to TIME, and press Select. Choose 12- or 24-hour, then set the hour and minutes, pressing Select after each. DATE in the same menu sets the year, month, and day. RTH: press Set and use the arrows for the time. Press Set again for the day of the week, then press Run to save. If the RTH clock is flashing, the thermostat follows Monday's Wake setting until you set the time.
Unlock a T4 Pro keypad
Press the center button and enter the password 1234. Use – or + to set each digit, press Select after each one, then press Select once more. To change the lock, go to Menu, then LOCK: OFF is fully unlocked, PART allows temperature changes only, and ON locks everything. On some models, the lock setting is only in the installer menu.
Buttons do nothing on an RTH
Check the System switch. Honeywell's manual says it must be set to the system you want to control, Heat or Cool. Off turns everything off. Then check the batteries: RTH models show "Lo Batt" when they're low.
Thinking about replacing your thermostat instead?
See the CliQ Smart Thermostat →Frequently Asked Questions
How do I set the temperature on a Honeywell thermostat?
Pick Heat or Cool (the Mode button on a T4 Pro, or the System switch on an RTH), then press up or down to the temperature you want. It holds until the next scheduled period. Press Hold to keep it longer.
How do I make my Honeywell thermostat stay at one temperature?
Use a permanent hold. On an RTH, press Hold. On a T4 Pro, change the temperature, then press Hold while the setpoint is flashing. The temperature stays until you change it or cancel the hold: Run on an RTH, or – / + then Cancel on a T4 Pro.
How do I reprogram my Honeywell thermostat schedule?
On a T4 Pro, press Menu, then PROG, choose the days and period, and set the time and temperatures. Press Home to save. On an RTH2300 or RTH221, press Set until "Set Schedule" appears, set each period's time and temperature, and press Run to save.
How do I unlock a Honeywell T4 Pro thermostat?
Press the center button and enter the password 1234, setting each digit with – or + and pressing Select after each. Press Select again to unlock. On some models, the lock setting is only in the installer menu.
Why does my Honeywell thermostat go back to the old temperature?
It's following the schedule. Pressing up or down only changes the temperature until the next scheduled period starts. To keep a temperature, use Hold, or change that period in the schedule.
Where do I find my Honeywell thermostat's model number?
On a sticker on the back of the thermostat, according to Honeywell. Gently pull the thermostat off its wall plate to see it. Then search "Honeywell [model number] manual" for model-specific steps.
Sources
Resideo — T4 Pro Programmable Thermostat TH4110U2005, TH4210U2002 User Guide (33-00188EFS-11, 2022) — PDF
Resideo — Programmable RTH2300/RTH221 Thermostat Series Owner's Manual — PDF
Honeywell Home — Programming Schedules on the Honeywell Home RTH2300 Thermostat (video) — youtube.com
US Department of Energy — Programmable Thermostats — energy.gov
Photo by Vitaly Gariev via Pexels
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