Honeywell CM921 manual To press or buttons

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pRoGRAMMING THE CM921

b.To adjust the period start time press the or buttons and ‘TIME 1 OK?’ will be displayed. Holding the button down will change the time quickly.

Note: If you are pressing the or buttons and the display flashes the next change period, it means the next change will be pushed forward if you continue

to press or buttons).

c.Press the green button to conirm the setting. ‘CHANGES SAVED’ is displayed for 1.5 seconds then ‘SET TEMP 1’ will be shown.

Note: If the original time setting did not require adjustment press the green button to move on to step ‘d.’.

d.The temperature setting for period 1 will now be lashing. To adjust this press the or buttons and ‘TEMP 1 OK?’ will be displayed.

e.Press the green button to conirm the setting. ‘CHANGES SAVED’ will be displayed for a moment followed by ‘SET TIME 2’.

f.The next time and temperature period will now be active. Adjust this by repeating steps b - e above until all 6 periods are set or move the slider switch to the AUTO position to run the program as set, at any time.

g.After setting period 6 ‘CHANGES SAVED’ will be displayed as before.

i.To exit the programming mode move the slider switch to the desired operating mode - AUTO, MAN or OFF. Note: To run the adjusted program select the AUTO mode.

Note: If the unit is left in programming mode for more than 10 minutes without the slider being moved or any buttons pressed, ‘MOVE THE SLIDER’ will be displayed. Press a button to finish programming the thermostat or move the slider to select the desired operating mode.



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Contents CM921 User Guide Plumbnation.co.uk Controls Layout To install the Batteries Installing the BatteriesRunning the Built-in Heating Program Setting the Date and TimeTo set the Date and Time Reviewing the Heating Program Built-in Heating ProgramModifying the Heating Program To press or buttons To enable time periods To disable time periodsDisabling / Enabling Time Periods Adjusting the Time Choosing the Operating ModeDuring Normal Operation To set the Holiday function Using the Special FunctionsTemperature Override Holiday FunctionTo change any of these user’s parameters Changing the User ParametersIii Enable or disable summer/winter time change Ii Reset the built-in program to the factory defaultSymptom Possible Cause Remedy Troubleshooting GuideCheck that there is power to the heating system What is Optimum Start? How do I set one temperature for the whole day?HC60NG Relay Box Controls Layout Wall bracketCan I use my CM921 to control my air-conditioning system? Following explanation applies to heating applications only An explanation for householders42011077-103 R1

CM921 specifications

The Honeywell CM921 is a versatile and highly efficient programmable room thermostat designed to enhance comfort and energy management in residential and light commercial applications. This product exemplifies modern heating control technology, making it an excellent choice for users looking to optimize their heating systems while maintaining user-friendly operation.

One of the key features of the CM921 is its ability to program multiple heating schedules. Users can customize settings for different days of the week, allowing for unique heating profiles that can adapt to varying daily routines. This programming capability helps to reduce energy consumption by ensuring that heating is only active when needed, ultimately lowering energy bills.

The CM921 is equipped with an advanced, easy-to-read digital display that provides clear and concise information about the current room temperature and the set temperature. This intuitive interface simplifies user interaction, enabling quick adjustments when necessary. Additionally, the thermostat features a backlit screen, which facilitates usage even in low-light conditions.

Another notable technology integrated into the Honeywell CM921 is its compatibility with various heating systems. It supports both conventional and combi boiler types, making it a flexible solution for diverse heating requirements. The thermostat can also be connected to a 2-wire system, providing an easy installation process and reducing the need for complex wiring modifications.

Energy-saving features are a significant characteristic of the CM921. The thermostat includes an intelligent frost protection setting, which ensures that the temperature does not fall below a pre-defined level when the home is unoccupied for extended periods. This prevents pipes from freezing and potential damage to the system. Furthermore, the device offers a 'holiday mode', allowing users to save energy during extended absences by automatically adjusting the heating schedule.

In terms of characteristics, the Honeywell CM921 boasts a sleek and modern design, ensuring it fits seamlessly into any home décor. Its compact size makes it suitable for installation in various locations, providing flexibility for homeowners.

Overall, the Honeywell CM921 stands out for its blend of advanced technology, user-friendly features, and energy efficiency. It is an ideal solution for anyone seeking to improve their home’s heating management while enjoying comfort and convenience.
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