17 February, 2026
Top 5 Best Cm921 Replacement of 2026
Last Updated - 17 February, 2026
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Up to 31% off
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Our Rankings
TotalHome
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TotalHome - Wireless Room Thermostat & Receiver (Honeywell/Resideo) CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk2 Replacement) (TTHWFP)
28% Off
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Why We Love It
- TotalHome is designed and manufactured by Honeywell/Resideo.
- Direct replacement for the Honeywell models CM927, CMS927, CM727, and CM921
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Our Rankings
Hanicks
Honeywell-Resideo Totalhome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk 3 Replacement) Wireless Room Thermostat & Receiver TTHWFP - Hanicks
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Main Highlights
- The Pro Series Wireless Programmable Thermostat is a BRAND NEW 2021 launched, 7 day programmable room thermostat designed to replace all existing Honeywell CM Series Wireless Thermostats. The 'Pro Series' is made in the UK by Resideo (who were formally part of Honeywell International Inc.) and distributed by Hanicks Ltd.
- The Pro Series Wireless Programmable Thermostat will replace the following Honeywell CM Series products: CM921, CMS921, CMS921B1042 CM927, CMS927, CMS927B1049 CM727, CMS727, CMS727E1016 CM721, CMS721
- The Pro Series Wireless Programmable Thermostat works with the following Honeywell Wireless Relay Boxes: BDR91 HC60NG R6660D R8810A OpenTherm Bridge
- Replaces all Honeywell CM700 and CM900 series wireless thermostats
- Optimum Start & Stop saves energy and money by getting to the correct temperature at the correct time and turning off the heating early if the room temperature is correct.
- Updated user interface provide modern on-screen feedback
- Built-in memory holds the user program indefinitely so that it is never lost even if you remove the batteries
- Easily binds to all existing Honeywell Wireless Relay Boxes. Comes with Instructions on 'How to' for your installation engineer.
- Box Contains: 1x Pro Series 7 Day Programmable Wireless Room Unit 2x AA Alkaline Batteries 1x Wall Mount 1x Stand Mount
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Our Rankings
Hanicks
Hanicks Honeywell-Resideo TotalHome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk3 Replacement) Wireless Room Thermostat & Receiver Kit TTHWFP
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Main Highlights
- The Pro Series Wireless Programmable Thermostat is a BRAND NEW 2021 launched, 7 day programmable room thermostat designed to replace all existing Honeywell CM Series Wireless Thermostats. The 'Pro Series' is made in the UK by Resideo (who were formally part of Honeywell International Inc.) and distributed by Hanicks Ltd.
- The Pro Series Wireless Programmable Thermostat will replace the following Honeywell CM Series products: CM921, CMS921, CMS921B1042 CM927, CMS927, CMS927B1049 CM727, CMS727, CMS727E1016 CM721, CMS721
- The Pro Series Wireless Programmable Thermostat works with the following Honeywell Wireless Relay Boxes: BDR91 HC60NG R6660D R8810A OpenTherm Bridge
- Replaces all Honeywell CM700 and CM900 series wireless thermostats
- Optimum Start & Stop saves energy and money by getting to the correct temperature at the correct time and turning off the heating early if the room temperature is correct.
- Updated user interface provide modern on-screen feedback
- Built-in memory holds the user program indefinitely so that it is never lost even if you remove the batteries
- Easily binds to all existing Honeywell Wireless Relay Boxes
- Box Contains: 1x Pro Series 7 Day Programmable Wireless Room Unit 2x AA Alkaline Batteries 1x Wall Mount 1x Stand Mount
4
Our Rankings
Plumbhub Plumbing and Heating Supplies
Plumbhub-Wireless Programmable Thermostat Replacement for CM927 CM921 CM727 CM721 CMS927B1049 with Relay Box Central Heating Programmer - White
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Main Highlights
- Programmable Thermostat: This digital thermostat allows you to set your desired temperature and schedule for optimal comfort and energy savings.
- Easy Operation: The intuitive controls and clear display make it simple to adjust the temperature or program settings.
- Wireless Remote Sensor: The included wireless sensor detects the temperature in another room for more accurate whole-home heating or cooling.
- Replacement unit for the older versions of CM721 CMS721 CM727 CMS727 CMS727E1016 CM927 CM921 CMS927 CMS927B1049 Wireless Room Thermostat & Receiver
- Energy Efficient: By programming the thermostat to your schedule, you can reduce energy consumption and lower utility bills.
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Our Rankings
Hanicks
Honeywel T4R Wireless 7 Day Programmable Thermostat Y4H910RF4003 (Replaces CM927 CMS927 CM921 CMS921 CM727 CM721) Genuine Part - Hanicks
31% Off
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Main Highlights
- Wireless Programmable Thermostat will replace the following Honeywell CM Series products: CM921, CMS921, CMS921B1042 CM927, CMS927, CMS927B1049 CM727, CMS727, CMS727E1016 CM721, CMS721
- 7Day Programmable Schedule Configure flexible heating plans for each day or use preset 5/2/1-day options, with up to 46 independent time & temperature slots per day
- Wireless Convenience Pre-paired thermostat and receiver with up to 30m range; no binding needed for a straightforward install
- Dual Control Compatibility Works with 24230V on/off systems (boilers, heat pumps, zone valves) and supports OpenTherm boilers via the receiver module
- EnergySaving Smart Features Includes TPI control, optimum start/stop, frostprotection down to 5°C, and holiday mode (199days)
- UserFriendly Design Large backlit LCD, intuitive pushbutton interface, temporary override (12hours), and automatic daylight saving adjustment
- Easy Installation & Maintenance Flip-up wiring terminals, clear LED indicators, battery-powered (2×AA with low-battery alert), wireless relay, and clear wiring labels for quick setup
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