Best Honeywell Cm921 Wireless Thermostat Replacement of 2026

Last updated on 03/04/2026
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Best Choice
1
9.8
Exceptional
Honeywel T4R Wireless 7 Day Programmable Thermostat Y4H910RF4003 (Replaces ‎CM927 CMS927 CM921 CMS921 CM727 CM721) Genuine Part - Hanicks
Hanicks

Honeywel T4R Wireless 7 Day Programmable Thermostat Y4H910RF4003 (Replaces ‎CM927 CMS927 CM921 CMS921 CM727 CM721) Genuine Part - Hanicks

Why we love it
  • Programmable for personalized comfort.
  • Easy wireless setup and installation.
  • Energy efficiency for lower bills.
Main Highlights
  • Wireless Programmable Thermostat will replace the following Honeywell CM Series products: CM921, CMS921, CMS921B1042 CM927, CMS927, CMS927B1049 CM727, CMS727, CMS727E1016 CM721, CMS721
  • 7‑Day Programmable Schedule – Configure flexible heating plans for each day or use preset 5/2/1-day options, with up to 4–6 independent time & temperature slots per day
  • Wireless Convenience – Pre-paired thermostat and receiver with up to 30 m range; no binding needed for a straightforward install
  • Dual Control Compatibility – Works with 24–230 V on/off systems (boilers, heat pumps, zone valves) and supports OpenTherm boilers via the receiver module
  • Energy‑Saving Smart Features – Includes TPI control, “optimum start/stop”, frost‑protection down to 5 °C, and holiday mode (1–99 days)
  • User‑Friendly Design – Large backlit LCD, intuitive push‑button interface, temporary override (1–2 hours), 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
9.8
Exceptional
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Best Value
2
9.6
Superb
Honeywell Home T6 Wired Smart Thermostat - Black - Touchscreen Heating Control with Geofencing, Alexa, Apple & Google - 868 MHZ - Easy Install & App Setup for Combi Boiler & More - CM907 Replacement
Honeywell Home

Honeywell Home T6 Wired Smart Thermostat - Black - Touchscreen Heating Control with Geofencing, Alexa, Apple & Google - 868 MHZ - Easy Install & App Setup for Combi Boiler & More - CM907 Replacement

Why we love it
  • Simple touch-screen interface convenience.
  • Remote control from anywhere.
  • Adapts to your routine.
Main Highlights
  • Smart Scheduling - Customise your heating with a 7-day or 5/2-day schedule, featuring up to 6 daily periods. This Wi-Fi thermostat serves as a smart central heating controller, ensuring optimal comfort and efficiency.
  • Geofencing Technology - Utilises your smartphone's location to conserve energy while you're away and restore comfort upon your return. This programmable thermostat is ideal for a wide range of boiler systems working with or without wifi.
  • Intuitive Interface - Featuring a modern, sleek black screen, the large, easy-to-read touchscreen combined with intuitive navigation buttons allows for quick and effortless adjustments to this wall thermostat's settings and temperature control.
  • Voice Control Ready - Seamlessly integrates with Alexa, Google and Apple ecosystems for convenient management of your thermostat. Features AUTO/MAN/ECO/HOLIDAY modes to suit your lifestyle and enhance energy efficiency.
  • Extensive Compatibility - Easy to install, this versatile wired thermostat for central heating supports 24-230V on/off OpenTherm appliances, including gas boilers, combi boilers, and heat pumps, ensuring compatibility and efficiency across various systems.
9.6
Superb
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3
9.5
Superb
Honeywell-Resideo Totalhome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk 3 Replacement) Wireless Room Thermostat & Receiver TTHWFP - Hanicks
Hanicks

Honeywell-Resideo Totalhome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk 3 Replacement) Wireless Room Thermostat & Receiver TTHWFP - Hanicks

Why we love it
  • Replaces all CM Honeywell thermostats.
  • Optimum Start & Stop feature.
  • Long-lasting built-in memory.
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
9.5
Superb
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4
9.4
Superb
Adept-Honeywell Wireless Programmable Thermostat Replacement for CM927 CM921 CM727 CM721 CMS927B1049 with Relay Box Central Heating Programmer - White
Adept Technology

Adept-Honeywell Wireless Programmable Thermostat Replacement for CM927 CM921 CM727 CM721 CMS927B1049 with Relay Box Central Heating Programmer - White

Why we love it
  • Offers seamless thermostat transition.
  • Enhanced user-friendly interface.
  • Promotes energy and cost savings.
Main Highlights
  • The Adept Wireless Programmable Thermostat, a state-of-the-art replacement unit for the Honeywell CM927, CMS927, and CMS927B1049 Wireless Room Thermostats. Designed with the latest technology, this thermostat offers a seamless transition from your existing Honeywell CM Series Wireless Thermostats, ensuring consistent temperature regulation and enhanced user experience.
  • 7-Day Programmability: Customize your heating schedule for every day of the week, ensuring optimal comfort and energy efficiency.
  • Compatibility: Directly replaces a range of Honeywell CM Series products, including CM921, CMS921, CMS921B1042, CM927, CMS927, CMS927B1049, CM727, CMS727, CMS727E1016, and CM721.
  • Advanced RF Protocol: Utilizes the 868MHz 'Ramses 2' RF protocol for reliable communication and performance.
  • User-Friendly Interface: While it mirrors the user display menu of Honeywell Home's T3 Series Thermostat, it offers unique features like the absence of the +1hr function and flame icon during heating demand.
9.4
Superb
Amazon Logo
5
9.2
Superb
Hanicks Honeywell-Resideo TotalHome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk3 Replacement) Wireless Room Thermostat & Receiver Kit TTHWFP
Hanicks

Hanicks Honeywell-Resideo TotalHome CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk3 Replacement) Wireless Room Thermostat & Receiver Kit TTHWFP

Why we love it
  • Replaces all Honeywell wireless thermostats.
  • Cuts energy costs effectively.
  • Holds user program indefinitely.
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
9.2
Superb
Amazon Logo
6
9.1
Superb
Hanicks Honeywell-Resideo DT92E1000 Wireless Digital Room Thermostat & Receiver Direct Replacement for DT92 DT92E DTS92E1020
Hanicks

Hanicks Honeywell-Resideo DT92E1000 Wireless Digital Room Thermostat & Receiver Direct Replacement for DT92 DT92E DTS92E1020

Why we love it
  • Wire-free installation.
  • Advanced intelligent heating control.
  • Intuitive user interface.
Main Highlights
  • Direct replacement for DT92 DT92E1000 - the thermostat can be paired to the original BDR91 receiver for a wire-free installation
  • Comes with Wireless thermostat, relay box, table stand, 2 x AA batteries and instruction manual
  • Reliable, encrypted, two-way wireless communication between the thermostat and the wireless receiver box
  • Utilizes an advanced, self-learning algorithm for intelligent heating control, ensuring more efficient boiler control. One-touch energy-saving ECO button which gives timed setback or boosts temperatures to reduce energy demand, as well as an ‘OFF’ setting that can be used for frost or hypothermia protection
  • Suitable for standard & combi boilers, electric heating (On/Off; Relay: 24…230V 5(3)A), underfloor heating, cooling systems or heat pumps
  • Intuitive user interface for efficient control, no learning curve or programming, easy two-wire wiring, volt-free connections (the receiver to the device to control). Ideal for use with combi boilers or heating zones
9.1
Superb
Amazon Logo
7
9.0
Superb
Save 33%
TotalHome - Wireless Room Thermostat & Receiver (Honeywell/Resideo) CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk2 Replacement) (TTHWFP)
TotalHome

TotalHome - Wireless Room Thermostat & Receiver (Honeywell/Resideo) CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk2 Replacement) (TTHWFP)

33% Off
Why we love it
  • Reliable Honeywell/Resideo design.
  • Seamless model replacement.
  • Trusted brand performance.
Main Highlights
  • TotalHome is designed and manufactured by Honeywell/Resideo.
  • Direct replacement for the Honeywell models CM927, CMS927, CM727, and CM921
9.0
Superb
Save 33%
Amazon Logo
8
8.8
Excellent
LavaTap Pro Honeywell Wireless Programmable Thermostat CM927 CM921 CM727 Replacement 7 Day Central Heating Programmer Boiler Plus Compliant White Standard
LavaTap

LavaTap Pro Honeywell Wireless Programmable Thermostat CM927 CM921 CM727 Replacement 7 Day Central Heating Programmer Boiler Plus Compliant White Standard

Why we love it
  • Seamless replacement for various models.
  • Maintains program after battery removal.
  • Features intelligent heating control.
Main Highlights
  • Made And Supported By Honeywell Resideo: Manufactured and supported providing recognised product backing and technical support
  • Direct Replacement Compatibility: Designed as a replacement for Honeywell CM927 CM921 CM727 CMS727 CMT727 CMS921 CMS927 and older CM721 CMS721 CMS727E1016 CMS927B1049 wireless room thermostat and receiver models
  • Wireless System Requirement: Suitable for wireless Honeywell heating systems using a relay box and on off control not suitable for wired thermostats or OpenTherm only installations
  • Pre Bound And BDR91 Compatible: Supplied pre bound with relay box and can also be bound to Honeywell BDR91 relay box with setup guidance and QR video support
  • 7 Day Programmer Boiler Plus Compliant: 7 day programmer with four time schedules per day intelligent heating control and Boiler Plus compliance to help meet Part L regulations
  • Complete Kit With Memory Retention: Includes wireless thermostat relay box table stand AA batteries and instructions with built in memory retaining programme settings during battery change
8.8
Excellent
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9
8.7
Excellent
Plumbhub-Wireless Programmable Thermostat Replacement for CM927 CM921 CM727 CM721 CMS927B1049 with Relay Box Central Heating Programmer - White
Plumbhub Plumbing and Heating Supplies

Plumbhub-Wireless Programmable Thermostat Replacement for CM927 CM921 CM727 CM721 CMS927B1049 with Relay Box Central Heating Programmer - White

Why we love it
  • Programmable for energy savings.
  • Easy and intuitive controls.
  • Accurate whole-home temperature.
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.
8.7
Excellent
Amazon Logo
10
8.7
Excellent
Save 28%
Honeywell Home T3 Wired Smart Thermostat Kit - Wall Thermostat with Flexible Programming & ECO Mode - Battery Operated, Compatible for Combi Boilers & Heat Pumps - CM907 Replacement (T3C110AEU)
Honeywell Home

Honeywell Home T3 Wired Smart Thermostat Kit - Wall Thermostat with Flexible Programming & ECO Mode - Battery Operated, Compatible for Combi Boilers & Heat Pumps - CM907 Replacement (T3C110AEU)

28% Off
Why we love it
  • Adapts to personal comfort needs.
  • Responsive and user-friendly navigation.
  • Efficient energy-saving features.
Main Highlights
  • Versatility & Compatibility - This smart thermostat is designed to work seamlessly with 24-230V on/off and OpenTherm appliances such as combi boiler systems, heat pumps, gas boilers, and zone valves, making it suitable for various environments.
  • Intuitive 7-Day Scheduling - Experience flexible programming options with this smart central heating controller. Set up to 6 independent time slots per day, easily copy schedules across days, and switch effortlessly between OFF, Manual, Eco and Auto modes.
  • Modern, Minimalistic Design - Featuring a large backlit screen and an intuitive interface, this boiler thermostat is easy to operate and allows you to review current settings at a glance. Comes with a 2-year warranty.
  • Smart Home Integration - Connect this digital thermostat to your home heating system for seamless control. The T3 Series is the top choice for heating professionals and customers too.
  • Efficient, Reliable Operation - This wall thermostat features a self-learning TPI algorithm that adapts to your space. Battery-powered for consistent performance, it also replaces the CM907 and includes automatic time clock adjustment. (2 AA batteries included).
8.7
Excellent
Save 28%
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Related Deals You Might Like for Honeywell Cm921 Wireless Thermostat Replacement

📊We scanned 250 products
🔍
We reviewed the most relevant Honeywell Cm921 Wireless Thermostat Replacement offers across Amazon and leading retailers, covering major brands and models. Our shortlist features trusted names like Hanicks, Honeywell Home, Adept Technology, TotalHome, LavaTap, Plumbhub Plumbing and Heating Supplies, known for dependable quality and smart design.
⭐
To determine today's best Honeywell Cm921 Wireless Thermostat Replacement, we analysed 1251 real customer and expert reviews, focusing on satisfaction, real-world performance and long-term reliability. We also weigh each review's relevance, authenticity and freshness for a fair comparison.

What we concluded:

🏆 #1
Honeywel T4R Wireless 7 Day Programmable Thermostat Y4H910RF4003 (Replaces ‎CM927 CMS927 CM921 CMS921 CM727 CM721) Genuine Part - Hanicks

Our overall winner is Honeywel T4R Wireless 7 Day Programmable Thermostat Y4H910RF4003 (Replaces ‎CM927 CMS927 CM921 CMS921 CM727 CM721) Genuine Part - Hanicks by Hanicks. It stands out for the right balance of quality, performance and value.

✨ What sets it apart:
✓Programmable for personalized comfort.
✓Easy wireless setup and installation.
✓Energy efficiency for lower bills.
💎 Best Value
Honeywell Home T6 Wired Smart Thermostat - Black - Touchscreen Heating Control with Geofencing, Alexa, Apple & Google - 868 MHZ - Easy Install & App Setup for Combi Boiler & More - CM907 Replacement

The best value for most shoppers is Honeywell Home T6 Wired Smart Thermostat - Black - Touchscreen Heating Control with Geofencing, Alexa, Apple & Google - 868 MHZ - Easy Install & App Setup for Combi Boiler & More - CM907 Replacement by Honeywell Home, with consistently high satisfaction across expert and customer reviews.

💰 Best Deal
TotalHome - Wireless Room Thermostat & Receiver (Honeywell/Resideo) CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk2 Replacement) (TTHWFP)

The strongest deal right now for Honeywell Cm921 Wireless Thermostat Replacement is TotalHome - Wireless Room Thermostat & Receiver (Honeywell/Resideo) CM927 CM921 CM727 CM721 CMS927 CMS927B1049 (Mk2 Replacement) (TTHWFP) at TotalHome, currently at 33% off.

🔄Our Honeywell Cm921 Wireless Thermostat Replacement ranking is updated regularly to reflect new releases and price changes—check back for the latest picks and deals.