Has anybody come across this problem? Maybe I have to accept I need to have a new receiver and thermostat installed but I just wanted to find out what the problem is with mine first!

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 to independent merchants via a national merchant wholesaler. Resideo (Honeywell Home) is the same manufacturer who made the CM700 & CM900 Series Thermostats. The Pro Series Programmable Wireless Thermostat replaces the discontinued Honeywell CM927/CMS927/CMS927B1049. This is a 7 day wireless programmable room thermostat designed to control your heating system efficiently, providing comfortable temperatures when you are at home and energy savings when you are away. With wireless communication there is no need to provide a wired connection between the thermostat and boiler. Wireless connection to the boiler allows you to mount the Chronotherm in your room without disruptionThe Honeywell CM921 is a programmable thermostat designed for use in homes and small businesses in the United Kingdom. It features a clear digital display and simple controls, making it easy to set schedules for heating and cooling systems. The device is compatible with a wide range of boilers, making it versatile and suitable for different types of heating systems. Pro Series Wireless Programmable Thermostat – Replaces Honeywell CMS927 & CMS921 Wireless Programmable Room Thermostats Built-in memory holds the user program indefinitely so that it is never lost – even if you remove the batteries

This is a Pro Series Wireless Programmable Thermostat ONLY and does not include a Wireless Relay Box! The Honeywell CM921 Wireless 24Hr Programmable Room Thermostat series of Wireless Programmable Thermostats is designed to provide wireless time and temperature control to heating or cooling systems in domestic and light commercial buildings. The slim, ultra modern design complements the large LCD screen with the Line of Text (LoT) display and one function button to ensure simplified programming and operation for all users.

Pro Series Programmable Wireless Thermostat Box contains:

The Pro Series Wireless Programmable Thermostat will replace the following Honeywell CM Series products: Direct replacement for a Honeywell CM927/CMS927/CM727/CM921, if you are unsure about compatibility please call us on 01302 279234. Pro Series Wireless Programmable Thermostat | Direct Replacement for Honeywell CM927/CMS927/CMS927B1049 Wireless Programmable Room Thermostat Pro Series Programmable Wireless Thermostat Box contains: 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. The Honeywell CM921 can be programmed for up to six different time periods per day, allowing users to tailor their heating schedules to their individual needs and preferences. The device also features a holiday mode that allows users to set a lower temperature when they are away from home for an extended period of time, helping to save energy and reduce costs.