Honeywell Programmable Room Thermostat 24 hour CM921

Product Information

The CM921 uses a feature called TPI to control when the boiler fires. The purpose of this is to prevent wide fluctuation in the room temperature. If the room is more than 1.5 degrees below the set temperature, the boiler runs continuously (controlled by boiler stat). Once the difference is less than 1.5 degrees the stat starts cycling the boiler based on a ten minute period. It will start off at, say, 90% ON 10% OFF and slowly reduce this mix 80/20, 70/30, etc as the room temperature approaches set temperature. This could be why you are finding that the boiler is going on and off all the time. OFF mode has an integral frost protection setting at minimum 5°C (installer adjustable) so that pipes in the house will never freeze in winter Direct replacement for a Honeywell CM927/CMS927/CM727/CM921, if you are unsure about compatibility please call us on 01302 279234. If you take a good look at the Pro Series Wireless Programmable Thermostat, you will see it is nearly identical to Honeywell Home’s T3 Series Thermostat (the user display menu is identical). However, the big difference is that the Pro Series Wireless Programmable Thermostat will bind directly to any existing Honeywell Wireless Relay Boxes, where the T3 Series won’t, so you don’t have the hassle of having to get an installer out to fit this. 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.

Am I correct in thinking that when the combi heating return temperature reaches the temp at which the combi is set at(not the room stat) it will turn the burner off until the temp dips below the the required temp,once all the trvs stop asking for heat? The Pro Series Wireless Programmable Thermostat works with the following Honeywell Wireless Relay Boxes: The Honeywell CM921 is wireless and can be controlled remotely using the Honeywell Total Connect Comfort app, available for iOS and Android devices. This allows users to adjust their heating schedules and monitor their heating systems from anywhere, at any time. The device also features a frost protection mode that helps to prevent pipes from freezing during cold weather.The Pro Series Wireless Programmable Thermostat will replace the following Honeywell CM Series products: Reliable RF communication utilising 868 MHz band with 1 percent duty cycle limit to minimise communication disturbance CM921 can be installed without disrupting your room decor as no wiring connection is required between the room unit and the boiler

Built-in memory holds the user program indefinitely so that it is never lost – even if you remove the batteries 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. Honeywell CM921 Wireless 24Hr Programmable Room Thermostat is p art of the Honeywell Controls Range from Plumbarena. Honeywell are one of the market leaders in heating control technology, providing quality products for domestic comfort.

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The 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. The CM921 thermostat is designed to provide automatic time and temperature control of heating or cooling systems. It can be used as part of a system in conjunction with combi boilers, oil-burners and gas fired boilers, circulation pumps, thermal actuators, zone values and electric heating systems 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 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.