Honeywell CM900 Wireless Installation Guide

About Honeywell CM900 Wireless Installation Guide

The Honeywell CM900 Wireless (CM927 or CM921) is a modern wireless programmable room thermostat based on Honeywell’s proven programming philosophy. To further improve the ease of use, this product includes an extra large LCD display with backlighting and LoT Technology to assist customers during daily use.

The CM927/921 room thermostat communicates with the BDR91 Relay Box on an 868MHz Radio Frequency (RF) band to control a single heating system component such as a boiler, pump or zone valve. Neither product will communicate with other RF products that use different frequencies or communication protocols.

Note: The RF link between the individual room thermostat (CM927/921) and Relay Box (BDR91) in system packs provided by Honeywell is pre-configured at the factory and therefore SHOULD be installed at the same site. This makes the installation process fast and easy, but if products from individual system packs are separated, or mixed with other pre-configured system packs during installations please refer to section 5.1 Binding / Rebinding Procedure to bind the desired units together and allow them to communicate with each other.

Honeywell CM900 Installation Information

As these products communicate using RF technology special care must be taken during installation. The location of the RF components as well as the building structure may influence performance of the RF system. To assure system reliability, please review and apply the information given below.

Within a typical residential building the two products should communicate reliably within a 30m range. It is important to take into consideration that walls and ceilings will reduce the RF signal. The strength of the RF signal reaching the Relay Box depends on the number of walls and ceilings separating it from the room thermostat, as well as the building construction - the diagram below illustrates an example of typical signal strength reduction. Walls and ceilings reinforced with steel or plasterboard walls lined with metal foil reduce the RF signal significantly more.

Once a position is selected for the room thermostat this can be checked using the RF Communication Test mode as described in section 2.2.3 Locating the Room Thermostat. If the position is unsuitable the Relay Box will not respond and an alternative position must be selected.

Locating the Room CM900 Wireless Thermostat

Installing the CM900 Wireless System

Please follow the illustrations and information below in sequence to install the Relay Box and room thermostat correctly. For applications other than gas boilers, enabling special features and to see what other system options are available refer to section 4) Installer Mode.

Installing the CM900 Wireless System

Installing the CM900 Wireless System Relay Box

Installing the Room Thermostat

Power Up

  1. Remove the battery cover and insert the batteries supplied with the room thermostat (2 x AA LR6 Alkaline Batteries).
  2. On the initial power up the available user interface languages will be displayed (only on certain models). Use the or buttons to cycle through the options until the desired language is displayed. Press the green button to confirm the selection.
  3. Set the slider switch to the DATE mode.
  4. Use the or buttons to set the correct day / month / year, pressing the green button to confirm.
  5. Use the or buttons to set the correct time, pressing the green button to confirm.

Readmore and Download Honeywell CM900 Wireless Installation Guide PDF Below

honeywell cm921 manual


Download PDF