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Honeywell CM921 Product Specification Sheet

Wireless programmable thermostat
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CM921 can be installed without disrupting your room décor
as no wiring connection is required between the room unit
and the boiler
Attractive, slim, ultra-modern styling makes it ideal for
location in any type of home
1-day heating programming
A dynamic text display on the LCD that gives enhanced
feedback to the user / installer
LCD Backlighting to illuminate the display for easier viewing
in low light conditions
Reliable RF communication utilising 868 MHz band with 1 %
duty cycle limit to minimise communication disturbance
Every room unit can be bound with several relay boxes (e.g.
to control several electric heating panels)
Armchair programmed
Holiday button that provides energy savings by reducing
to a constant temperature for 1 to 99 days when people are
on holiday, returning to normal operation (AUTO or
MANUAL) on the day of their return.
EEPROM memory holds the user program indefinitely
OFF position has an integral frost protection setting at
minimum 5°C (installer adjustable) so that pipes in the
house will never freeze in winter.
Communication compatibility with other Honeywell product
such as HR80, HM80 and HCE80.
The CM921 thermostat is designed to provide automatic time
and temperature control of heating or cooling systems in
villas and apartments.
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
(<10A). In combination with other CM921 room units and
HC60NG receivers it can be used to control multi-zone
applications (up to 4 zones).
The radio frequency controlled CM921 system pack consists
of a room unit CMT921A and a relay box R6660D (HC60NG).
No wiring to the room unit is required. The installer only
needs to wire the relay box to the controlled device (e.g.
boiler) and mount the room unit in a suitable location where
RF communication is reliable. The CM921 uses reliable RF
communication technology in the 868MHz band.
The CM921 extra large LCD display, dynamic text display
and controls layout are identical to the CM901 'wired'
thermostat. The unit is ideal for consumers who want reliable
and precise temperature control from a modern looking,
simple to program and easy-to-use product.
CM921 can be used to control a zoning system with up to 4
Maximum system efficiency and extended boiler life due to
unique zoning system synchronisation
Automatic Summer / Winter time change adjusts the time
automatically to daylight saving time.
Standard room units and receiver boxes are used for zoning
applications algorithm
When used with the table top stand the room unit can be
positioned anywhere in the room where RF communication
is reliable
24...230V 10A resistive, 3A inductive SPDT relay provides
compatibility with most domestic central heating systems
reducing the need to stock many different models.
The HC60NG may be surface or wallbox mounted.
Installer Set-Up Mode allows extra functions to be set at the
discretion of the installer to match the consumer
applications and needs:
Pump Exercise
Upper / Lower Setpoint Limit Adjust
Temperature offset
Minimum ON time
Cycle rate
Heat / Cool Operation
Proportional Band Width
Fail-safe mode for communication loss
EN0H 8557 UK07 R0 09/06



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  Summary of Contents for Honeywell CM921

  • Page 1 FEATURES • • CM921 can be installed without disrupting your room décor CM921 can be used to control a zoning system with up to 4 as no wiring connection is required between the room unit zones • and the boiler Maximum system efficiency and extended boiler life due to •...
  • Page 2: Specifications

    CM921 CHRONOTHERM CONTROLS/DISPLAY LAYOUT Room Unit Layout: Day & Date Display Time Display Dynamic Text Display (DTD) Burner On Indicator Battery Low Indicator Temperature Display Temperature Change Buttons Information Enquiry Button Slider Switch Green OK Button Program Buttons Battery Cover...
  • Page 3: Installer Setup

    CM921 CHRONOTHERM INSTALLER SET-UP To enter the installer set-up mode: a) Move the slider switch to the OFF position. b) Press and hold the INFO button and the two program buttons ‘< >’ together. c) The unit will display the first parameter of installer parameter group category 1 (from n.1 to n.19).
  • Page 4: Special Features

    CM921 CHRONOTHERM Special Features Description Setting Optimisation The thermostat will adjust the start time in the morning/afternoon To enable: Set parameter 8:OP (Variable Start so the desired temperature is reached by the start of the program (category 1) to 1.
  • Page 5 Relay 20% on / 80% off Instruction The following parameters are for the control of other Honeywell Wireless products such as Wireless Underfloor Heating controls and Wireless Radiator controls. For more information please contact Honeywell sales. 1 - HR80/HM80 control with own/remote...
  • Page 6: Installation

    INSTALLATION • The CM921 is a radio frequency device and for the best performance should be installed in an open space. • Leave at least 30cm distance from any metal objects including wall boxes and at least 1 metre from any other electrical equipment e.g.
  • Page 7 French & Dutch. Sep 06 ENOH8557 HC60 Spare R6660D1025 Honeywell French Sep 06 ENOH8557 HC60 Spare R6660D1041 Honeywell English (UK) Sep 06 ENOH8557 Honeywell Control Systems Limited Newhouse Industrial Estate Motherwell ML1 5SB United Kingdom EN0H 8557 UK07 R0 09/06...