Honeywell thermostat CM921 1 Day Wireless Programmable Thermostat User Manual

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fINE TuNING THE CM921
c. Now choose which one of the following parameters you would like to chang\
e:
 i) Change the time format
  ‘CLOCK  SELECT’  should  be  displayed  on  the  screen  -  press  the    or  buttons to select the preferred time format (12=AM/PM format, 24=24hr format) and  the  display  will  flash,  indicating  a  change  has  been  made.  To  confirm  this change press the green  button.
 ii) Reset the built-in program to the factory default
 Press  the    time  button  once.  The...

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Symptom
Possible Cause
Remedy
The thermostat has a blank LCD screen.
Batteries not installed.
Check to see if there are batteries in the battery compartment and the paper tab has been removed.
Incorrect battery orientation.
Check that the batteries have been installed in the correctorientation.
Exhausted batteries.
Replace with new batteries.
The thermostat shows a flashing 
 symbol on the LCD screen.
Batteries are exhausted and need replacing.
Replace with new batteries.
The thermostat’s LCD display...

13
fA q’s &  TR oublESHoo TING
Symptom
Possible Cause
Remedy
The thermostat’s LCD display works but the heating does not switch on (BDR91 LEDs are off or green one is on).
No power to heating system.
Check that there is power to the heating system.
Program does not call for heat.
Move the slider switch to 
MAN 
and press 
  or to 
increase the temperature a few degrees above the current room temperature. The heating should come on after a few seconds.
Wrong electrical connection.
Call electrical...

14
How do I change the batteries on the CM921 when they run out?
The  thermostat  constantly  monitors  the  battery  power  level,  which  typically  last  for about  2  years  before  needing  replaced.  When  the  power  is  running  low  a  flashing symbol will be displayed on the screen. To change the batteries follow the steps in the above section (‘STEP 1: Installing the Batteries’ on page 3), replacing the used batteries with new ones in step c.
Note: While changing the batteries your program...

15
How do I remove the thermostat from the table stand or wall bracket?
After programming is finished always replace the thermostat back on the wall holder or table stand.
BDR91 Relay Box Controls Layout
What does it mean when the BDR91 relay box green LED is ON?
Green  LED  indicates  normal  operation  of  the  radio  frequency  system.  When  the green LED is ON the boiler is also ON. When the LED is OFF the boiler is O\
FF.
fA q’s &  TR oublESHoo TING
Wall bracketTable stand
Push button and relay...

16
Can I use my CM921 to control my air-conditioning system?
Yes, if your system has been set up correctly you can use your thermostat to control the cooling. To switch the thermostat between heating and cooling modes press the    and   buttons  together  for  5  seconds  in  any  of  the  product  operating  modes (AUTO, MAN or OFF).  The  text  ‘COOLING’  will  be  displayed  for  a  moment  on  the screen to indicate the cooling operation is now active. The factory default program for cooling is...

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1842011077-103 R2