Frequently Asked Questions - Honeywell CM921 User Manual

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 lashing
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 settings will be stored but you may
need to adjust the time and date settings to be correct.
How do I set one temperature for the whole day?
To operate as a simple thermostat with one temperature for a period of time, move
the slider switch to the MAN position. Adjust the manual temperature by pressing the
or buttons. This can be set anywhere from 5°C to 35°C in 0.5°C steps. The
thermostat will continue to maintain this temperature until another operating mode is
selected or the temperature is adjusted.
What is Optimum Start?
Optimum Start is a program which ensures that the optimum temperature conditions
are achieved at the required times. This is an Energy Eficiency feature that adjusts
the start time of your heating system depending upon how cold it is. For example,
on cold days your heating system will be started earlier to ensure that your home is
warm when you get up (at the target temperature) and on warmer days the heating
system will be started later to save energy. So, if the Optimum Start Feature is used,
then the time / temperature settings which are entered into the thermostat should
be set to when you want to be warm by and not when you want the heating system
to start.
I want to use the table stand instead of wall mounted bracket. Where can I
position the room unit?
It is important to keep the room unit in a location where reliable RF communication
was proven. Advise your installer where would you like to position the room unit and
he will check if the RF communication is reliable in the selected location(s).
Important: The Room Unit measures the temperature of the room where it is located.
It is important that the placement of the Room Unit within the room is away from;
draughts, direct sunlight and other heat sources. As this is a wireless device certain
objects could interfere with the RF signal - Leave at least 30cm distance from any
metal objects (including wall boxes) and at least 1 metre from any other electrical
equipment eg. radio, TV, PC, etc.