Honeywell CM721 Thermostat User Manual


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6
How do I change the batteries on the
thermostat when they run out?
Thethermostatconstantlymonitorsthebattery
powerlevel, which typicallylasts forabout 2
yearsbeforeneedingreplaced.Whenthepower
isrunninglowaashing 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settingstobecorrect.
How do I set one temperature for the
whole day?
Tooperateasasimplethermostatwithone
temperature throughout the day, select the
manual operating mode by pressing the
MAN button. Adjust the 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.
FAQ’s
• Automatic Summer/Winter Time Change
The CM721 has a built-in Automatic Summer/Winter Time Change feature that will automatically
adjust the clock forward or backward by one hour for ‘Daylight Saving Time’. This is carried out
on the last Sunday of March and October each year.
• Optimum Start
Optimum Start is a program which ensures that the optimum temperature conditions are
achieved at the required times. This is an Energy Efficiency 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.
‘Using the Features’ OPERATING THE CM721
BDR91 Relay Box Controls Layout
The relay box will normally be found mounted
close to the boiler.
What does it mean when the BDR91
relay box green LED is ON?
The 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 OFF.
When do I need to use the push
button?
You should use the push button to control your
boiler only when the RF communication is lost
(see the Troubleshooting Guide).
Push button
and relay
status LED’s
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