(Made by Honeywell)
42008847-021 R1
1234567
 USER GUIDE
The Chronotherm Modulation is designed to provide automatic time and 
temperature control of heating systems. These instructions explain how to 
program and operate your Chronotherm Modulation.
Chronotherm Modulation can be used with all OpenTherm® compatible boilers. 
The OpenTherm® compatible boilers are marked with OT logo shown below.
Chronotherm Modulation is a programmable thermostat that controls your heating 
system so that you can have comfortable temperatures when you are at home and 
energy savings when you are out. To ensure that your heating system is operating 
in most efficient way Chronotherm Modulation not only switches the boiler on and 
off but also modulates the flame to finely match the heating output of the heating 
appliance to the current heat demand.
To maximise energy efficiency Chronotherm Modulation has build -in Adaptive 
Intelligent Recovery function Instead of switching the heating on at the set time 
every day, the controller will delay the start time to the latest possible moment, so 
that unnecessary heating is avoided. All you have to do is set the time by which 
you want to be warm and Chronotherm Modulation will then decide when to turn 
the heating on.
1 Day button allows you to set correct day of the week.
2 The display continuously shows information about time, day of the week and
temperature. The Energy meter allows you to see the current firing rate of the 
boiler. A radiator or tap symbol is shown when boiler is servicing central 
heating or domestic hot water.
3 These buttons are used to adjust the temperature level. You can operate
these buttons also when the flap is closed.
4 “
” Enquiry button is used to display the set room temperature level and the 
outside temperature (only if the outside temperature sensor is connected to 
your boiler).
5 The holiday function allows setting of a setback temperature for a period of
maximum 99 days. The same function can also be used as timed program 
override providing energy savings or extended comfort period.
6 These buttons are used to program up to six temperature changes per day.
7 Slider position defines the operating mode. When slider is set to AUTO the
Chronotherm will operate according to the program.
8 Time adjustment buttons are used for clock and temperature change
settings.
9 The copy button allows you to copy the time/temperature program to the next
day.
 SPECIAL FUNCTIONS
Modulating control
The Chronotherm Modulation continuously adapts the firing rate of the boiler to 
the required heat demand. This results in a very accurate control of the room 
temperature. The modulating control is only possible if the heating appliance is 
supporting OpenTherm® communications.
OpenTherm
®
 communication
The Chronotherm Modulation exchanges information with the heating appliance 
using OpenTherm® two-way communication protocol.
NOTE: The amount and type of information that can be displayed as well as 
appliance specific information codes may vary.
Refer to the user manual of the appliance for this specific information.
Optimizing through the intelligent adaptive recovery (AIR) feature.
To achieve the required temperature in the house we typically set the on time for 
the heating system earlier than required. In this way we can be sure that we will 
have the comfortable temperature when we wake up. As we never can guess 
precisely when the heating should come on we tend to stay on the save side 
setting the on time earlier then required. Consequently we have to pay for keeping 
the house at comfort temperature longer then necessary. The Chronotherm 
Modulation solves this problem completely. It checks every day how much time is 
required to heat up your home. Using this data the Chronotherm Modulation 
calculates the precise moment when to start the heating up the next day to 
achieve comfort temperature exactly when you want it. Consequently you do not 
have to take the warm up time into account when programming. The Chronotherm 
Modulation activates adaptive intelligent recovery function before every 
programmed temperature level increase.
NOTE: After installation Chronotherm will require a couple of days to learn how to 
calculate ON times for a particular house.
Program up to six time/temperature periods per day.
You have the possibility to set 6 different periods for each day of the week. The 
time/temperature periods are marked with numbers 1 to 6.
The start time and temperature level for each period is programmable within the 
temperature setting range of 5 to 30°C.
Backup during power supply failure
Your Chronotherm Modulation operates without batteries. The power is supplied 
through the communication connection. In case of the mains power loss a 
rechargeable backup power supply is sufficient to keep the program and the clock 
settings for at least 8 hours. If the backup supply is exhausted the display will be 
blank and the individual program will be deleted. After the mains supply has been 
reestablished the factory program will be activated and the display will flash at
12.00. It will take between 10 and 60 minutes (dependant on the operating 
conditions) to charge the backup supply.
The energy meter
If the burner of the boiler is energized, a bar of flames will be shown on the left 
side of the display. This allows you to check at all times at what firing rate your 
boiler is operating. (The percentages in the above graph are indicative only. 
Dependant on the modulation band of your boiler the in between values may vary)
The radiator or tap symbol indicates if energy is being used for central heating or 
the domestic hot water (if applicable).
Unique holiday/timer function
The holiday button allows you to override your normal temperature profile and set 
the fixed temperature level for a defined time. You can set the required 
temperature for as long as 99 days or as short as 1 hour.
Intelligent DHW control
If you own a boiler that also provides hot water (combi boiler) then the 
Chronotherm Modulation can provide additional savings.
In the FROST PROTECTION or HOLIDAY/TIMER function, the Chronotherm 
Modulation will switch off the DHW function or (dependant of the appliance) will 
switch to a savings mode. In this way the DHW storage will not be kept on a high 
comfort temperature if this is not necessary.
If desired it is possible to switch off the DHW during the night setback period. Your 
installer can set this for you.
NOTE: This function is only available if your boiler is suitable for this 
communication. Consult the user manual of the boiler or ask your installer.
 CONTROLS LAYOUT
 PROGRAMMING YOUR THERMOSTAT
Before you start programming
You can program your Chronotherm Modulation only if the mains supply of the 
boiler is switched on, the electrical connection to the boiler is made and the 
thermostat has been mounted on the wall plate. When the power for the 
thermostat is present the display will be activated and the clock will start.
NOTE: Operate the keypad with your fingertips only. Sharp objects like pens or 
pencils can damage the keypad.
How do I set the time and the day?
1. Move the slider to DAY/
 position. The time and the 
day marker will flash indicating that they can be 
changed.
2. Press the  + or – button until the correct time is 
displayed. Each button press will change the time by 
one minute and stop the display from flashing. 
Holding the button down for a few seconds will 
change the time slowly at first, then quickly.
3. Press DAY 1..7 button until the day marker is 
positioned under the correct day (DAY1 is Monday). 
Each button press moves the day marker by one 
day.
How do I get started with the built-in temperature program?
Move the slider to the AUTOmatic position
The Chronotherm Modulation will now control your heating system using the builtin temperature program.
You now have a choice of two methods to set the program for the next day
6.a Press the COPY DAY button to copy Monday’s program into Tuesday. To set 
several days of the week to the same program, press the copy day button 
repeatedly.
6.b Press the DAY 1..7 button to step the day marker to Tuesday (Day 2). The 
program for Tuesday can be then set as described in steps 2 to 5.
Programs for Wednesday (Day 3) to Sunday (Day 7) can be set in the same 
day, using the DAY 1..7 button.
7. Move the slider to AUTOmatic position when you have completed steps 6a or 
6b. The Chronotherm Modulation will now control the room temperature to 
match your program.
What do I do if I do not want to use all 6 temperature changes times?
The built-in program uses only 4 temperature change times as indicated in section 
“How do I get started with the built-in temperature program?”
The unwanted change times can be deleted by moving the slider to PROGRAM 
position and holding the appropriate button (1, 2, 3, 4, 5, 6) for a few seconds. The 
change time will be removed and the display will show dashes instead of time/ 
temperature display.
Deleted temperature change times can be brought back by pressing the 
appropriate (1, 2, 3, 4, 5, 6) button and then TEMPerature 
 or  button (with
slider set to PROGRAM position).
 OPERATING YOUR THERMOSTAT
With the operating mode slider in AUTOmatic position Chronotherm Modulation 
will control the room temperature to match your heating program
Manual Override
When the slider is in AUTOmatic position the temperature can be adjusted 
temporarily by pressing the TEMPerature 
 or  button. The temperature will
return to program at the next temperature change time.
How do I set the temperature for the whole day?
To operate as a simple thermostat with one temperature throughout the day, move 
the slider to the MANUAL position. Adjust the manual temperature by pressing 
the TEMPerature 
 or  button. The manual temperature can be set anywhere
from 5°C up to 30°C.
How can I switch the Chronotherm Modulation off?
Move the slider to the  position. Thermostat has built-in frost protection feature, 
so that if temperature will drop below 7°C it will automatically switch back on to 
prevent pipes from freezing.
NOTE: The frost protection activation level can be adjusted from 7°C to 10°C 
using TEMPerature 
 or  button.
How do I check the programmed temperature?
In normal operation the temperature displayed is the actual room temperature. To 
check the programmed temperature, press the i button once.
NOTE: During upward temperature level change the temperature on the display 
may not correspond with the programmed level of the current period. The reason 
is that during warm up the thermostat gradually increases the temperature level 
setting to the next temperature change level. During the warm up period the 
number of the next period is flashing
How can I check the outside temperature?
Press the 
 button twice. The outside temperature code T3 will be displayed
together with current outside temperature value.
NOTE: This option is available only if the heating appliance provides the outside 
temperature information to the thermostat.
I am going on holiday for a couple of weeks. How do I save energy when I 
am away?
1. Move the slider to the operating position you require on returning from your
holiday (AUTOmatic or MANUAL)
2. Press the 
 (HOLIDAY) button to display the holiday days counter and the
temperature
3. Press the 
+ or – button to set the holiday time (1-99 days). An extra flashing 
day marker shows the day of the week representing the holiday return day. 
Today is counted as the first day of holiday. The holiday temperature is set 
using the TEMPerature 
 or  button. At midnight of the last day of your 
holiday the thermostat will return to the normal control as set by the slider 
position.
These two buttons can 
also be used when the 
flap is closed
Off Low fire 40 60 80 100%
OpenTherm® communication
Monday to Friday
Program 1 1 2 3 4 5 6
Time 07:00 09:00 - - 19:00 23:00
Temperature 19°C 15°C - - 21°C 15°C
Saturdy and Sunday
Période 1 2 3 4 5 6
Time 08:00 - - - - 23:00
Temperature 19°C - - - - 15°C
How do I set my own temperature program for each day of the week?
1. Move the slider to PROGRAM position. You will see 
the first temperature change time and temperature 
level for Monday’s program (the two small arrows 
are displayed only when the programmed 
temperature level is shown). The flashing display 
indicates that you can make changes.
2. Press the 
 + or – button to adjust the first 
temperature change time. Holding the button down 
will change the time quickly. The change time can 
be set in 10 minutes steps from 03:00 in the 
morning. The change time can be adjusted to any 
time up to 02:50 on the next morning, so you can 
maintain evening temperature after midnight.
NOTE: If you attempt to move a change time past 
the next change time, both times will be moved.
3. Press the TEMPerature  or  button to adjust the 
first temperature level. Holding the button down will 
change the temperature quickly. The temperature 
can be set in 0.5°C steps from 5°C to 30°C
4. Press the program 2 button to display the second temperature change time and 
temperature level for Monday. Set these by pressing the 
 + or – button and
the TEMPerature 
 or  button.
5. The remaining temperature changes for Monday can be displayed by pressing 
program buttons 3, 4, 5 and 6 and adjusted by using 
 + or – button and the
TEMPerature 
 or  button. (if you don’t want to use all temperature change 
times 2, 3, 4, 5 and 6 refer to the next question “What if I don’t want to use all 
6 time temperature change times”)