Buderus RC20 User manual

7 747 006 217 – 08/2006 GB For the user
Please read carefully before use.
Operating instructions
RC20 room controller

Contents
2 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Safe handling of your RC20 . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1 Correct use. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2 Please observe these notes. . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.4 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.5 Other notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 First steps with your room controller . . . . . . . . . . . . . . . . . 6
3.1 Controls. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2 Quick reference guide . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4 The functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
4.1 Changing the room temperature directly. . . . . . . . . . . . . . . .10
4.2 Setting the room temperature . . . . . . . . . . . . . . . . . . . . . .14
4.3 Heating domestic hot water. . . . . . . . . . . . . . . . . . . . . . . .17
4.4 Setting day and time . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
4.5 What is a heating program? . . . . . . . . . . . . . . . . . . . . . . .20
4.6 Heating program selection . . . . . . . . . . . . . . . . . . . . . . . .21
4.7 Heating program summary . . . . . . . . . . . . . . . . . . . . . . . .22
5 Information on setting the programming unit . . . . . . . . . . . 23
5.1 What does the RC20 room controller regulate?. . . . . . . . . . . . 23
5.2 Control modes for the heating control unit . . . . . . . . . . . . . .24
5.3 Tips on energy-efficient heating . . . . . . . . . . . . . . . . . . . . .26
6 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
6.1 Frequently asked questions . . . . . . . . . . . . . . . . . . . . . . .27
6.2 Fault displays . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
6.3 Resetting faults (reset). . . . . . . . . . . . . . . . . . . . . . . . . . . 30
7 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Introduction 1
3
We reserve the right to make any changes due to technical modifications.
Operating instructions RC20 room controller • Issue 08/2006
1Introduction
The RC20 room controller makes it easy to operate your Buderus
heating system with Energy Management System (EMS). The
heating system is controlled in such a way that you benefit from
optimum heating comfort and minimum energy consumption.
The RC20 room controller is factory-set for immediate use. You
can modify these settings, such as the heating program for
example, and match them to your requirements.
Special functions help you to save energy, without sacrificing your
personal comfort. For example, simply pressing a key starts
domestic hot water heating.
The design and operation of this product conforms to European
Directives and the supplementary national requirements. Its
conformity is demonstrated by the CE Declaration of Conformity.
You can view the Declaration of Conformity on the Internet at
www.buderus.de/konfo or request a copy from your local
Buderus office.

Safe handling of your RC202
4 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
2 Safe handling of your RC20
The RC20 room controller has been developed and built in
accordance with currently recognised standards and safety
requirements. However, dangers or material losses may arise if it
is used improperly.
zYou should therefore only operate the heating system as
intended and when it is in perfect working order.
zPlease read these instructions carefully.
zAlways observe the safety instructions to prevent injury and
material losses.
2.1 Correct use
The RC20 room controller may only be used to operate and control
Buderus heating systems in houses or apartments.
The boiler must be equipped with EMS (energy management
system) or UBA1.x (universal burner control). We recommend that
the heating system is always operated using the room controller
(only emergency operation possible without room controller).
2.2 Please observe these notes
USER NOTE
zIn an emergency isolate the heating system from the mains
supply using the emergency stop switch outside the boiler
room or by removing the main fuse.
zCall in your local heating contractor to remedy any faults in
your heating system immediately.

Safe handling of your RC20 2
5
We reserve the right to make any changes due to technical modifications.
Operating instructions RC20 room controller • Issue 08/2006
2.3 Cleaning
zThe room controller should only be cleaned with a damp cloth.
2.4 Disposal
zDispose of packaging in an environmentally responsible
manner.
zDispose of old components in an environmentally
responsible manner through an approved organisation.
2.5 Other notes
Assembly, maintenance and repairs, as well as fault diagnosis,
may only be carried out by a heating contractor.
CAUTION!
SYSTEM DAMAGE
through frost.
The heating system can freeze up in cold weather if it has been
switched off.
zLeave the heating system switched ON constantly.
zIn case of fault shutdown, try to remedy the fault by resetting
or notify your heating contractor.
USER NOTE
All modifications and settings made on the room controller must
consider the implications for the heating system.
Never open the housing of the programming unit.

First steps with your room controller3
6 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
3 First steps with your room controller
3.1 Controls
Fig. 1 RC20 controls
Item 1: Display
Item 2: Keys for basic functions with LEDs
Item 3: Rotary selector for changing values and temperatures
or for navigating through the menus
Item 4: "Prog" and "Time" keys
Item 5: Flap; covers the "Prog" and "Time" keys
Keys for basic functions
(Fig.1,Item2)
Keys for extended functions
(Fig.1,Item4)
"AUT" key (automatic) "Time" key
"Day mode" key "Prog" key (program)
"Night mode" key
"DHW" key
4
3
2
5
1

First steps with your room controller 3
7
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Operating instructions RC20 room controller • Issue 08/2006
Display (Fig. 1, Item 1)
The display shows set and actual values and temperature, e.g. the
actual room temperature (standard display in factory setting).
The display shows four dashes if you try to change a value that
cannot be modified of if no setting is possible.
Fig. 2 Explanation of the display elements
Item 1: Day (1 = Mo, 2 = Tu,... 7 = Su)
Item 2: Set or actual value or temperature
Item 3: "Temperature in °C" display
Item 4: "Outdoor temperature" display (only in conjunction with a
programming unit, for example RC30/RC35, see page 23,
RC20 as remote control)
Item 5: "Actual room temperature" display
Item 6: Display:
a) Room temperature can now be adjusted or
b) Room temperature has temporarily changed (temporary room
setting, see section 4.2.2, page 15)
Item 7: "Summer mode" display (only in conjunction with a programming
unit, e.g. RC30/RC35, that provides a summer mode for the
heating system)
Item 8: Operating status symbols (see Tab. 1, page 8)
6
3
1
7
2
4
5
8

First steps with your room controller3
8 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
LEDs (Fig. 1, Item 2, page 6)
The green LEDs and the symbols in the display provide
information about the current operating status:
Flap (Fig. 1, Item 5, page 6)
To open the flap, pull the flap on the recessed grip on the left-hand
side towards you. Opening the flap activates a switch. The flap
covers the keys for setting the time and the day, as well as the
heating program selection.
LED Symbol Operating status
"Automatic
mode"
The symbol lights up when automatic mode
(heating program) is active. The "Day mode" or
"Night mode" symbol is also illuminated. 2)
If the holiday function is active, only the "AUT"
symbol is illuminated.
"Day
mode"
The symbol lights up in normal heating mode
(day mode).
"Night
mode"
The symbol lights up in setback heating mode
(night mode).
"DHW"
The symbol lights up if the DHW temperature
falls below the set value. 1)
The symbol is not illuminated if the DHW
temperature is within the required temperature
range or if there is no DHW heating function
installed in the EMS. 1)
The symbol flashes when hot water is being
heated by the "DHW single charge" function. 1)
"Auto/day/
night
mode"
"Temporary room setting" operating mode
Room temperature has temporarily changed
(see section 4.2.2, page 15) The changed
setting is retained until the heating system
changes the operating mode (e.g. to night
mode).
Tab. 1 Operating status
1) On boilers with UBA 1.x the LED never lights up.
2) On boilers with UBA 1.x only one LED lights up.

First steps with your room controller 3
9
We reserve the right to make any changes due to technical modifications.
Operating instructions RC20 room controller • Issue 08/2006
3.2 Quick reference guide
Setting temperatures (Chapter 4, page 10)
Functions (Chapter 4, page 10)
Keys Function Factory
setting
Setting
Range System
Temperature for
automatic mode
(day/night)
21/17 °C as for day/
night
Temperature for
day mode
(manual mode)
21 °C 6 – 30 °C
Temperature for
night mode
(manual mode)
17 °C 5 – 29 °C
Return to Automatic mode after changing the day or night
temperature
Change temperature temporarily ("temporary room
setting" )
Pressing a key cancels the temporary room setting and
activates the selected mode.
DHW temperature 60 °C 30 – 60
(80) °C
Flap closed
+
+
+
+
Keys Function Page
Set the time page 19
Select a heating program page 21
Flap open
+
+

The functions4
10 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
4 The functions
This chapter describes how to change room and DHW
temperatures, the advantages of automatic mode, how to make
effective use of manual mode, etc.
The functions are controlled by pressing a key on the right-hand
side of the RC20 and turning the rotary selector.
4.1 Changing the room temperature directly
If all of your accommodation is too cold, raise the room
temperature using the rotary selector, and leave the
thermostatic radiator valves unchanged.
Example: setting the room temperature
Set the required room temperature by turning the rotary selector.
USER NOTE
The temporarily changed setting is retained until you press an
operating mode key or until the heating system changes the
operating mode (e.g. to night mode).
See section 4.2, page 14 for information on other ways of
changing the room temperature.

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11
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Operating instructions RC20 room controller • Issue 08/2006
4.1.1 Selecting the operating mode
You may operate the RC20 room controller in two ways:
– in automatic mode
– in manual mode
4.1.2 Selecting automatic mode
Generally, homes are heated less at night than during the day. The
room controller changes over automatically between day mode
(standard heating mode) and night mode (setback heating mode).
This makes changing the thermostatic radiator valves in the
morning and evening superfluous.
The times at which the heating system changes from day to night
mode – and vice versa – are factory-set via heating programs
(see section 4.5 "What is a heating program?", page 20).
However, you can also select a different heating program from the
preset standard programs.
The heating program raises or lowers the room temperature at
fixed times. The time at which the system changes from night to
day mode (and vice versa) is known as the "switching point".
Fig. 3 Changeover between day and night mode at fixed times
21 °C
17 °C
day mode
night mode 5:30 22:00

The functions4
12 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
Example: activating automatic mode
The display shows the "AUT" symbol; automatic mode is active.
While the "AUT" key is held down, the arrow symbol lights up and
the display shows the set room temperature for automatic mode.
When the "AUT" key is released, the display shows the standard
display (e.g. the actual room temperature) again. In addition, either
the "Day mode" or "Night mode" symbol is illuminated. This
depends on the set times for day and night mode.
Press "AUT".
USER NOTE
If the RC20 is installed as a remote control unit (see section 5.1
"What does the RC20 room controller regulate?", page 23): you
may find during the in-between seasons of spring and autumn that
your home feels too cold, even though the heating system is in
summer mode because of the outside temperature (DHW heating
only). In this case, choose manual mode to run the heating one
hour at a time.
The room temperature will be controlled if the RC20 is the sole
programming unit. As the outside temperature is ignored, there
can be no summer/winter changeover.

The functions 4
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Operating instructions RC20 room controller • Issue 08/2006
4.1.3 Selecting manual mode
For example, if you want the heating to run for longer in the
evening or not quite as early in the morning, you can also select
the day and night mode manually. There are two temperatures for
manual day and night mode. You can use day mode to run the
heating on cool days in summer mode (only if the RC20 is installed
as a remote control unit, see section 5.1, page 23).
Press the "Day mode" button to switch to manual mode.
The display will show the set room temperature for day mode. The
"Day mode" symbol lights up in the display. Now your heating
system is in constant day mode (standard heating mode).
Press the "Night mode" button to switch to manual mode.
The display will show the set room temperature for night mode.
The "Night mode" symbol lights up in the display. Now your heating
system is in constant night mode (setback heating mode), and
operates at a lower room temperature.
USER NOTE
If you have selected manual mode, the selected heating
program will no longer be active (for example no night setback
of the room temperature).
To return to automatic mode, press "AUT".

The functions4
14 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
4.2 Setting the room temperature
The rotary selector can always be used to adjust the room
temperature. The room temperature can be adjusted in three
ways:
– Change the room temperature for the current operating mode
(e.g. automatic day mode). The changed setting applies to
automatic day mode from now on.
– Change the room temperature temporarily. The changed
setting is retained until the heating system changes the
operating mode (e.g. to night mode).
– Change the room temperature for another operating mode
(e.g. change the night room temperature during the day). The
changed setting will apply to this operating mode from now on.
4.2.1 Setting the room temperature for the current
operating mode
The set room temperature applies to the currently active heating
mode, i.e. day or night mode. The currently active heating mode is
indicated by the relevant symbols.
You are currently in automatic mode and would like to change the
room temperature.
Press the "AUT" key and select the required room temperature
using the rotary selector.
USER NOTE
The actual room temperature is shown as the standard display.
Your heating contractor can also set the controller to a different
standard display.
USER NOTE
The room temperature sensor is in the RC20. It is not possible to
connect a separate external room temperature sensor.
+

The functions 4
15
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Operating instructions RC20 room controller • Issue 08/2006
The display changes from the standard display to the set room
temperature, which you can now alter (e.g. here for automatic day
mode). Turning the rotary selector clockwise increases the value,
turning anti-clockwise reduces the value.
The newly selected room temperature will be saved after
approx. 2 seconds. The display then returns to the standard
display (e.g. actual room temperature).
4.2.2 Changing the room temperature temporarily
(temporary room setting)
You are currently in automatic mode or in manual mode and would
like to change the room temperature temporarily. This function is
available when the RC20 is the sole programming unit or it has
been installed as a remote control unit for an RC35 programming
unit (see section 5.1, page 23). If the RC20 has been installed as
a remote control unit for an RC30 programming unit, use manual
mode (see section 4.1.3, page 13).
Set the required room temperature by turning the rotary selector.
The display changes from the standard display to the set
room temperature, which you can now alter. Turning the rotary
selector clockwise increases the value, turning anti-clockwise
reduces the value.
The newly selected room temperature will be saved after
approx. 2 seconds. The display then returns to the standard
display (e.g. actual room temperature).
USER NOTE
If holiday mode is active for a heating circuit when using an RC35
(RC20 as remote control), the holiday setting can be adjusted on
the RC20, but not the temporary room setting.

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16 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
4.2.3 Setting the room temperature for an operating mode
that is currently inactive
You can also adjust the room temperature for an operating mode
that is currently inactive.
For example, you are currently in automatic "Day" mode and would
like to alter the night setback temperature.
Hold down "Night mode" and select the required room temperature
with the rotary selector.
The display changes from the standard display to the set night
temperature, which you can now alter.
Release the "Night mode" key. The newly selected night
temperature will be saved after approx. 2 seconds. The display
then reverts to the standard display.
Press "AUT".
The LED in the "AUT" key lights up; automatic mode is active
again.
USER NOTE
The symbol indicates that this is a temporary room setting.
The temporarily changed temperature setting is retained until you
press one of the operating mode keys (e.g. "AUT" key) or until the
heating system changes the operating mode (e.g. to night mode).
+
USER NOTE
If you are currently in automatic "Night mode", and you wish to
adjust the set day temperature, proceed as described above, but
instead hold down the "Day mode" key.

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Operating instructions RC20 room controller • Issue 08/2006
4.3 Heating domestic hot water
The programming unit also offers you the option of heating DHW
in an energy-conscious manner. Adjustment depends on how the
room controller was installed (see section 5.1 "What does the
RC20 room controller regulate?", page 23):
– If the RC20 room controller is the only programming unit in the
system, DHW heating commences automatically 30 minutes
before the heating program starts its day mode. DHW is not
produced during might mode. In day mode, the DHW
circulation pump is started twice every hour for three minutes
to ensure a constant supply of hot water to taps. The DHW
temperature can be set to a maximum of 60 °C
(= factory setting).
– If the RC20 room controller is installed as a remote control unit
for one heating circuit 1), DHW heating and the operation of the
DHW circulation pump for the entire heating system is adjusted
using the programming unit (e.g. RC30/RC35). The selected
DHW temperature can be modified using the RC30/RC35 or
the RC20; however, the setting range of the RC30/RC35
applies (max. 80 °C).
4.3.1 Setting the DHW temperature
You can check or change the DHW temperature:
Hold the DHW key down and select the required DHW temperature
using the rotary selector.
WARNING!
RISK OF SCALDING
The factory-set DHW temperature is 60 °C. There is a risk of
scalding at the taps if the temperature is set to above 60 °C.
zIf the DHW temperature is set to above 60 °C, you should only
draw off mixed hot and cold water.
+
1) Not possible for operation using boilers with UBA 1.x.

The functions4
18 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
Release the "DHW" key. The new DHW temperature setting is
saved immediately. Then the standard display is shown again.
4.3.2 Single charge – domestic hot water 1)
In day mode, DHW is recharged subject to demand if the DHW
temperature falls 5 °C below the set value.
In night mode, any hot water can still be drawn from the DHW
cylinder. The DHW temperature will have fallen below the set value
if the green LED on the "DHW" key is illuminated. Should you
require DHW at the selected DHW temperature once, proceed as
follows:
Press "DHW".
The LED of the "DHW" key illuminates, and the "Single DHW
charging" commences (up to the selected temperature).
Depending on the size of the DHW cylinder and the boiler rating,
the DHW will be available after approx. 10 to 30 minutes. With
instantaneous water heaters or combination boilers, DHW is
available almost immediately.
USER NOTE
If you have started this function in error, press "DHW" again.
Recharging will then be terminated and the LED stops flashing.
USER NOTE
In a modern Buderus DHW cylinder, the water only cools down at
a rate of around 0.5 °C per hour when not being drawn, i.e.
recharging only occurs after 10 hours. If necessary you can
manually recharge the DHW to 60 °C (see section 4.3.2 "Single
charge – domestic hot water 1)", page 18).
1) Not possible for operation using boilers with UBA 1.x.

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19
We reserve the right to make any changes due to technical modifications.
Operating instructions RC20 room controller • Issue 08/2006
4.4 Setting day and time
In order to function correctly, the correct day and time must be set
on your heating system. Both can be selected on the room
controller, for example after an extended power failure.
Day and time can only be selected on the RC30/RC35 if the RC20
room controller is allocated to a RC30/RC35 as remote control
unit. The RC30/RC35 then assumes the setting on the RC20.
zOpen flap.
Release the "Time" key to store the time.
Release the "Time" key to store the day.
Hold down "Time" and select the current time using the
rotary selector.
+
Hold down "Time" again, and select the current day using the
rotary selector (1 = Mo, 2 = Tu,... 7 = Su).
+
USER NOTE
Even after a power failure, the clock continues to run for
approx. 10 hours, as long as the room controller was supplied
with power for at least six hours before the failure.
If the clock constantly loses or gains time, ask your heating
contractor to make the necessary adjustments.

The functions4
20 Operating instructions RC20 room controller • Issue 08/2006
We reserve the right to make any changes due to technical modifications.
4.5 What is a heating program?
A heating program controls the automatic changeover of operating
modes (day and night mode) at fixed times. The heating program
also determines the times for DHW heating and the operation of
the circulation pump.
Before you select a heating program, consider the following:
– At what time in the morning do you want your home to be
warm? Does this time also depend on the day of the week?
– From what time in the evenings do you no longer need
heating? This too may depend on the day of the week.
The RC20 room controller from Buderus offers eight preset
standard programs that can be selected straightaway.
If the room controller has been installed as a remote control unit for
an RC30/RC35 programming unit, heating programs from the
RC30/RC35 can be used in the RC20 ("Own program",
see section 4.7 "Heating program summary", page 22).
USER NOTE
The time taken for your heating system to heat up individual
rooms may vary. This will be subject to the outside temperature,
the building insulation and the drop in room temperature.