56
doMEStIc Hot wAtER (dHw),
RAdIAtoRS And two StAgE contRollER
two StAgE RooM tEMPERAtURE contRollER
11.0
11.3
Working Principle
REHAU CT2/2 provides two stage control of a designated area or
room which may be part of an underfloor heating system. These
units are used where a secondary heat source is employed to boost
the temperature within the area if the conventional heating system is
not powerful enough. For example, a conservatory, which features a
considerable glass area, can benefit by the switching of an additional
heat source i.e. electric radiators on very cold days when the normal
system cannot achieve the required temperature level.
A further application is where a heat pump is used to create the normal
system hot water, but on very cold days this may not be sufficient to
achieve the required temperature. The second stage can be used to
enable a back up boiler or immersion heater.
When a timed event occurs to raise the room temperature a function
within the controller allows the normal heating system to initially try to
achieve the temperature. If after a period of time (x) it has not warmed
the space to within (y) degrees of the required level, the second output
is enabled. Once the temperature has been achieved, the second
stage switches off, but if the temperature should then fall to below (y)
degrees of that required, the second stage is re-started after a similar
delay period. Within the advanced menu section of the controller, the ‘y’
setting can be adjusted by the client or installer from 0ºC to 10ºC,
and the ‘x’ setting can be adjusted from 0-2 hours, so an example
would be to bring on the 2nd stage if the temperature has not
reached within 2ºC (y) of the set point after (x) 30 minutes.
Programming
4 event time and temperature programming is similar to that of
standard CT2 Programmable Room Sensor. In addition it also
includes programming for second stage. An “optimum start” facility
(adaptive function) can also be enabled when the unit will calculate
the ON time, to achieve the required temperature by the start of the
programmed period. (Refer to section 10, on page 45)
Installation
The Two Stage Controller is installed as part of the BA
controller and set to a channel number, e.g. Channel 3. The
normal heating valve is connected to output 3. Output 4 on
the Master Controller becomes the second stage output,
and must not be used for any other function. The electrical
capacity of the output is 2 amps, so if electric elements are
being used, a relay or contractor should be employed.
THERMAL ACTUATORS 24V
L
N
L
L
L
L
L
N
N
N
N
N
Out put 1
L
N
L
L
L
L
L
N
N
N
N
N
THERMAL ACTUATORS 24V
L
L
N
N
L
L
N
N
SWITCH
EXT.
I
O
+
+
T
T
LINK
DISPLAY
L
Y
N
X
SUPPLY
SENSOR
SENSOR BUS
+
T
+
T
APP
SENSOR
SENSOR BUS
MIXING VALVE
0 - 10V
MIXING VALVE 24V AC
+
T
Out put 2 Out put 3 Out put 4 Out put 5 Out put 6 Out put 7 Out put 8
Out put 1 Out put 2 Out put 3 Out put 4 Out put 5 Out put 6 Out put 7 Out put 8
REHAU
CT2/ 2
T
T
+ +
REHAU CT2/ 2
Controller
Channel Selector
Set to '2'
ELECTRIC
HEATING
ELEMENTS
24 V RELAY
STAGE 1
STAGE 2
A1
A2
11
14
no
12
nc
24 V RELAY
A1
A2
11
14
no
12
nc
ZONE VALVE ON
RADIATOR CIRCUIT
L
N
EAR
TH
Master Controller
THERMAL ACTUATORS
1
2
3
4
5
6
L
N
L
L
L
L
L
N
N
N
N
N
1
2
3
4
5
6
L
N
L
L
L
L
L
N
N
N
N
N
THERMAL ACTUATORS
7
8
L
L
N
N
7
8
L
L
N
N
SWITCH
EXT.
I
O
+
+
T
T
DISPLAY
L
Y
N
X
SUPPLY
SENSOR
THERMOSTAT BUS
+
T
+
T
APP
SENSOR
THERMOSTAT BUS
MIXING VALVE
0 - 10V
MIXING VALVE 24V AC
+
T
ON
OFF
1 2 3 4 5 6 7 8
0
DIP SWITCH
NETWORK BUS
NETWORK BUS
ADD-ON
MODULE
WIRELESS
RECEIVER
RJ45
SUPPLY
230VAC
BOILER
B1
B2
230VAC
L
L
N
N
C1
C2
NOT USED
L
N
230V AC
Mains
Supply
Brown
Blue
Green/
Yellow
Orange
Grey
49. Wiring Schematic for REHAU CT2/2 Two STAGE Room Temperature Controller
Output for second stage control is always
adjacent to stage one control output