External sensor input B1-M
With the RDF210, a return air / external room temperature sensor or heating / cooling
changeover sensor can be connected to terminal B1-M. The function of this sensor
input is determined by parameter P22.
Sensor input B1-M is not galvanically separated from the AC 230 V mains supply.
Therefore, only a cable temperature sensor and wiring with sufficient insulation must be
used.
When P22 is set to “Automatic H/C changeover”, the sensor input acts to ensure auto-
matic heating / cooling changeover. The water temperature acquired by the changeover
sensor (QAH11.1 + ARG86.3) is used to switch from heating to cooling mode, or vice
versa. When the water temperature lies above 28 °C (parameter P24), the controller
switches to heating mode; below 16 °C (parameter P23), it switches to cooling mode. If,
immediately after switching on, the water temperature lies between the 2 changeover
points, the controller will start in heating mode. The water temperature is acquired at
30-second intervals and the operating state is updated.
Automatic heating /
cooling changeover
Automatic H/C changeover
CM
HM
M
T
W
[°C]
30
21
D
03
16
28
M
Operating mode
CM
Cooling mode
T
w
Water temperature
HM
Heating mode
Remote heating /
cooling changeover
The QAH11.1 cable temperature sensor for automatic heating / cooling changeover can
be replaced by an external switch (suited for mains voltage) for manual remote change-
over:
3058Z03
B1
M
T
B1
M
QAH11.1
T °C
Contact open
Æ
heating mode
Contact closed
Æ
cooling mode
With parameter P99 (diagnostic value), automatic heating / cooling changeover can be
checked.
External room or
return air temperature
sensor
When parameter P22 is set to “Cooling only” or “Heating only”, sensor input B1-M can
be used to connect an external room temperature (QAA32) or a return air temperature
sensor (QAH11.1). Changeover is automatic if a sensor is detected at the sensor input.
With parameter P98 (diagnostic value), the sensor status can be checked.
Summary
B1-M and P22
The following table summarizes the relation between parameter P22, external sensor
B1-M and variables which the controller uses for maintaining the temperature:
Parameter
P22
Variables:
The controller….
No sensor at
B1-M
QAH11.1/QAA32 at
B1-M
is in H/C mode
Heating
Heating
Heating only
controls according
Internal sensor
Sensor at B1
is in H/C mode
Cooling
Cooling
Cooling only
controls according to
Internal sensor
Sensor at B1
is in H/C mode
Heating
depending on the tempera-
ture from sensor B1-M
Automatic
H/C change-
over
controls according to
Internal sensor
Internal sensor
7/15
Building Technologies
Room Temperature Controllers
N3058en
HVAC Products
10.01.2006
