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Siemens
Room Temperature Controllers
N3057en
Building Technologies
2014-10-28
External sensor input B1-M
With the RDF110, 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
automatic 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 H / C changeover
M
Operating mode
CM
Cooling mode
T
w
Water temperature
HM
Heating mode
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
changeover:
3058Z03
B1
M
T
B1
M
QAH11.1
Contact open
heating mode
Contact closed
cooling mode
With parameter P99 (diagnostic value), automatic heating / cooling changeover can be
checked.
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.
The following table summarizes the relation between parameter P22, the 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
Heating only
is in H/C mode
Heating
Heating
controls according to
Internal sensor
Sensor at B1
Cooling only
is in H/C mode
Cooling
Cooling
controls according to
Internal sensor
Sensor at B1
Automatic
H/C
changeover
is in H/C mode
Heating
depending on the
temperature of sensor B1-
M
controls according to
Internal sensor
Internal sensor
Automatic heating /
cooling changeover
Remote heating /
cooling changeover
External room or
return air temperature
sensor
Summary
B1-M and P22
