Siemens RDF110 Manual page 5

External sensor input B1-M
Automatic heating /
cooling changeover
Remote heating /
cooling changeover
External room or
return air temperature
sensor
Summary
B1-M and P22
5/14
Siemens
Building Technologies
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
T Water temperature HM
w
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:
B1
M
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 Variables:
P22 The controller....
is in H/C mode
Heating only
controls according to
is in H/C mode
Cooling only
controls according to
Automatic
is in H/C mode
H/C
changeover
controls according to
Room Temperature Controllers
Cooling mode
Heating mode
Contact open  heating mode
B1
T
M
Contact closed  cooling mode
QAH11.1 3058Z03
No sensor at
B1-M
Heating
Internal sensor
Cooling
Internal sensor
Heating
Internal sensor
QAH11.1/QAA32 at
B1-M
Heating
Sensor at B1
Cooling
Sensor at B1
depending on the
temperature of sensor B1-
M
Internal sensor
N3057en
2014-10-28