Basic Documentation

Functions
Additional functions
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4.5.1 Sensors and changeover functions
Heating/cooling changeover information is received via Modbus. This is possible
only when the control sequence is set to automatic heating/cooling changeover
(P01 = 3) and no local input (B1/X1/S1) is assigned to this function.
Required information is unavailable (e.g., due to data communication problems,
power failure, etc.), the thermostat operates in the last valid room operating mode
(heating or cooling).
If a cable temperature sensor (QAH11.1 + ARG86.3) is connected to B1/X1/X2 and
P38/P40 is set to 2, the water temperature acquired by the changeover sensor is
used to change over from heating to cooling, or vice versa.
● When the water temperature is above 28 °C (adjustable via P37), the
thermostat changes over to heating and remains there until the temperature
drops below 16 °C (adjustable via P36).
● When the water temperature is below 16 °C (P36), the thermostat changes
over to cooling and remains there until the temperature exceeds 28 °C (P37).
● If the water temperature is between the 2 changeover points immediately after
power-up (within hysteresis), the thermostat starts in the previous mode.
The water temperature is acquired at 30 s intervals and the operating state is
updated accordingly.
M
Operating mode
Cooling mode
T
w
Water temperature
Heating mode
The setting range is 10...25 °C for P36 and 27… 40 °C for P37.
The QAH11.1 cable temperature sensor for automatic heating / cooling
changeover can be replaced by an external switch for manual, remote changeover:
Contact open ⇨ Heating mode
Contact closed ⇨ cooling mode
The sensor or switch connects to input terminals B1/X1/X2, depending on input
commissioning (P38/P40).
See also Multifunctional input, digital input [➙ 43].
Heating/cooling
changeover via Modbus
(P01)
Heating/cooling
changeover
Automatic
heating/cooling
changeover via
changeover sensor (P36,
P37)
Note
Changeover switch
(P38/P40)