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External/return air
temperature sensor
Minimum output
ON-time/OFF-time
Floor temperature
limitation function
External temp.
P51
sensor available
OFF
No
OFF
Yes
10...50 ˚C
No
10...50 ˚C
Yes
Fault state
Fault information
Siemens
Smart Infrastructure
3.5
Additional functions
The thermostat acquires the room temperature through its built-in sensor, external
room temperature sensor (QAA32), or external return air temperature sensor
(QAH11.1) connected to multifunctional input X1 or X2. Input X1 or X2 must be
configured accordingly. See section 3.9.
Limit the On/Off switching cycle to protect the HVAC equipment (e.g. a
compressor) and to reduce wear and tear. The minimum output ON-time and OFF-
time for 2-position control output can be adjusted from 1 to 20 minutes using P48
and P49.
This function applies to UFH only and the factory setting is 1 minute.
Re-adjusting the setpoint or heating/cooling mode changeover immediately results
in calculation of the output state; the outputs may not hold the minimum 1-minute
On/Off time.
If P48 or P49 is set to above 1 minute, the minimum On/Off time for the control
output is maintained as set, even if the setpoint or changeover mode is readjusted.
The floor temperature should be limited for two reasons: Comfort and protection of
the floor.
The floor temperature sensor, connected to multifunctional input X1 or X2, acquires
the floor temperature. If it exceeds the parameterized limit (P51), the heating valve
is fully closed until the floor temperature drops to a level 2 K below the
parameterized limit.
Factory setting of this function is "OFF" (disabled).
Input X1 or X2 must be configured accordingly (P38 or P40 = 1).
See section 3.9.
The table below shows the relation between parameter, temperature source and
temperature display:
Source for display of
room temperature
Built-in sensor
External sensor
Built-in sensor
Built-in sensor
The alarm
icon flashes during temporary override and the fault "Condensation
in room" is sent using the bus.
The input must be configured accordingly (P38, P40). See section 3.9.
RDF880KN..
Basic documentation
Output control according to
Built-in sensor
External temp. sensor
Built-in sensor
Built-in sensor + limit by external
sensor
Floor temp.
limit function
Not active
Not active
Not active
Active
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A6V12318532_en--_a
2021-03-22
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