Assortment / System Description

Heat pump application
Heat pump control
20
170 | 275 A6V10866237_en--_b_08
The switch off of a fan is delayed for a specific period on applications that have
electric heating coils/reheaters. This cools down the electric heating
coils/reheater with circulating air. The switch-on/switch-off time can be
configured.
Description Name Default value
Switch-off delay holding signal for air volume flow
heating
DlyOffAflHldH 30 [s]
The fan must be switched on if room temperature measurement is made using
a return air sensor in the fan coil system, to correctly acquire the actual room
temperature. A minimum air volume is enabled in the dead zone by default for
the operating mode Comfort on the DXR2. The parameter cannot be changed
when using a return air sensor to measure room temperature.
In this case, note that a conventional room temperature sensor must be
configured at the DXR2 input. The return are temperature sensor is then
connected instead of the room temperature sensor. The room is now
temperature controlled per the measured value from the return air sensor.
DXR2 does not support interval-type fan activities to periodically measure room
temperature with the return air sensor.
Also note that DXR2 temperature control in the room can only have one
measured return (temperature sensor) which is always configured and
connected at the input of the room temperature sensor. The available
configuration for a return air sensor is used for visualization on DXR2.
Locking is a binary signal to protect heat pump equipment. The application
locks the electric heating coils if no air flow is available or enables if available.
20.5 Heat pump control
DXR2 heat pump applications heating, cool, or dehumidify room air. The main
outputs are analog or binary outputs to control the compressor, binary output to
switch the reversing valve, optional output to activate hot gas reheater, and an
optional binary output to enable the local source (e.g. water pump).
Heat pump availability is based on the outside temperature to avoid problems
with icing and refrigerant and be configured.
Description Name Default value
Enable heat pump lock at low outside temperature
0:No
1:Yes
EnLockHpuTOaLo 0:No
Lock heat pump at low outside temperature LockHpuTOaLo 4 [°C]
Outside temperature hysteresis to lock heat pump HysTOaLockHpu 1 [K]
Switch-off delay
Return air sensor
Locking
Outside temperature-
dependent setpoint
availability of the heat
pump