The DXR2 fan coil applications can automatically control modulating fans (DC 0…10 V). In addition, the fan can be enabled or locked with a potential free relay contact.
Sequences
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Y | Output signal |
| TR | Room temperature |
SpH | Effective heating setpoint |
| SpC | Effective cooling setpoint |
YH | Heating valve |
| YC | Cooling valve |
Q | Fan signal |
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Figure: Modulating fan sequence
Outputs
Analog outputs on the DXR2 control modulating fans.
Switch-off delay
The fan switch-off 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 for hold signal for air volume flow heating | DlyOffAflHldH | 30 [s] |
Return air sensor
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 air 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
Locking is a binary signal to protect fan coil equipment. The application locks the electric heating coils if no air flow is available or enables if available.