Assortment / System Description

Central applications
Automation station for HVAC supply and demand signals and manual control for lighting and blinds
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On the DXR2. a threshold can be defined for the minimum number of collected
air demand messages from the rooms. The air demand to air supply is only
enabled if the minimum number of air demand messages is reached. The
threshold and hysteresis can be configured.
Description Name Default value
Number of minimum air demand plant mode AirDmdMin 4
Hysteresis for number of minimum air demand plant
mode
HysAirDmdMin 2
Central air handling is designed for heating and cooling. The consumers in the
rooms decided whether warm or cool air is to be supplied.
Heat and refrigeration demand is determined from the rooms, evaluated, and
decided, depending on the number, whether heating or cooling must be
transmitted to air handling. This occurs using a lower (heating) and upper
(cooling) supply air temperature setpoint to which the central air handling unit
is controlled. As illustrate in the following graph, demand (0...100 %) is
determined via the grouping functions for higher supply-air temperature for
heating and demand (0…100 %) for lower supply air temperature for cooling.
The control setpoints for supply air temperature control in the air handling unit
is derived from this.
The changeover condition air reports whether the supply air can be used from
the air handling unit for heating or cooling to the individual rooms. The
following operating modes are supported:
● Changeover condition (ChovrCndAir) = Heating.
● Changeover condition (ChovrCndAir) = Cooling.
● Changeover condition (ChovrCndAir) = Neither.
● Changeover condition (ChovrCndAir) = Neutral.
YH Heating valve positions YC Cooling valve positions
Changeover condition heating
The supply air setpoint for heating resides, as depicted in the diagram, on the
left side, and is determined dependent on demand 0...100% accordingly.
Conclusion for the room: The air is warm so that the air volume can be
increased for heating.
Changeover condition cooling
The supply air setpoint resides, as depicted in the diagram, on the right side,
and is determined dependent on demand 0...100% accordingly. Derived for the
room: The air is cold so that the air volume can be increased for cooling.
Enable supply air supply
Select supply air
temperature