Assortment / System Description

Room pressurization and fume hood control
Pressurized room, temperature control
21
A6V10866237_en--_b_08 201 | 275
Type of airflow Normal use Other possible use
Comfort
ventilation
(RVntMinCmf)
RVntMinCmf represents the ventilation rate for the room, not a specific
terminal. It may be set to comply with building codes that specify the rate
expected / needed when occupants are present (Comfort mode).
Might be set according to industry
standards for contamination control,
or to a client’s institutional
standards.
Pre-Comfort
ventilation
(RVntMinCmf)
The ventilation rate for rooms during a brief or scheduled occupancy
absence. If no such state is specified, configure same as Comfort.
--
Economy
ventilation
(RVntMinEco)
The room ventilation rate during typically unoccupied periods, such as
overnight. Can be zero for many kinds of spaces.
(May be specified as an “unoccupied ventilation rate” for laboratories.)
--
Protection
ventilation
(RVntMinPrt)
The ventilation rate for rooms with a defined operation for long-term
vacancy. For example, between semesters at a university. If no such state
is specified, configure same as Economy.
--
21.7.4.1 External volume flow control
A differential pressure sensor is typically connected to the VAV actuator for an
application with external volume flow control which, in turn also implements
volume flow control. In this case, the application in the DXR2 controls only the
room temperature and forwards the setpoint for volume flow control to the VAV
actuator.
The present damper position is determined in all cases by DXR2 and provided
to the central function for optimizing the supply air fan.
21.7.4.2 Internal volume flow control
A differential pressure sensor is typically connected to the DXR2 for an
application with internal volume flow control. It may be the Airflow Pressure
Sensor on the SCOM bus, or another type of air flow sensor. DXR2 then
controls volume flow in addition to temperature.
The present damper position is determined in all cases by DXR2 and provided
to the central function for optimizing the supply air fan.
21.7.5 Parallel supply air VAV or extract air VAV
A maximum of one room can be configured on each DXR2. The room can
consist of a maximum of one supply air and extract air VAV. You must create a
multisegment application with multiple DXR2 automation stations if you need
to use multiple VAV for supply or extract air. Any combination of supply air and
extract air VAV can be created with DXR2. The VAV can even have various sizes
and nominal air volume flows.
The standardized room control with controller signals 0…100% always controls
all connected VAV actuators for supply and extract air as per their nominal
volume flow and provides the correct amount of volume flow.
The DXR2.17CX controller can accommodate two segments on one controller.