3 Minute Read
The DAB terminal profile is a profile that controls the terminal equipment of a space, which is provided by an RTU or an AHU for its HVAC needs.
The profile is supported by a SmartNode, Smart Damper and a Smart Damper Actuator to provide the necessary control outputs based on the profile configured.
| How it Works
75F Dynamic Airflow Balancing operates to help temperature balance a system without fully closing off zones and creating harmful back pressure on the AHU.
Once you select the DAB terminal profile under SmartNode DAB profiles, the configuration provides the options to define the damper types, size, shape and zone priority. It also provides the options to define the minimum and maximum damper positions during heating and cooling along with the Temperature Offset.
Additionally, the profile provides options to modify the controls based on the Internal Air Quality and CO2, with the IAQ and CO2 control that can be enabled or disabled.
The Algorithm continuously track the current temperature of the zone and looks for the change in the difference between the terminal level Desired Temperature and Current Temperature and provide an optimal damper opening position within the deadband range, which is a resultant of the loop output based on the PI loop for control signals.
When the Current Temperature increases above the set point or desired temperature, the zone calls for cooling from the system or building level equipment.
And when the Current Temperature decreases below the set point or desired temperature, the zones call for Heating from the system or building level equipment.
The building or system level device is a RTU or AHU which is controlled by the system level DAB profiles.
For more information on the system level DAB profiles refer below.
Below is a wiring schematic for the DAB terminal profile, that show the connection between the SmartNode, Damper Actuator and the Damper.
A Temperature and Humidity only sensor, which can be a Wall Sensor/Ceiling Sensor/Duct Sensor/Flush Mount Sensor is connected to the RTS port of the SmartNode.
Points to be considered while wiring
When installing a belimo actuator, user 18gauge thermostat wire for connections between Smart Node and Actuator.
For the sensors, both ends of the harness are the same male connectors. Plug one end into the Wall Sensor. Plug the other end into the RTS port on the Smart Node.
Local Interface Option (Local Interface Sensor)
Below is the configuration screen for the DAB terminal profile.
Once you've paired the SmartNode as a DAB profile, and once a few specific configuration parameters that define the physical characteristics of the setup are set in the configuration screen, the 75F sequence for the DAB will influence and control the setup.
Damper 1 Type
Type of actuator being controlled on Damper port 1 or Analog out 1. 75F Smart Dampers are controlled using an MAT actuator through Damper port 1. If you are using a modulating 0-10Vdc type, then Damper 1 Type will be Analog Out 1 and will read TH1 for the DAT.
Damper 2 Type
Type of actuator being controlled on Damper port 2 or Analog out 2. 75F Smart Dampers are controlled using an MAT actuator through Damper port 2. If you are using a modulating 0-10Vdc type, then Damper 2 Type will be Analog Out 2 and will read TH2 for the DAT.
Size -Size of the associated damper. Used for calculating CFM.
Shape - Shape of the associated damper. Also used for calculating CFM.
Zone Priority -Used in calculations for driving the AHU into heating or cooling. (Low = 1, Normal = 10, High = 50)
Enable IAQ Control -Must have an IAQ sensor present. Nonstandard option.
Enable CO2 Control - Must have a CO2 sensor present. Nonstandard option.
Enable Occupancy Control - Must have an Occupancy Sensor present. Nonstandard option.
Temperature Offset -Value applied to the current temperature reading if the current temperature needs calibration. Sensors should not typically need calibration.
Min/ Max Damper Positions -Hard limits on damper positions in given mode.
Considering there are more than one terminal profile connected to the DAB system profile, when the zones are within the deadband the damper positions are managed using the terminal level loop output.
When the temperatures cross the deadband and zones call for cooling or heating from the system level equipment, the cooling or heating which the system level equipment provides is divided optimally for the zones, to help temperature balance a system without fully closing off zones and creating harmful back pressure on the AHU. This is achieved based on two approaches.
- Minimum overall Damper Position
Which is based on the DAB profile sequences and uses the aspects like the Zone priority, Damper size and other tuner parameters for the output calculations.