The three selections for Box Fans provide the necessary State Generator, Output Controller, and Outputs based on the type of fan selected.
If an Exhaust Damper (Exhaust Damper Actuator (VAV-SD)) is selected, Box Fans cannot be selected.
-
Parallel Fan Single Speed provides airflow in parallel to the primary airflow in the box. The source for this air is normally from the return plenum. Parallel fans can be used to provide additional air volume during heating mode (Temperature Based), or to provide additional flow in low volume systems (Flow Based).
- Parallel Fan Variable Speed provides an analog output to control the speed of a parallel fan. In a Guideline 36 configured VAV application, the output varies during operation. In a non-Guideline 36 configured VAV application, the output is not varied during operation; it is designed to be set to a single speed during the Test and Balance phase.
-
Series Fan Single Speed draws return air into the VAV box when the primary airflow is less than the flow provided by the Series fan.
-
Series Fan Variable Speedprovides an analog output to control the speed of a series fan. The output is not varied during operation; it is designed to be set to a single speed during the Test and Balance phase. It does not control the fan at this speed while the box is operating. If you select this option, you may select Series Fan Enable to add a binary output to start the fan. Some fan speed controllers require this output.
-
Fan Status: This option creates a monitoring only point to use during commissioning or to map to the Supervisory system.