Siemens BACnet ATEC 125-5050 - Manual (Page 20)

Chapter 2 – Applications
20
Siemens Industry, Inc.
BACnet ATEC Owner's Manaul
125-5050, Rev. AA 4/20/2010
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Application 2865 VAV Series Fan Powered with Hot Water Reheat
In Application 2865, the controller modulates the supply air damper of the terminal box
for cooling and modulates a hot water valve for heating. When in heating, the terminal
box either maintains minimum airflow or modulates the supply air damper. Application
2865 has a series fan for air circulation. In order for the terminal box to work properly,
the central air-handling unit must provide supply air.
See the following figure.
Fan Operation
CAUTION
On series fan powered terminal boxes, the terminal box fan must be
controlled/interlocked to start either before or at the same time as the central air
handler. Failure to do so may cause the terminal box fan to rotate backwards and
cause consequent damage at start up.
In day mode, the fan is ON all the time. In night mode, the fan cycles on when heating
or cooling is required.
Application 2866 VAV Parallel Fan Powered with Electric Reheat
In Application 2866, the controller modulates the supply air damper of the terminal box
for cooling and controls stages of electric reheat for heating. When in heating, the
terminal box either maintains minimum airflow or modulates the supply air damper.
Application 2866 has a parallel fan that re-circulates the room air. In order for the
terminal box to work properly, the central air-handling unit must provide supply air.