Damper operation, Fan operation, Series fan – KMC Controls BAC-8007 Installation Guide User Manual
Page 65
Damper operation
Damper movement is determined by comparing the actual airflow reading to
the airflow setpoints. If the actual airflow is within 5% of the setpoint, no
damper action is initiated. Once within the 5% deadband, the actual airflow
must be outside a 7% deadband before damper position changes.
Fan operation
The SimplyVAV controllers support both series and parallel fan powered
VAV units. For either type of fan operation, the fan is controlled through the
following terminals.
A binary output triac controls a 24-volt fan starting circuit. See the topic
Configuring the VAV Box options
for the procedure to
configure the controller for a fan.
A 0-10 volt DC analog output controls the speed of the fan. The output
controls fan speed at either Min Fan Speed or Max Fan Speed. See the
topic
for the procedure to set the fan
speeds.
If the VAV unit is not configured for a fan, the two outputs are not used and
remain inactive regardless of the occupancy state.
Series Fan
If the controller is configured for a series fan, any time the Occupancy mode
of the controller is set to either
Occupied
or
Standby
, the fan runs
continuously. The fan speed is set to Maximum Fan Speed when the state is
Occupied
and set to Minimum Fan Speed when the state is
Standby
.
When the Occupancy state is
Unoccupied
, the fan starts and runs at minimum
speed only on a call for heating. The fan starts when the Heating loop is
greater than 5% and stops when the Heating loop is less than 1%.
Illustration 7–2 Series fan operation
UNOCCUPIED/
STANDBY
STANDBY
MAX FAN SPEED
MIN FAN SPEED
FAN OFF
OCCUPIED
HTG SP
ROOM TEMP INCREASE
SimplyVAV
Section 7: Sequences of operation
Revision E
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