ABB FBVi-2U4-4T - Fan Control; Parallel Fan; Series Fan; Variable Speed Fan

FBVi-2U4-4T | Control Sequence
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Subject to change without notice
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93
MAN0148 rev 5
FAN CONTROL
PARALLEL FAN
The intermittent single speed fan will be energized when the FBVI-2U4-4T is in the heat mode. It will be
off when not in the heat mode.
MODE
COOLING
DEADBAND
HEATING
Occupied
Off
Off
On
Unoccupied
Off
Off
On
Warm-up
Off
Off
Off
Standby
Off
Off
On
SERIES FAN
The terminal unit fan will operate continuously whenever the FBVI-2U4-4T is in the occupied state. It
will also run whenever the FBVI-2U4-4T is in the unoccupied heating or unoccupied cooling mode. When
initially powered up, or upon restoration of power after a power outage, the FBVI-2U4-4T controller
executes a fan startup sequence to prevent reverse rotation. The fan startup sequence drives the
primary air damper closed, waits 60 seconds, and then sets the fan speed output.
MODE
COOLING
DEADBAND
HEATING
Occupied
On
On
On
Unoccupied
On
Off
On
Warm-up
N/A
On
On
Standby
On
On
On
VARIABLE SPEED FAN
The terminal unit fan speed will be controlled through AO-15 (0
…
10 V dc, or a custom range).
PARALLEL VARIABLE SPEED FAN
The Parallel Variable Speed fan will be energized when the FBVI-2U4-4T is in the heat mode and off when
not in the heat mode. Speed will modulate between the Minimum and Maximum Setpoints as detailed in
Section 3: Control Sequences.
SERIES VARIABLE SPEED FAN
When initially powered up, or upon restoration of power after a power outage, the FBVI-2U4-4T
controller executes a fan startup sequence to prevent reverse rotation. The fan startup sequence
drives the primary air damper closed, waits 60 seconds, and then sets the fan speed output.
The Series Variable Speed fan will operate continuously whenever the FBVI-2U4-4T is in the occupied
state. It will also run whenever the FBVI-2U4-4T is in the unoccupied heating or unoccupied cooling
modes. Speed will modulate between the Minimum and Maximum Setpoints as detailed in Section 3:
Control Sequen