Microprocessor Controller for DOAS
26
e
xhausT
F
an
d
elay
and
e
nable
This screen displays min and max exhaust fan speed percentages.
This screen
displays the exhaust fan delay and enable based on OA damper position. The
exhaust fan delay will begin once the damper sequence is complete. This delay
can be used to offset starting times between the supply fan and exhaust fan. This
screen also provides the ability to enable the exhaust fan on a set OA damper
position if the unit is equipped with a modulating OA damper.
e
xhausT
F
an
s
peed
p
ercenTages
The speed set point is the proportional percentage of the analog output from the
controller to the VFD.
25% Speed = Min speed
100% Speed = Max speed
Control Variables
Fan Control
Exhaust Fan Control
The
Exhaust Fan Control
menu allows the user to adjust exhaust control set
points.
Menu
Set Point Selections:
Constant Volume
–
The fan speed will be constant; set from screen (e.g. 100%).
BMS
–
The BMS can directly control the fan speed (requires BMS communication
option).
Space Pressure
–
Fan speed is determined by building pressure control loop.
Supply Fan Tracking with Offset
–
The exhaust fan will track the supply fan,
between a min and max position. An offset can be added to achieve the proper
balance.
Outside Air Damper Tracking
–
The exhaust fan will proportionally track the OA
damper, between a min and max position.
Return Duct Static Pressure
–
Fan speed is determined by duct pressure control
loop.
0-10V By Others
- The 0-10V signal directly correlates to the fan speed of
0-100%. When the signal is below the minimum fan speed setpoint, the fan will
operate at minimum. When the signal is above the maximum fan speed setpoint,
the fan will operate at maximum.
