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Control Variables
Fan Control
Supply Fan Control
®
Menu
The Supply Fan Control menu allows the user to adjust supply control
setpoints.
s
F
d
upply
an
elay
The supply 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.
s
F
s
upply
an
peed
This screen displays min and max supply fan speed percentages. The speed
setpoint is the proportional percentage of the analog output from the controller to
the VFD.
50% Speed = Min speed
100% Speed = Max speed
Setpoint 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).
Duct Pressure – Fan speed is determined by duct pressure control loop.
Space Pressure – Fan speed is determined by building pressure control loop.
CO
– Fan speed is determined by CO
2
Single Zone VAV - The supply fan is modulated in addition to the supply air
temperature to satisfy the space temperature setpoint.
2-Speed - Supply fan control utilizes a contact closure to determine which speed
the supply fan speed is commanded; minimum or maximum. The "Max Vent"
contact closure maybe be field configured to temporarily force the unit into
occupied mode. Reference Ctrl Variables/Advanced/Advanced Setpoints/Max
Vent to enable this option.
0-10 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.
s
s
e
oFT
huTdown
nable
During a soft shutdown the following will occur:
• Tempering outputs immediately revert back to their off value; while
• Dampers remain open and fans continue to run; until
- The supply air temperature falls below the soft shutdown enable setpoint
minus 5ºF; or
- The soft shutdown delay (0 sec adj.) timer has expired.
control loop.
2
Microprocessor Controller for MUA
17
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