Microprocessor Controller for DOAS
25
Menu
s
upply
F
an
d
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
upply
F
an
s
peed
This screen displays min and max supply fan speed percentages.
The speed set
point is the proportional percentage of the analog output from the controller to the
VFD.
50% Speed = Min speed
100% Speed = Max speed
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).
Duct Pressure
– Fan speed is determined by duct pressure control loop.
Space Pressure
– Fan speed is determined by building pressure control loop.
CO
2
– Fan speed is determined by CO
2
control loop.
Single Zone VAV
- The supply fan is modulated in addition to the supply air
temperature to satisfy the space temperature set point.
2-Speed (High Speed Set Point)
- Supply fan speed is reset to max speed when
a contact closure is made. (Max Ventilation Mode).
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
oFT
s
huTdown
e
nable
c
ondiTions
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 set point
minus 5ºF; or
- The soft shutdown delay timer has expired.
Control Variables
Fan Control
Supply Fan Control
The
Supply Fan Control
menu allows the user to adjust exhaust control set
points
