Microprocessor Controller for DOAS
25
®
T
HIS
SCREEN
DISPLAYS
THE
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.
T
HIS
SCREEN
DISPLAYS
M
INIMUM
AND
M
AXIMUM
S
UPPLY
F
AN
S
PEED
P
ERCENTAGES
.
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
Possible Setpoint Sources:
Local
– 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 room temperature set point. A room temperature
sensor is required.
2-Speed (High Speed Set Point)
- Supply fan speed is reset to maximum speed
when a contact closure is made. (Max Ventilation Mode).
T
HIS
SCREEN
DISPLAYS
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 setpoint
minus 5.0ºF; 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
setpoints
Menu
