ENGINEERING CMANUAL OF AUTOMATION CONTROL
AIR HANDLING SYSTEM CONTROL APPLICATIONS
255
VAV AHU, WATER-SIDE ECONOMIZER, OA AIRFLOW CONTROL
Functional Description
63
83
55
1.8
OA
RA
ON
ON
SUPPLY AIR
TEMPERATURE SETPOINT
MAXIMUM
SETPOINT
PROPELLER
EXHAUST
FAN
PERIMETER
ZONE
PERCENT
LOAD
SPACE
SA TO VAV
BOXES
WARM-UP
MODE
M10477
2
5
6
3
7
23
22
18
4
15
21
14
12
11
17
1
9
10
19
20
13
8
24
NORMAL
NORMAL
CFM
2300
90
ON OFF
CONTROL
PROGRAM
62 56
72
76
2306
16
00
1.8
77
75
WARM-UP MODE INVOLVED AT OPTIMUM
START TIME IF PERIMETER SPACE
TEMPERATURE IS LESS THAN
WARM-UP ENDS WHEN RETURN
AIR REACHES
70
74
.
.
ANYTIME ALL VAV BOX DAMPERS ARE LESS THAN 90% OPEN, DECREMENT THE AHU
DUCT STATIC PRESSURE SETPOINT INCHES EVERY MINUTES.
ANYTIME ANY VAV BOX DAMPER IS FULL OPEN, INCREMENT THE AHU DUCT STATIC
PRESSURE SETPOINT INCHES EVERY MINUTES.
0.1
0.1
4.0
4.0
1.8
Item
No. Function
1-3 Control system energizes when supply fan is
turned on (See FAN SYSTEM START-STOP
CONTROL).
4-6 Supply fan loads to maintain duct static
pressure.
7-10 During occupied periods, exhaust fan runs and
OA airflow is controlled.
11-14 When perimeter temperature is low at startup,
SA temperature setpoint is warm until RA
temperature rises.
15-16 Heating valve maintains SA temperature
setpoint during warm-up.
17-18 Cooling valve maintains SA temperature
setpoint during occupied periods.
19-20 OA and MA temperatures are operator
information.
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