Vav Ahu With Return Fan And Flow Tracking Control - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

AIR HANDLING SYSTEM CONTROL APPLICATIONS

VAV AHU WITH RETURN FAN AND FLOW TRACKING CONTROL

Functional Description
EA
83
20
22
17
21
83
OA
16
9
0.060
0.060
17
ECONOMIZER DECISION.
REFER TO PREVIOUS
ECONOMIZER OPTIONS
Item
No. Function
1-5 Control system energizes when supply fan is
turned on (See FAN SYSTEM START-STOP
CONTROL).
6-8 Supply fan loads to maintain duct static
pressure at the end of the longest run.
9-14 Return fan loads to track supply airflow minus
exhaust airflow minus air for pressurization.
15 Manual positioning value determines
minimum summer ventilation mixing damper
position. This position is fixed for the OA and
24.5
30
RA
ON 58 4.530
9
PERCENT
4
10
LOAD
18
14.5
NORMAL
00
23
26
25
24
76
CONTROL
PROGRAM
22
15
OA MINIMUM SETPOINT
(NOTE: THE TEST AND BALANCE INITIAL
VALUE FOR PROPER VENTILATION IS 22)
EXHAUST
EXHAUST
FAN "ON"
FAN
DIFFERENTIAL
ON
13
5
1
2
NORMAL
ON
63
PERCENT
LOAD
6
32
WARM-UP
MODE
ON OFF
29
32 13
28
relief air dampers; but is a minimum position
for the return air damper, the value of which
will be overriden to maintain a constant mixing
box negative static pressure and thus a constant
OA airflow.
16 OA determines SA temperature setpoint.
17 Economizer enables free cooling when OA
is suitable.
18 Mixed air temperature is for operator
information.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
258
ZERO
CALIBRATION
360
14
SPACE
3
m /s
PRESSURIZATION
1.274
DIFFERENTIAL
3
m /s
0.613
12
CONTROL
PROGRAM
31
11
3
3
m /s
6.423
SA
7
27
13
8
0.45
SA
OA
TEMPERATURE
TEMPERATURE
SETPOINT
13 4
16.5 -21
0.45
19
M15182