Vav Ahu With Return Fan And Flow Tracking Control - Honeywell AUTOMATIC CONTROL 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
49
-0.24
-0.24
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 airflow for
pressurization.
ENGINEERING CMANUAL OF AUTOMATION CONTROL
76
30
RA
ON 58 9600
9
PERCENT
4
10
LOAD
18
58
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
90 55
28
15 Manual positioning value determines
minimum summer ventilation mixing damper
position. This position is fixed for the OA and
relief air dampers; but is a minimum position
for the return air damper, the value of which
will be overridden 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.
258
ZERO
CALIBRATION
360
14
SPACE
CFM
PRESSURIZATION
2700
DIFFERENTIAL
CFM
1300
12
CONTROL
PROGRAM
31
11
3
13610
SA
7
27
55
8
1.8
SA
TEMPERATURE OA
TEMPERATURE
SETPOINT
55 40
61 -5
1.8
19
M10467