Honeywell AUTOMATIC CONTROL User Manual

ENGINEERING CMANUAL OF AUTOMATION CONTROL
AIR HANDLING SYSTEM CONTROL APPLICATIONS
222
ECONOMIZER CYCLE CONTROL OF SPACE TEMPERATURE WITH SUPPLY AIR
TEMPERATURE SETPOINT RESET
Functional Description
OA
22
ECONOMIZER DECISION.
REFER TO PREVIOUS
ECONOMIZER OPTIONS
OA MINIMUM SETPOINT
(NOTE: THE TEST AND BALANCE INITIAL VALUE
FOR PROPER VENTILATION IS 22)
M10457
12
14
11
CONTROL
PROGRAM
83
EA
SAMA
RA
ON
ON
59
5
1
4
2
13
8
3
7
10
9
6
83
59
NORMAL
75
55
MIXED AIR
TEMPERATURE
RESET SCHEDULE
SPACE
TEMPERATURE
SUPPLY AIR
TEMPERATURE
SETPOINT
SPACE
COOLING
DEMAND
0
100
74
74
Item
No. Function
1-3 Control system energizes when fan is turned
on (See FAN SYSTEM START-STOP
CONTROL).
4 SA temperature maintained by modulating
mixing dampers.
5,6 OA and EA dampers close and RA damper
opens when fan is off and modulate for
ventilation and temperature control when fan
is on.
7 Setpoint for SA temperature control.
8 Space temperature demand resets SA
temperature setpoint.
9,10 Calculates SA temperature setpoint (7) based
upon space temperature cooling demand.
11 Setpoint value for minimum ventilation
damper position.
12 Determines when OA is suitable to assist in
cooling.
13 Space temperature setpoint and PID function.
PID output (0 - 100) inputs to reset schedule.
14 Control program coordinates space
temperature, SA temperature, minimum
ventilation, fan interlock, and economizer
control of mixing dampers.
FEATURES
1. The system admits only the minimum quantity of OA
required for ventilation when the OA is unsuitable for
cooling assistance.
2. During intermediate weather the system admits OA for
cooling to satisfy the space temperature demands, subject
to SA temperature schedule setpoints.
3. A minimum quantity of OA, determined by the software
adjustable setpoint value, is assured at all times.
CONDITIONS FOR SUCCESSFUL OPERATION
1. Adequate mixing of OA and RA. Mixing may be obtained
using a special mixing chamber. The temperature sensor
should be in the fan discharge when possible. The fan in
a blow-through system usually provides adequate mixing.
2. A satisfactory schedule of all settings must be determined.
LIMITATIONS
If the manual positioning value is set to admit a large quantity
of OA and the OA temperature falls below the temperature at
which only minimum OA is required for SA temperature
control, a source of heat is necessary to maintain the SA
temperature.

Honeywell AUTOMATIC CONTROL Specifications

General

Brand	Honeywell
Model	AUTOMATIC CONTROL
Category	Controller
Language	English