Space Control Of Heating, Economizer (Free Cooling), And Humidification; Heating System Control Process - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

AIR HANDLING SYSTEM CONTROL APPLICATIONS

HEATING SYSTEM CONTROL PROCESS

SPACE CONTROL OF HEATING, ECONOMIZER (FREE COOLING), AND HUMIDIFICATION

Functional Description
SPACE
OA
83
17
ECONOMIZER DECISION.
REFER TO PREVIOUS
ECONOMIZER OPTIONS
18
Item
No. Function
1,2 Control system energizes when fan is turned
on (See FAN SYSTEM START-STOP
CONTROL).
3-5 Space humidity PI loop controls humidifier
valve if space humidity falls to setpoint.
6,7 SA humidity high limit PI loop throttles
humidifier valve if duct humidity rises above
setpoint.
8 Control program coordinates space and
humidifier leaving air humidity control and
fan interlock.
9-11 Space temperature heating PI loop inputs to
SA temperature heating reset schedule.
12 SA temperature PI loop inputs to heating and
mixed air control programs.
4
45
3
52
7
CONTROL
PROGRAM
6
8
NC
5
RA
28
N.O.
N.C.
NORMAL
00
13
CONTROL
PROGRAM
20
OA MINIMUM SETPOINT
(NOTE: THE TEST AND BALANCE INITIAL
88
SA
52
13
12
1
ON
2
14
CONTROL
PROGRAM
22
19
VALUE FOR PROPER VENTILATION IS 22)
13 Hot water valve modulates to maintain SA
temperature setpoint.
14 Control program coordinates space and SA
heating control and fan interlock.
15,16 Space temperature cooling PI loop inputs to SA
temperature cooling reset schedule.
17 Mixing dampers modulate to maintain SA
temperature setpoint.
18 Economizer decision program determines when
OA is suitable to assist with cooling demand.
19 Mixing dampers minimum ventilation value.
20 Control program coordinates space and supply
cooling control, ventilation control, and fan
interlock.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
246
15
COOL
25
23.5
9
22
HEAT
10
SUPPLY AIR SPACE
TEMPERATURE HEATING
SETPOINT DEMAND
100
41
0
13
11
SUPPLY AIR SPACE
TEMPERATURE COOLING
SETPOINT DEMAND
100
13
0
27
16
M15175