Zero Energy Band - Honeywell AUTOMATIC CONTROL Engineering Manual

CHILLED WATER TEMPERATURE SETPOINT CONTROL
AUTOMATIC MODE SEQUENCE OF CONTROL
ANYTIME ANY AHU CHW VALVE IS
TEMPERATURE SETPOINT WILL BE DECREMENTED
BUT TO NO LESS THAN
ANYTIME ALL AHU CHW VALVES ARE
CHW TEMPERATURE SETPOINT WILL BE INCREMENTED
DEGREES, BUT TO NO GREATER THAN
THIS PROGRAM EXECUTES EVERY
Load reset works best when the number of monitored loads
are between 2 and 30. If any monitored load is undersized or
stays in full cooling for any reason, reset will not occur. See
the Air Handling Systems Control Applications section and
the Chiller, Boiler, and Distribution System Control
Applications section for other load reset examples.

Zero Energy Band

The zero energy band (Fig. 11) program provides a dead
band where neither heating nor cooling energy is used. This
limits energy use by allowing the space temperature to float
between minimum and maximum values. It also controls the
mixed-air dampers to use available outdoor air if suitable for
cooling. On multizone fan systems with simultaneous heating
and cooling load capability, zone load reset controls the hot
and cold deck temperature setpoints.
MANUAL SETPOINT
46
AUTO-MANUAL SELECTOR
AUTO
CURRENT LEAVING WATER TEMPERATURE
45
36 CURRENT CHILLER LOAD (% AMPS)
95
DEGREES.
44
80
51
4.0
Fig. 10. Dynamic Data Display Example
MICROPROCESSOR-BASED/DDC FUNDAMENTALS
% OPEN, THE CHW
DEGREES,
0.3
% OPEN, THE
0.3
DEGREES.
MINUTES.
HEATING
REGION
FULL
ON
HEATING
FULL
OFF
70
TYPICAL SPACE TEMPERATURE RANGE (F)
Fig. 11. Zero Energy Band.
141
ENGINEERING MANUAL OF AUTOMATIC CONTROL
CURRENT VALUE
CHILLED WATER
VALVES
AHU %
# OPEN
1
68
2
73
3
74
4
77
5
79
6
70
7
64
8
69
9
79
10
74
11
74
12
74
TOTAL COMFORT RANGE
ZERO ENERGY COOLING
BAND REGION
VENTILATION
ONLY COOLING
75
73
M10358
78
C2431