York J Series - Time Clock; Scheduling; Fig. 16 - Exhaust Proportional Band; Fig. 17 - Exhaust Fan Control, Proportional Option

JOHNSON CONTROLS
34
FORM 100.50-NOM7 (808)
Unit Sequence of Operation
For this option to operate the Economizer Installed
setting must be selected ON and the Supply Fan must
be ON. If, during operation, the Economizer setting is
selected OFF, or the Supply Fan turns OFF, the exhaust
fan, if ON, will be shut down.
Proportional Control Based on Building
Pressure
Proportional control based on building pressure controls
the 0-10V proportional Exhaust Analog Output (EAO)
based on the pressure within the building or space. The
exhaust fan output will be controlled on or o based on
the position of the EAO.
When the controller is congured for this type of exhaust
system, the controller will monitor the building pressure
and modulate the 0-10V EAO based on the pressure. The
0-10V output will be direct acting (increasing pressure
will correspond to an increasing voltage output). The
output will be controlled by an appropriate closed loop
control algorithm with the Building Pressure Setpoint
used as the control point. The proportional band to be
used will be from the Building Pressure Setpoint mi-
nus the Exhaust Control Oset to the Building Pressure
Setpoint plus the Exhaust Control Oset. The algorithm
will be tuned for a full closed to a full open response
time of two minutes. The following gure illustrates the
proportional band for this control loop.
For the exhaust fan output, the controller will moni-
tor the EAO. When the EAO reaches or exceeds EAO
Position for the Exhaust Fan to Turn ON setpoint, the
controller will energize the Exhaust Fan Output. The
Exhaust Fan Output will remain energized until the
proportional exhaust output drops to or below EAO
Position for the Exhaust Fan to Turn OFF setpoint.
The following gure illustrates the control of the exhaust
fan for this control sequence.
FIG. 16 – EXHAUST PROPORTIONAL BAND
100%
Exhaust
Control Loop
Output
0%
minus Exhaust
Control Offset
plus Exhaust
Control Offset
Bldng. Press.
Setpoint
Building Pressure
LD06579A
FIG. 17 – EXHAUST FAN CONTROL,
PROPORTIONAL OPTION
ON
OFF
Exhaust Fan
O utput
OAD Position
for EF to Turn
OFF
OAD Position
for EF to Turn
Off
Exhaust Fan
Turns Off
Exhaust Fa
n
Turns On
0%
100%
LD06580
For this option to operate the Economizer Installed
setting must be selected ON and the Supply Fan must
be ON. If, during operation, the Economizer setting
is selected OFF, or the Supply Fan turns OFF, the pro-
portional exhaust output will be driven to 0V and the
exhaust fan, if ON, will be shut down.
Note, the Building Pressure will be obtained via input
from a dierential pressure transducer. The input will
be ltered, using an appropriate method, to compensate
for sudden pressure changes, such as wind gusts, doors
opening, etc.
TIME CLOCK / SCHEDULING
The controller will have a time of day clock and calendar
with the following characteristics:
• Battery backup
• Time and date set through the RDU
• Clock and calendar compensated for Leap Year and
Daylight Savings Time
• Event specication as follows:
• Up to 16 holidays
• A holiday schedule
• A daily start and stop time (two times)
• Capability to set up multiple scheduling functions
(i.e. time of day start-stop; time of day purge)
• Nominally +/- 4 seconds/day clock accuracy