FORM 100.50-NOM7 (808)
33
JOHNSON CONTROLS
3
Note, per this control sequence, both the Master and
Subordinate units must be configured exactly the
same for reliable operation. For example, if one unit is
equipped with an exhaust fan and the other is equipped
with just an On/Off exhaust fan, stable operation may
not be possible.
Lost Communications
If communications are lost between the Master unit
and the Subordinate unit, the Subordinate unit will shut
down (if operating) and will not be allowed to operate.
The Master unit can still operate, if necessary.
POWER EXHAUST OPERATION
Power Exhaust Operation is used to control building
pressure. For building pressure control, the unit can
be equipped with the following exhaust air control
configurations:
• Two position exhaust fan control based on the out-
side air damper position (1).
• Two position exhaust fan control based on the build-
ing pressure (2).
• Proportional exhaust fan control based on the build-
ing pressure (3).
• Proportional exhaust damper control based on the
building pressure (3).
For Power Exhaust Operation:
• The Power Exhaust Enable is programmed and the
supply fan must be running.
Two Position Control Based on OAD Position
Two position control based on OAD position controls
the powered exhaust fan ON or OFF based on the po-
sition of the Outside Air Damper. Two position operation
requires:
• Economizer = ON
• Constant Volume = ON
• Supply Fan = ON
This operation is not available when an OA Flow Sta-
tion is installed.
The Exhaust Fan will be controlled by the OAD position
as follows:
• Fan ON when the position = OAD Position for the
Exhaust Fan to Turn On.
• Fan OFF when the position = OAD Position for the
Exhaust Fan to Turn OFF.
• Fan OFF when Supply Fan = OFF.
and as illustrated in the following figure.
FIG. 14 – OAD POSITION CONTROL
Exhaust Fan
Turns Off
O AD Position
for EF t
o Turn
OFF
O N
OFF
O AD Position
Exhaust Fa
Turns On
O AD Position
for EF t
o Turn
O N
LD06577
Two Position Control Based on Building
Pressure
Two position control based on building pressure controls
the powered exhaust fan on or off based on the pressure
within the building or space.
When the controller is configured for this type of exhaust
system, the controller will monitor the building pres-
sure. When the building pressure reaches or exceeds
the
Building Pressure Setpoint
plus
the
Exhaust Control
Offset
, the controller will energize the Exhaust Fan BO.
The Exhaust Fan BO will remain energized until the
Building Pressure drops to or below the
Building Pres
-
sure
Setpoint
minus the
Exhaust Control Offset
. The
following figure illustrates this control sequence.
FIG. 15 – BUILDING PRESSURE CONTROL
ON
OFF
Building Pressure
Setpoint
minus Exhaust
Control Offset
plus Exhaust
Control Offset
Exhaust Fan
Turns Off
Exhaust Fan
Turns On
LD06578A
Summary of Contents for J Series
Page 85: ...FORM 100 50 NOM7 808 85 JOHNSON CONTROLS 6 ELECTRICAL NOTES AND LEGEND LD13862 ...
Page 87: ...FORM 100 50 NOM7 808 87 JOHNSON CONTROLS 6 LD13864 ...
Page 88: ...JOHNSON CONTROLS 88 FORM 100 50 NOM7 808 Service OPTI CONVERSION TO 25 40 TON LD13854 ...
Page 89: ...FORM 100 50 NOM7 808 89 JOHNSON CONTROLS 6 LD13865 ELEMENTARY DIAGRAM ALL UNITS ...
Page 91: ...FORM 100 50 NOM7 808 91 JOHNSON CONTROLS 6 ELEMENTARY DIAGRAM GAS HEAT 25 40 TON 575V LD13861 ...
