Power Exhaust Operation; Fig. 14 - Oad Position Control; Fig. 15 - Building Pressure Control - York J Series Manual

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
JOHNSON CONTROLS
Exhaust Fan to Turn OFF.
• Fan OFF when Supply Fan = OFF.
and as illustrated in the following figure.
Exhaust Fan
Tur ns Off
O N
OFF
O AD Posi t io n
O AD Posi t io n
f or EF t o Tu rn
OFF
FIG. 14 – OAD POSITION CONTROL
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.
Exhaust Fan
Tur ns Off
ON
OFF
Building Pressure
minus Exhaust
Control Offset
FIG. 15 – BUILDING PRESSURE CONTROL
FORM 100.50-NOM7 (808)
Exhaust Fa
Tur ns On
O AD Posi t io n
f or EF t o Tu rn
O N
LD06577
Exhaust Fan
Turns On
Setpoint
plus Exhaust
Control Offset
LD06578A
33
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