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operation, the pressure within the building in monitored
by the OptiLogic™ controller. If the pressure rises to or
above a selected turn-on pressure, the Exhaust Fan is
cycled ON. The fan shall remain on as long as the pres-
sure within the building remains above a selected turn-
off pressure. If the building pressure falls to or below
the selected turn-off pressure, the Exhaust Fan is cycled
OFF. The turn-on and turn-off pressure setpoints are
user selectable from the OptiLogic™ User Interface.
Powered Variable Volume Exhaust-Discharge
Damper Controlled
This optional variable volume powered exhaust system
consists of a fixed speed fan configured with a propor-
tionally controlled discharge damper. The OptiLogic™
controller monitors the pressure inside the building and
controls the Exhaust Damper and the Exhaust Fan. If
the Building Pressure rises, the Exhaust Damper is pro-
portionally controlled open and the Exhaust Fan is con-
trolled ON. If the Building Pressure falls, the Exhaust
Damper is proportionally controlled closed and the Ex-
haust Fan is controlled OFF. The position of the Ex-
haust Damper in which the Exhaust Fan is controlled
ON and OFF as well as the Building Pressure setpoint
is user selectable from the OptiLogic™ User Interface.
Powered Variable Volume Exhaust-VFD
Controlled
This optional variable volume powered exhaust system
consist of an Exhaust Fan driven by a Variable Fre-
quency Drive (VFD), which is controlled by the
OptiLogic™ controller. The OptiLogic™ controller moni-
tors the pressure within the building. As the pressure
rises, the VFD is controlled to increase Exhaust Fan
speed. As the pressure falls, the VFD is controlled to
decrease Exhaust Fan speed. The Building Pressure
Setpoint is user selectable from the OptiLogic™ User
Interface.
LOW AMBIENT OPERATION
The OptiLogic™ controller continuously monitors the
outside air temperature to determine if mechanical cool-
ing should be allowed. As a safety, if the Outside Air
temperature falls to or below the Low Ambient Lockout
temperature, mechanical cooling is prevented from op-
erating. For units with economizers, the Low Ambient
Lockout temperature is typically low enough that me-
chanical cooling will rarely be required. However, for
some applications mechanical cooling is required when
the Outside Air temperature is lower than the Low Am-
bient Lockout temperature.
For these applications, the unit can be equipped with
optional Low Ambient controls. For optional Low Ambi-
ent operation, the OptiLogic™ controller monitors the
refrigeration system discharge pressure and controls
the speed of the condenser fans. If the discharge pres-
sure falls, the speeds of the condenser fans are re-
duced to maintain acceptable condensing pressures in
the refrigeration system. With the optional Low Ambi-
ent controls, mechanical cooling is allowed down to
Outside Air temperatures of 0°F.
SMOKE PURGE SEQUENCES
General
As a convenience, for when buildings catch fire or the
building is inundated with smoke or fumes from manu-
facturing processes, etc., the OptiLogic™ control sys-
tem provides one of five ventilation override control se-
quences for building purge. The five selectable purge
sequences are, Shutdown, Pressurization, Exhaust,
Purge and Purge with duct pressure control. Note, when
any of the purge sequences are activated, cooling and
heating modes are disabled. A contact closure is pro-
vided which indexes the OptiLogic™ controller into the
selected purge sequence.
Shutdown
When this purge sequence is selected and activated,
the supply and exhaust fans are controlled OFF and
the Outside Air damper is overridden closed. This idle
state is maintained until the purge input is deactivated
and the unit returns to normal operation.
Pressurization
When this purge sequence is selected and activated,
the exhaust fan is controlled OFF and the Supply Fan
is controlled ON. The Outside Air damper is opened
full and the Return Air Damper is closed full. If the unit
is a VAV unit, the VAV boxes are also driven full open to
prevent duct over-pressurization. This mode is main-
tained until the smoke purge input is deactivated and
the unit returns to normal operation.
Exhaust
When this purge sequence is selected and activated,
the Supply Fan is controlled OFF and the Exhaust Fan
is controlled ON (Exhaust Damper driven full open).
This mode is maintained until the smoke purge input is
deactivated and the unit returns to normal operation.
Controls
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