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292447-YIM-A-0507
Unitary Products Group 31
Power Exhaust
The Power Exhaust can be a factory installed option or a field
installed accessory. If factory installed, refer to the instructions
included with the outdoor air hood to complete the assembly.
Field installed Power Exhaust accessories include complete
instructions for installation.
The Power Exhaust factory installed option is for Down Flow
application only.
There are two field installed Power Exhaust accessories:
1. Down Flow application.
2. Horizontal Flow application that requires the purchase of a
barometric relief hood.
Rain Hood
All of the hood components, including the filters, the gasketing
and the hardware for assembling, are packaged and located
between the condenser coil section and the main unit cabinet, if
the unit has factory installed options. If field installed
accessories are being installed all parts necessary for the
installation comes in the accessory.
Economizer And Power Exhaust Set Point
Adjustments
Remove the top rear access panel from the unit. Locate the
economizer control module, where the following adjustments
will be made.
Minimum Position Adjustment
• Check that the damper blades move smoothly without
binding; carefully turn the Minimum Position Adjust screw
(found on the damper control module) fully clockwise and
then set the thermostat indoor fan switch to the ON
position and then OFF or energize and de-energize
terminals “R” to “G”.
• With the thermostat set to the indoor fan ON position or
terminals “R” to “G” energized, turn the Minimum Position
Adjusting screw (located on the damper control module)
counterclockwise until the desired minimum damper
position has been attained.
Enthalpy Set Point Adjustment
• The enthalpy set point may now be set by selecting the
desired set point shown in the Enthalpy Set Point
Adjustment Figure 26. Adjust as follows:
• For a single enthalpy operation carefully turn the set point
adjusting screw (found on the damper control module) to
the "A", "B", "C" or "D" setting corresponding to the lettered
curve of the Enthalpy Set Point Adjustment Figure 27.
• For a dual enthalpy operation, carefully turn the set point
adjusting screw fully clockwise past the "D" setting.
Power Exhaust Damper Set Point (With Or Without Power
Exhaust)
• With no power exhaust option, adjust the Exhaust Air
Adjustment Screw fully clockwise. This will allow 2nd
stage cooling to operate.
• With power exhaust option, each building pressurization
requirement will be different. The point at which the power
exhaust comes on is determined by the economizer
damper position (Percent Open). The Exhaust Air
Adjustment Screw should be set at the Percent Open of
the economizer damper at which the power exhaust is
needed. It can be set from 0 to 100% damper open.
Indoor Air Quality AQ
Indoor Air Quality (indoor sensor input): Terminal AQ accepts a
+2 to +10 Vdc signal with respect to the (AQ1) terminal. When
the signal is below it's set point, the actuator is allowed to
modulate normally in accordance with the enthalpy and mixed
air sensor inputs. When the AQ signal exceeds it's set point
setting and there is no call for free cooling, the actuator is
proportionately modulated from the 2 to 10 Vdc signal, with 2
Vdc corresponding to full closed and 10 Vdc corresponding to
full open. When there is no call for free cooling, the damper
position is limited by the IAQ Max damper position setting.
When the signal exceeds it's set point (Demand Control
Ventilation Set Point) setting and there is a call for free cooling,
the actuator modulates from the minimum position to the full
open position based on the highest call from either the mixed
air sensor input or the AQ voltage input.
• Optional CO
2
Space Sensor Kit Part # 2AQ04700324
• Optional CO
2
Sensor Kit Part # 2AQ04700424
Replace the top rear access panel on the unit.
Extreme care must be exercised in turning all set point,
maximum and minimum damper positioning adjustment
screws to prevent twisting them off.