Bryant 580J*04--12 - Manual (Page 45)

45
During free cooling operation, a supply air temperature
(SAT) above 50_F will cause the dampers to modulate
between Minimum Position setpoint and 100% open. With
SAT from 50_F to 45_F, the dampers will maintain at the
Minimum Position setting. With SAT below 45_F, the
outside air dampers will be closed. When SAT rises to
48_F, the dampers will re--open to Minimum Position
setting.
Should 100% outside air not be capable of satisfying the
space temperature, space temperature will rise until Y2 is
closed. The economizer control will call for compressor
operation. Dampers will modulate to maintain SAT at 50
to 55_F concurrent with compressor operation. The Low
Ambient Lockout Thermostat will block compressor
operation with economizer operation below 42_F outside
air temperature.
When space temperature demand is satisfied (thermostat
Y1 opens), the dampers will return to Minimum Damper
position if indoor fan is running or fully closed if fan is
off.
If accessory power exhaust is installed, the power exhaust
fan motors will be energized by the economizer control as
the dampers open above the PE--On setpoint and will be
de--energized as the dampers close below the PE--On
setpoint.
Damper movement from full closed to full open (or vice
versa) will take between 1--1/2 and 2--1/2 minutes.
Heating With EconoMi$er IV
During Occupied mode operation, indoor fan operation
will be accompanied by economizer dampers moving to
Minimum Position setpoint for ventilation. If indoor fan is
off, dampers will close. During Unoccupied mode
operation, dampers will remain closed unless a DCV
demand is received.
When the room temperature calls for heat (W1 closes), the
heating controls are energized as described in Heating,
Unit Without Economizer above.
Demand Controlled Ventilation
If a field--installed CO
2
sensor is connected to the
EconoMi$er IV control, a Demand Controlled Ventilation
strategy will operate automatically. As the CO
2
level in
the space increases above the CO
2
setpoint (on the
EconoMi$er IV controller), the minimum position of the
dampers will be increased proportionally, until the
Maximum Ventilation setting is reached. As the space
CO
2
level decreases because of the increase in fresh air,
the outdoor--damper will follow the higher demand
condition from the DCV mode or from the free--cooling
mode.
DCV operation is available in Occupied and Unoccupied
periods with EconoMi$er IV. However, a control
modification will be required on the 580J unit to
implement the Unoccupied period function.
FASTENER TORQUE VALUES
See Table 18 for torque values.
Table 18 – Torque Values
Supply fan motor mounting 120 +/--- 12 in---lbs
Supply fan motor adjustment plate 120 +/--- 12 in---lbs
Motor pulley setscrew 72+/--- 5 in---lbs
Fan pulley setscrew 72+/--- 5 in---lbs
Blower wheel hub setscrew 72+/--- 5 in---lbs
Bearing locking collar setscrew 65---70 in---lbs
Compressor mounting bolts 65---75 in---lbs
Condenser fan motor mounting bolts 20 +/--- 2 in---lbs
Condenser fan hub setscrew 84 +/--- 12 in---lbs
580J