Bryant F - Manual (Page 67)

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Power Exhaust Setpt
When the economizer damper position opens above this
point the power exhaust operation will begin. When the
damper position falls 10% below the setpoint, the power
exhaust will shutdown.
Factory Default = 50%
Range = 20--90 %
NOTE: This point is only used when Continuous Occ
Exhaust = NO
Continuous Occ Exhaust
This point tells the controller when to run the power
exhaust if equipped on the unit. If set to YES, the power
exhaust will be on all the time when in occupied mode
and will be off when in unoccupied mode. If set to NO the
power exhaust will be controlled by the Power Exhaust
Setpoint.
Factory Default = NO
IAQ
Max Differential CO
2
Setpt
If the difference between indoor an outdoor air quality
becomes greater then this value the damper position will
stay at the IAQ Greatest Min Dmpr Pos. configuration
point
Factory Default = 650 PPM
Range = 300--950 PPM
IAQ Greatest Min Dmpr Pos.
This is the greatest minimum position the economizer will
open to while trying to control the indoor air quality, CO
2
differential.
Factory Default = 50% open
Range = 10--60% open
Clockset
This submenu screen allows you to set the date and time
manually. The Daylight Savings Time (DST) can also be
changed here. The date and time is automatically set when
ever software is downloaded. The clock is a 24 hour clock
and not am/pm. The time should be verified (and maybe
changed) according to unit location and time zone.
Factory Default = Eastern Standard Time
USERPW
This submenu screen allows you to change the user
password to a four number password of choice. The User
password change screen is only accessible with the
Administrator Password (1111). The ADMIN password
will always override the user password.
OPERATING SEQUENCES
Base Unit Controls
Cooling, Units Without Economizer
When thermostat calls for Stage 1 cooling, terminals G
and Y1 are energized. The indoor--fan contactor (IFC),
outdoor fan contactor (OFC) and Compressor 1 contactor
(C1) are energized and indoor-fan motor, outdoor fan and
Compressor 1 start. The outdoor fan motor runs
continuously while unit is in Stage 1 or Stage 2 cooling.
(08D,F and 12D,F units have two outdoor fans; both run
while unit is in Stage 1 or Stage 2 cooling.)
If Stage 1 cooling does not satisfy the space load, the
space temperature will rise until thermostat calls for Stage
2 cooling (Y2 closes). Compressor 2 contactor (C2) is
energized; Compressor 2 starts and runs.
Heating, Units Without Economizer
When the thermostat calls for heating, terminal W1 is
energized. To prevent thermostat short-cycling, the unit is
locked into the Heating mode for at least 1 minute when
W1 is energized. The induced-draft motor is energized
and the burner ignition sequence begins. The indoor
(evaporator) fan motor (IFM) is energized 45 seconds
after a flame is ignited.
If Stage 1 heating does not satisfy the space load, the
space temperature will fall until thermostat calls for Stage
2 heating (W2 closes). Terminal W2 is energized and the
high-fire solenoid on the main gas valve (MGV) is
energized. Firing rate increases to high-fire. When space
load is partially satisfied, terminal W2 is de--energized;
the high-fire solenoid is de--energized and heating
operation continues on low--fire.
When the space heating load is fully satisfied, thermostat
terminal W1 is also deenergized. All heating operations
cease. The IFM stops after a 45-second time off delay.
Cooling, Unit With EconoMi$er IV
For Occupied mode operation of EconoMi$er IV, there
must be a 24-v signal at terminals TR and N (provided
through PL6-3 from the unit’s IFC coil). Removing the
signal at N places the EconoMi$er IV control in
Unoccupied mode.
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 Cooling
(by free cooling) or DCV demand is received.
When free cooling using outside air is not available, the
unit cooling sequence will be controlled directly by the
space thermostat as described above as Cooling, Unit
Without Economizer. Outside air damper position will be
closed or Minimum Position as determined by occupancy
mode and fan signal.
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