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Economize r
Economize r Exists
This point tells the controller if there is an economizer
installed on the unit.
Factory Default = NO if no economizer
YES if there is an economizer installed
Economize r Minimum Position
This defines the lowest economizer position when the
indoor fan is running and the building is occupied.
Factory Default = 20%
Range = 0--100 %
Economize r High OAT Lockout
If the outdoor air temperature rises above this value,
economizer cooling will be disabled and dampers will
return and stay at minimum position.
Factory Default = 75_F
Range = 55--80_F
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.
OPERATI NG SEQUENCES
Base Unit Controls
Cooling, Un its Without Economizer
When thermostat calls for cooling, terminals G and Y1 are
energized. The indoor--fan contactor (IFC) and
compressor contactor are energized and indoor--fan motor,
compressor, and outdoor fan starts. The outdoor fan motor
runs continuously while unit is cooling.
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. On units equipped for two stages
of heat, when additional heat is needed, W2 is energized
and the high--fire solenoid on the main gas valve (MGV)
is energized. When the thermostat is satisfied and W1 is
deenergized, 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$er IV control in
Unoccupied mode.
During Occupied mode operation, indoor fan operation
will be accompanied by economizer dampers moving to
Minimum Position setpoint for ventilation. If indoor fan is
off, dampers will close. During Unoccupied mode
operation, dampers will remain closed unless a Cooling
(by free cooling) or DCV demand is received.
Integrated EconoMi$er IV operation on 48TC single
compressor model requires a 2--stage thermostat (Y1 and
Y2 switches).
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, Without
Economizer. Outside air damper position will be closed or
Minimum Position as determined by occupancy mode and
fan signal.
When free cooling is available as determined by the
appropriate changeover command (dry bulb, outdoor
enthalpy, differential dry bulb or differential enthalpy), a
call for cooling (Y1 closes at the thermostat) will cause
the economizer control to modulate the dampers open and
closed to maintain the unit supply air temperature at 50 to
55_F. Compressor will not run.
48TC