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Economizer
Economizer Exists
This point tells the controller if there is an economizer
installed onthe unit.
FactoryDefault = NO if no economizer
YES if thereis an economizer installed
Economizer Minimum Position
This defines the lowest economizer position when the
indoor fan is running and the building is occupied.
FactoryDefault = 20%
Range = 0--100%
Economizer High OAT Lockout
If the outdoor air temperature rises above this value,
economizer cooling will be disabled and dampers will
return andstay at minimum position.
FactoryDefault = 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.
FactoryDefault = 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 NOt he
power exhaust will be controlled by the Power Exhaust
Setpoint.
FactoryDefault = NO
IAQ
Max Differential CO2Setpt
If the difference between indoor an outdoor air quality
becomes greater then this value the damperposition will
stay at the IAQ Greatest Min Dmpr Pos. configuration
point
FactoryDefault = 650 PPM
Range = 300--950PPM
IAQ Greatest Min Dmpr Pos.
This is the greatest minimum positionthe economizer will
open to while trying to control the indoor air quality, CO2
differential.
Factory Default = 50% open
Range = 10--60%open
Clockset
This submenu screen allowsyou to set the date and time
manually. The Daylight Savings Time (DST) can also be
changedhere. The date and time isautomatically 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.
FactoryDefault = 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
Admini strator Pas sword (1111). Th e ADMIN passwor d
will always override the user password.
OPERATINGSEQUENCES

Base Unit Controls

Cooling, Units Without Economizer

Whenthermostat 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 WithoutEconomizer

When the thermostat calls for heating, terminal W1 is
energized. Topre vent 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 stage s
of heat, when additional heat is needed, W2 is energized
and the high--firesolenoi d on the main gas valve (MGV)
is energized. When the thermostat is satisfiedand 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$er IV, there
must be a 24--v signal at terminals TR and N (provided
through PL6--3 from the unit’s IFCc oil). Removing the
signal at N places the EconoMi$er IV control in
Unoccupied mode.
During Occupied mode operation, indoor fan operation
will be accompanied by economizer dampers moving to
Minimum Position setpointfor 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--stagethermostat (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 Positionas 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 ope n and
closed to maintain the unit supply air temperature at 50 to
55_F.Compressor will not run.
48TC