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Set system selector switch at HEAT position and set thermostat
at a setting above room temperature. Set fan at AUTO position.
First stage of thermostat energizes the first-stage electric heater
elements; second stage energizes second-stage electric heater
elements, if installed. Check heating effects at air supply
grille(s).
If electric heaters do not energize, reset limit switch (located on
evaporator-fan scroll) by pressing button located between ter-
minals on the switch.
To shut off unit - set system selector switch at OFF position.
Resetting thermostat at a position below room temperature
temporarily shuts unit off until space temperature falls below
thermostat setting.
Ventilation (Continuous Fan)
Set fan and system selector switches at ON and OFF positions,
respectively. Evaporator fan operates continuously to provide
constant air circulation.
START-UP, PREMIERLINK CONTROLS
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury
or death.
The unit must be electrically grounded in accordance with
local codes and NEC ANSI/NFPA 70 (American National
Standards Institute/National Fire Protection Association.)
For details on operating 50KC**04-06 units equipped with the
factory-installed PremierLink controller option, refer to the
PREMIERLINK Retrofit Rooftop Controller Version 3.x In-
stallation, Start-up and Configuration Instructions.
Refer to PremierLink Retrofit Rooftop Controller Version 3.x
Installation, Start-up, and Configuration Instructions for full
discussion on configuring the PremierLink control system.
START-UP, RTU-OPEN CONTROL
For details on operating 50KC**04-06 units equipped with the
factory-installed RTU Open Controller option, refer to the Fac-
tory-Installed Option RTU Open Multi-Protocol Controller
Controls, Start-Up, Operation, and Troubleshooting manual.
OPERATING SEQUENCE
Base Unit Controls
Cooling - Units without Economizer
When thermostat calls for cooling, terminals G and Y1 are en-
ergized. The indoor-fan contactor (IFC) and compressor con-
tactor 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 will be en-
ergized with 24-v. The IFC and heater contactor no. 1 (HC1)
are energized.
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$er IV control in Unoccupied mode.
During Occupied mode operation, indoor fan operation will be
accompanied by economizer dampers moving to Minimum
Position set point for ventilation. If indoor fan is off, dampers
will close. During Unoccupied mode operation, dampers will
remain closed unless a Cooling (by free cooling) or DCV de-
mand is received.
Integrated EconoMi$er IV operation on 50KC single compres-
sor 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 ther-
mostat as described above in "Cooling - Units without econo-
mizer". 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 appropri-
ate changeover command (dry bulb, outdoor enthalpy, differen-
tial 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°F to 55°F. Compressor will not
run.
During free cooling operation, a supply air temperature (SAT)
above 50°F will cause the dampers to modulate between Mini-
mum Position set point 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. Damp-
ers will modulate to maintain SAT at 50°F to 55°F concurrent
with compressor operation. The Low Ambient Lockout Ther-
mostat will block compressor operation with economizer oper-
ation 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 set point and will be de-ener-
gized as the dampers close below the PE-On set point.
Damper movement from full closed to full open (or vice versa)
will take between 1
1
/
and 2
2
Heating, Unit with EconoMi$er IV
During Occupied mode operation, indoor fan operation will be
accompanied by economizer dampers moving to Minimum Po-
sition set point for ventilation. If indoor fan is off, dampers will
close. During Unoccupied mode operation, dampers will re-
main closed unless a DCV demand is received.
When the room temperature calls for heat (W1 closes), the
heating controls are energized as described in "Heating - Units
without economizer".
Demand Controlled Ventilation
If a field-installed sensor is connected to the EconoMi$er IV
control, a Demand Controlled Ventilation strategy will operate
automatically. As the level in the space increases above the set
point (on the EconoMi$er IV controller), the minimum posi-
tion of the dampers will be increased proportionally, until the
Maximum Ventilation setting is reached. As the space level de-
creases because of the increase in fresh air, the outdoor-damper
will follow the higher demand condition from the DCV mode
or from the free-cooling mode.
DCV operation is available in Occupied and Unoccupied peri-
ods with EconoMi$er IV. However, a control modification will
be required on the 50KC unit to implement the Unoccupied pe-
riod function.
53
1
/
minutes.
2
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