Carrier 50HJQ004-016 Product Data page 186

compressors will be controlled by the PremierLink controller
using a PID Error reduction calculation.
The PremierLink controller will use the following information to
determine if free cooling is available:
S Indoor fan has been on for at least 30 seconds.
S The SPT, SAT, and OAT inputs must have valid
readings.
S OAT must be less than 75_F.
S OAT must be less than SPT.
S Enthalpy must be LOW (may be jumpered if and
enthalpy sensor is not available).
S Economizer position is NOT forced.
When free cooling is available, the outdoor-air damper is
positioned through the use of a Proportional Integral (PID)
control process to provide a calculated supply-air temperature
into the zone. The supply air will maintain the space temperature
between the heating and cooling set points.
The PremierLink control will integrate the compressors stages
with the economizer based on similar logic as the three routines
listed in the previous section. The SASP will float up and down
based on the error reduction calculations that compare space
temperature and space set point. The reversing valves will be
energized.
If an optional power exhaust is installed, as the outdoor-air
damper opens and closes, the power exhaust fans will be
energized and deenergized.
If field-installed accessory CO
PremierLink control, a PID-controlled demand ventilation
strategy will begin to operate. As the CO
increases above the CO set point, the minimum position of the
2
damper will be increased proportionally. As the CO
decreases because of the increase in fresh air, the outdoor-air
damper will be proportionally closed.
Heating, unit with EconoMi$er2, PremierLink control and a
room sensor- -- -Every 40 seconds the controller will calculate the
required heat stages (maximum of 3) to maintain Supply Air
Temperature (SAT) if the following qualifying conditions are
met:
S Indoor fan has been on for at least 30 seconds.
S COOL mode is not active.
S OCCUPIED, TEMP.COMPENSATED START or
HEAT mode is active.
S SAT reading is available.
S Fire shutdown mode is not active.
If all of the above conditions are met, the number of heat stages is
calculated; otherwise the required number of heat stages will be
set to 0.
If the PremierLink controller determines that heat stages are
required, the economizer damper will be moved to minimum
position if occupied and closed if unoccupied.
Defrost (50TFQ004-007, 50HJQ004-007, 50HEQ003- -006) —
As frost builds up on the outdoor coil, the coil temperature drops
below 28_F. When this outdoor-coil temperature drop is sensed
by the defrost thermostat (DFT) and the defrost timer is at the end
of a timed period (adjustable at 30, 50, or 90 minutes), the unit
operates in a defrost cycle controlled by the defrost timer and
thermostat. During this cycle, the reversing valve solenoid (RVS)
is energized and the outdoor fan shuts off. The electric heaters (if
installed) will be energized.
The unit continues to defrost until the coil temperature as
measured by DFT reaches 65_F, or the duration of defrost cycle
completes a 10-minute period.
sensors are connected to the
2
level in the zone
2
level
2
At the end of the defrost cycle, the electric heaters (if installed)
and the reversing valve will be deenergized, and the outdoor-fan
motor will be energized. The unit will now operate in the Heating
mode.
If the thermostat is satisfied during a defrost cycle, the unit will
continue in the Defrost mode until the time or temperature
constraints are satisfied.
Defrost (50TFQ008-012 and 50HJQ008-012) — When the
temperature of the outdoor coil drops below 28_F as sensed by
the defrost thermostat (DFT2) and the defrost timer is at the end
of a timed period (adjustable at 30, 50, or 90 minutes), reversing
valve solenoids (RVS1 and RVS2) are energized and the OFC is
deenergized. This switches the position of the reversing valves
and shuts off the outdoor fan. The electric heaters (if installed)
will be energized.
The unit continues to defrost until the coil temperature as
measured by DFT2 reaches 65_F, or the duration of defrost cycle
completes a 10-minute period.
During the Defrost mode, if circuit 1 defrosts first, RVS1 will
oscillate between Heating and Cooling modes until the Defrost
mode is complete.
At the end of the defrost cycle, the electric heaters (if installed)
will be deenergized; the reversing valves switch and the
outdoor-fan motor will be energized. The unit will now operate in
the Heating mode.
If the space thermostat is satisfied during a defrost cycle, the unit
will continue in the Defrost mode until the time or temperature
constraints are satisfied.
Automatic changeover — When the system selection switch is
set at AUTO. position, unit automatically changes from heating
operation to cooling operation when the temperature of the
conditioned space rises to the cooling level setting. When the
temperature of the conditioned space falls to the heating level
setting, unit automatically changes from cooling to heating
operation (with a 3°F deadband in between).
Continuous air circulation — Turn unit power on. Set system
control at OFF position. Set fan switch at ON position. The
indoor-fan contactor is energized through the thermostat switch
and the indoor fan runs continuously.
Cycle-LOC™ protection — If unit operation is interrupted by an
open high-pressure switch, low-pressure switch, indoor coil
freeze stat, or by compressor internal line-break device
(overcurrent or overtemperature), and compressor is calling for
either cooling or heating, Cycle-LOC protection device
simultaneously locks out unit and lights a warning light on the
thermostat. Restart the unit by manually turning thermostat to
OFF and then to ON position. If any of the protective devices
opens again, the unit continues to lock out until corrective action
is taken.
NOTE: If the unit fails to operate due to compressor over-current
condition, restart by manually resetting circuit breakers at the
unit. Restart cannot be accomplished at the room thermostat.
Emergency heat — If compressor is inoperative due to a tripped
safety device (high or low pressure, indoor coil freeze stat,
overcurrent, or overtemperature), the Cycle-LOC device locks out
the compressor and lights a warning light on the room thermostat.
When the switch is on (thermostat is set to the EM HT position),
compressor circuit and outdoor thermostats are bypassed, and the
second stage of thermostat energizes the indoor blower and the
electric resistance heaters.
Sequence of operation — 50HJQ014,016
Cooling, units without economizer — With unit main power
on, set thermostat to COOL position and desired room
temperature. Set fan switch at AUTO. (on demand) or ON
(continuous) position.
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