Application Data - Carrier 50HJQ004-016 Product Data

On a rise in room temperature, cooling contactor no. 1 in the
thermostat closes. The indoor and outdoor fan motors start. If the
5-minute compressor time-delay (CTD) on the defrost board
(DB) is satisfied, then compressor no. 1 (50HJQ016) or unloaded
compressor (50HJQ014) contactor is energized and compressor
will start. Compressor cycles on demand of the thermostat to
satisfy room conditions. Each time the cooling contactor no. 1
opens, the CTD starts the 5-minute delay.
On 50HJQ016 units, with an additional rise in room temperature,
cooling contactor no. 2 in the thermostat closes, energizing
compressor contactor no. 2. Compressor
on demand of the thermostat to satisfy the occupied space
demands.
On 50HJQ014 units, compressor runs fully loaded on a call for
second-stage cooling.
Cooling, units with economizer — Upon a call for cooling,
when outdoor ambient temperature is above the temperature
control setting, the indoor and outdoor fans and compressor(s)
energize. The economizer damper moves to vent position.
Upon a first-stage call for cooling, when outdoor ambient
temperature is below the temperature control setting, the indoor
fan starts and economizer damper modulates to maintain
mixed-air temperature. The compressor(s) remains off.
Upon a second-stage call for cooling, compressor no. 1
(50HJQ016) or loaded compressor (50HJQ014) is energized and
mechanical cooling is integrated with economizer cooling.
Compressor no. 2 (50HJQ016) is locked out. If the air
temperature is below 50 F, a cooling lockout switch prevents the
compressor(s) from running.
When supply-air temperature drops below a fixed set point, the
economizer damper modulates to maintain the temperature at the
fixed set point.
A freeze protection thermostat (FPT) is located on the indoor coil.
It detects frost build-up and turns off the compressor(s), allowing
the coil to clear. Once frost has melted, the compressor can be
reenergized.
Heating, units without economizer — With unit main power
on, set thermostat at HEAT position and desired room
temperature. Set fan switch at AUTO. (on demand) or ON
(continuous) position.
On a drop in room temperature, heating contactor no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor no. 2 contactor. Compressor (size 014) or compressor
no. 2 (size 016) and indoor and outdoor fan motors start. If the
5-minute CTD on the DB is satisfied, then compressor no. 1
contactor is energized and compressor no. 1 will start.
On units equipped with electric heat, when additional heat is
needed, heating contactor no. 2 in the thermostat closes,
energizing W2.
Heating, units with economizer — With unit main power on, set
thermostat at HEAT position and desired room temperature. Set
fan switch at AUTO. (on demand) or ON (continuous) position.
On a drop in room temperature, heating contactor no. 1 in the
thermostat closes, energizing heat relay (HR), reversing valve
relay (RVR), reversing valve solenoids (RVS1 and RVS2) and
compressor no. 2 contactor. Compressor no. 2 (016) and indoor
and outdoor fan motors (014,016) start. If the 5-minute CTD on
the DB is satisfied, then compressor (014) or compressor no. 1
(016) contactor is energized and compressor (014) or compressor
no. 1 (016) will start. The outdoor-air damper stays at vent
position while the indoor fan is operating.
On units equipped with electric heat, when additional heat is
needed, heating contactor no. 2 in the thermostat closes,
energizing W2.
no. 2 starts and cycles
UNIT
50TFQ
005 005
012
008-012 008 012
187
Defrost cycle — When the temperature of the outdoor coil drops
below 28 F as sensed by the defrost thermostat (DFT1 or DFT2),
the defrost timer starts. At the end of a timed period (field set at
30, 50, or 90 minutes), the defrost cycle will begin. The defrost
board energizes terminals O and W2, energizes the defrost relay
(DR), deenergizes the reversing valve solenoids (RVS1 and
RVS2), and energizes the electric heat. The outdoor-fan motor
will stop.
The unit continues to defrost either until the coil temperature as
measured by DFT1 or DFT2 reaches 65 F, or until unit completes
a 10-minute defrost cycle.
During the defrost mode, when a circuit defrosts, RVS will
oscillate between heating and cooling modes until defrost mode is
complete. This will prevent the head pressure from getting too
high.
At the end of the defrost cycle, the electric heaters (if applicable)
will be deenergized, the reversing valve solenoids will be
energized, and the outdoor fans will start.

APPLICATION DATA

Outdoor installation — Units approved for outdoor installation
only.
Ductwork — Secure vertical discharge ductwork to roof curb.
For horizontal discharge applications, either attach ductwork to
unit, or use field-supplied flanges attached to the horizontal
discharge openings and attach all ductwork to flanges.
Horizontal EconoMi$er2 — A field-installed accessory is
available for horizontal discharge applications. Field-installed
power exhaust accessory also available for vertical or horizontal
EconoMi$er2 applications.
Thru-the-bottom power connections — For applications
requiring thru-the-bottom connections,
thru-the-bottom package must be purchased to ensure proper
connections.
Thermostat — Use of 2-stage heating and cooling thermostat is
recommended for all units. A 2-stage cooling thermostat is
required on units with accessory economizer to provide integrated
cooling. A two-stage thermostat
50HJQ008-016 units.
Heating-to-cooling changeover — All units are automatic
changeover from heating to cooling when automatic changeover
thermostat and subbase are used.
Airflow — Units are draw-thru on cooling and blow-thru on
heating.
Maximum airflow — To minimize the possibility of condensate
blow-off from indoor coil, airflow through units should not
exceed 500 cfm/ton.
Minimum airflow — For cooling, minimum airflow is 300
cfm/ton. For 50TFQ units with electric heating, required
minimum cfm is 900 for 50TFQ004; 1200 for 50TFQ005; 1500
for 50TFQ006; 1800 for 50TFQ007; 2250 for 50TFQ008; 2500
for 50TFQ009; and 3000 for 50TFQ012, with the following
exceptions:
UNIT HEATER
VOLTAGE kW
230 230 10.4 10 4
208/230 42.4
208/230 50.0
460 50.0
17.0
575 575
34.0
For 50HJQ units with electric heating, required minimum cfm is
900 for 50HJQ004; 1200 for 50HJQ005; 1500 for 50HJQ006;
1700 for 50HJQ007; 2250 for 50HJQ008; 2500 for 50HJQ009;
Carrier accessory
is required for
REQUIRED
UNIT
MINIMUM
CONFIGURATION
CFM
Horiz or Vert Horiz or Vert 1400 1400
Horizontal 3200
Horizontal 3200
Horizontal
or
3200
Vertical
Horizontal o o ta
2800
or or
2350
Vertical
all