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50VG-K: Installation Instructions
5. Charge unit with R-410A refrigerant, using an electronic scale.
Refer to unit rating plate for required charge.
Step 3 – Start-Up Adjustments
Complete the required procedures given in the Pre-Start-Up section
before starting the unit. Do not jumper any safety devices when
operating the unit. Do not operate the unit in cooling mode when the
outdoor temperature is below 40°F (4°C) (unless accessory low-ambient
kit is installed).
Checking and Adjusting Refrigerant Charge
The refrigerant system is fully charged with R-410A refrigerant and is
tested and factory sealed.
NOTE: Adjustment of the refrigerant charge is not required unless the
unit is suspected of not having the proper R-410A charge.
A subcooling charging chart is attached to the inside of the compressor
access panel. The chart includes the required liquid line temperature at
given discharge line pressures and outdoor ambient temperatures.
An accurate thermocouple- or thermistor-type thermometer, and a gauge
manifold are required when using the subcooling charging method for
evaluating the unit charge. Do not use mercury or small dial-type
thermometers because they are not adequate for this type of
measurement.
NOTE: Allow system to operate on high stage cooling for a minimum of
15 minutes before checking or adjusting refrigerant charge.
IMPORTANT: When evaluating the refrigerant charge, an indicated
adjustment to the specified factory charge must always be very minimal.
If a substantial adjustment is indicated, an abnormal condition exists
somewhere in the cooling system, such as insufficient airflow across
either coil or both coils.
1. Remove caps from low- and high-pressure service fittings.
2. Using hoses with valve core depressors, attach low- and
high-pressure gauge hoses to low- and high-pressure service
fittings, respectively.
3. Start unit and let run until system pressures stabilize.
4. Measure and record the following:
a. Outdoor ambient-air temperature (°F [°C] db).
b. Liquid line temperature (°F [°C]) at TXV.
c. Discharge (high-side) pressure (psig).
d. Suction (low-side) pressure (psig) (for reference only).
5. Using Cooling Charging Charts (See
temperature (°F [°C] db) with the discharge line pressure (psig) to
determine desired system operating liquid line temperature (See
Fig.
18).
6. Compare actual liquid line temperature with desired liquid line
temperature. Using a tolerance of ±2°F (±1.1°C), add refrigerant if
actual temperature is more than 2°F (1.1°C) higher than proper
liquid line temperature, or remove refrigerant if actual temperature
is more than 2°F (1.1°C) lower than required liquid line
temperature.
NOTE: If the problem causing the inaccurate readings is a refrigerant
leak, refer to Check for Refrigerant Leaks section.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig.
18) compare outdoor-air
14
Indoor Airflow and Airflow Adjustments
CAUTION
!
UNIT OPERATION HAZARD
Failure to follow this caution may result in unit damage.For cooling
operation, the recommended airflow is 350 to 450 cfm for each 12,000
Btuh of rated cooling capacity. For heating operation, the airflow must
produce a temperature rise that falls within the range stamped on the
unit rating plate.
NOTE: Be sure that all supply-air and return-air grilles are open, free
from obstructions, and adjusted properly.
WARNING
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Disconnect electrical power to the unit and install lockout tag before
changing blower speed.
This unit has independent fan speeds for low stage cooling and high
stage cooling. In addition, 208/230 VAC models have the
field-selectable capability to run an enhanced dehumidification
('DEHUM') speed on high stage cooling (as low as 320 CFM per ton).
Coupled with the improved dehumidification associated with low stage
cooling, the DHUM speed allows for a complete dehumidification
solution independent of cooling stage.
modes and the associated fan speeds with each mode:
Table 3 – Operation Modes and Fan Speeds
208/230 VAC Models
Operation Mode
Low Stage Cooling
High Stage Cooling
High Stage Enhanced
Dehumidification Cooling
Continuous Fan
460 VAC Models
Operation Mode
Low Stage Cooling
High Stage Cooling
Continuous Fan
CAUTION
!
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Disconnect electrical power to the unit and install lockout tag before
changing blower speed.
The evaporator fan motor is factory set to provide 5 different fan speeds
to choose from for the various operation modes (see
are factory-shipped for nominal high stage and low stage cooling airflow
operation at minimum external static pressure. See
Table 4 – Color Coding for Indoor Fan Motor Leads
Black = High Speed
Orange = Med-High Speed
Red = Med Speed
Pink = Med-Low Speed
Blue = Low Speed
Table 3
shows the operation
Fan Speed Tap
Connection
LOW
HIGH
DH
LOW
Fan Speed Tap Connection
LOW
HIGH
LOW
Table
4). All models
Table
2.
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