Carrier 48VL-E Installation Instructions Manual page 21

48VL-(E, F): Installation Instructions
WARNING
!
EXPLOSION HAZARD
Failure to follow this warning could result in
death, serious personal injury, and/or property
damage.
Never use air or gases containing oxygen for
leak testing or operating refrigerant compressors.
Pressurized mixtures of air or gases containing
oxygen can lead to an explosion.
NOTE: Adjustment of the refrigerant charge is not required unless the
unit is suspected of not having the proper Puron (R-410A) charge.
NOTE: Some units have fixed orifice refrigerant metering devices.
There is a different charging procedure for both expansion devices.
Refer to the correct procedure for your unit.
The charging label and the tables shown refer to system temperatures
and pressures in cooling mode only. A refrigerant charging label is
attached to the inside of the compressor access panel. (See
Subcool chart for units with TXV and superheat chart for units with
fixed orifice.) The chart includes the required liquid line temperature at
given discharge line pressures and outdoor ambient temperatures.
A superheat chart is attached to the inside of the compressor access panel
for the unit with fixed metering device. Refer to the charging procedure
on the label.
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.
CAUTION
!
UNIT DAMAGE HAZARD
Failure to follow this caution may result in unit damage.
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.
Proceed as follows:
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 in Cooling Mode and let unit 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]).
c. Discharge (high-side) pressure (psig).
d. Suction (low-side) pressure (psig) (for reference only).
5. Using "Cooling Charging
temperature (°F [°C] db) with the discharge line pressure (psig) to
determine desired system operating liquid line temperature (See
Table 8).
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
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 8
Charts," compare outdoor-air
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 the Check for Refrigerant Leaks section.
Indoor Airflow and Airflow Adjustments
!
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-and return-air grilles are open, free from
obstructions, and adjusted properly.
!
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 gas heating and cooling modes.
All models also have a dedicated continuous fan speed. All models (1
phase and 3 phase), have a field-selectable capability to run two different
cooling speeds: A normal cooling fan speed (350-450 CFM/Ton) and an
enhanced dehumidification fan speed (As low as 320 CFM/Ton) for use
with either a dehumidistat
dehumidification.
This unit is factory-set for use with a single cooling fan speed. For single
phase models, the cooling speed is marked "COOL" on the IGC (See
Fig. 18). The factory-shipped settings are noted in
to 3 additional speed tap wires available for use in either gas heating
mode, cooling mode, or continuous fan mode (For color coding on the
indoor fan motor leads, see Table
additional speed tap wires is connected to the continuous fan, with the
other 2 wires shipped loose in the control box near the IGC. For three
phase models, the additional 3 speed tap wires are shipped loose with
vinyl caps and are located in the control box near the interface fan board
(IFB) (See Fig. 18).
Gas Heating Fan Speed Set-up:
To change the gas heating speed:
1. Remove existing speed tap wire from the "HEAT" terminal on the
IGC.
2. Connect the desired speed tap wire on the "HEAT" terminal on the
IGC board. Make sure that the speed chosen delivers temperature
rise within the rise range listed on the unit. "High" fan speed is for
high static cooling only and must not be used for gas heating speed.
Cooling Fan Speed Set-up (Dehumidification feature
not used) (Single Phase Models):
To change cooling speed:
1. Remove existing speed tap wire from the "COOL" terminal on the
IGC board. Add the wet coil pressure drop in
static to determine the correct cooling airflow speed in
will deliver the nominal cooling airflow listed in
size.
2. Connect the desired speed tap wire on the "COOL" terminal on the
IGC board.
21
CAUTION
WARNING
or a thermostat that
Table 9. There are up
7). For single phase models, one of the
Table 11 to the system
Table 1
supports
Table 7 that
for each