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PY5G--B: Installation Instructions
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
10).
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 the Check for Refrigerant Leaks section.
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-and return-air grilles are open, free from
obstructions, and adjusted properly.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Table 10
Charts,"
compare
outdoor-air
!
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.
Single phase 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 or a thermostat that
supports 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.
23). For 3-phase models, the cooling speed is marked "LOW" on
the interface board (IFB) (See
noted in
Table
11. There are up 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
single phase models, one of the 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
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" speed is for high
static cooling only, and must not be used for gas heating. "High"
blower 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):
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.
Dehumidification Cooling Fan Speed Set-up :
IMPORTANT: Dehumidification control must open control circuit on
humidity rise above set point.
Use of the dehumidification cooling fan speed requires use of either a 24
VAC dehumidistat or a thermostat which includes control of a 24 VAC
dehumidistat connection. In either case, the dehumidification control
must open the control circuit on humidity rise above the
dehumidification set point.
1. Move shunt jumper on IGC board to "DH" (See
2. Refer to airflow table
the dehumidification cooling fan speed. Speeds that are not allowed
are shaded in
Table
11.
3. Connect selected speed tap wire to "DHUM" terminal on the IGC
board. Verify that static pressure is in the acceptable range for the
speed tap to be used for dehumidification cooling.
27
WARNING
Fig.
23). The factory-shipped settings are
Fig.
23).
Table 12
Table 1
Fig.
23).
(Table
11) to determine allowable speeds for
Table
9). For
to the system
Table 9
that
for each
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