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5.
Be sure to ground the condensing unit by securing the
ground wire to the grounding lug inside the control
box.
6.
Be sure to follow National Electrical Code and all local
codes
NOTE: Use copper conductors only.
CAUTION:
Casing
permanently grounded in accordance with National Electric
Code or other applicable local codes.
SECTION 6. REFRIGERANT
CHARGE
Condensing units are supplied with a refrigerant charge (R-
22)
sufficient
for
typical
approximately
25
feet
Condensing unit liquid and suction valves are closed to
contain the charge within the unit.
MEASUREMENT
If a calibrated charging cylinder or accurate weighing device
is available, add refrigerant accordingly.
CAUTION: Refrigerant charging should only be
carried out by a qualified air conditioning contractor.
FIELD CHARGING
Depending on the type of restricting device that is installed
on the system (TXV, piston, capillary tubes, etc.), the
subcooling or superheat charging method can be used for
field charging or checking the existing refrigerant charge in
a system. Because each installation is different in terms of
indoor air flow, refrigerant line length, and duct variations,
etc., the factory charge may not be correct for every
application. To assure the best performance from the air
conditioner, the refrigerant charge should be checked and
adjusted when needed on each installation.
CAUTION:
Compressor damage will occur if
system is improperly charged. On new system installations,
charge the system per refrigerant charge information label
and follow guidelines in these instructions.
WARNING: Refrigerant is under pressure. Guard
against refrigerant spraying into the face or on skin. Always
wear protective equipment, i.e. safety glasses or goggles
and gloves when working with refrigerant.
Page 6
or
cabinet
must
matching
evaporator
of
interconnecting
tubing.
SUBCOOLING CHARGING METHOD
The subcooling charging method is to be used on units
which have Thermostatic Expansion Valve (TXV) as the
expansion device.
standard high side gauge is required for pressure readings.
1.
Measure the outdoor air temperature. (T1)
2.
Measure the liquid line pressure at the outdoor unit
and determine condenser refrigerant temperature by
be
the scale on the high side pressure gauge. (T2)
3.
Measure the liquid line temperature on the liquid line at
the outdoor unit. (T3)
4.
Subtract T3 from T2. (T2 – T3) This is the subcooling
value.
temperature (T1), to the chart on page 8 (Figure 3). If
the value is below the line, add refrigerant. If the value
is above the line, remove refrigerant charge.
and
NOTE: When removing refrigerant, always use standard
reclaim procedures.
NOTE: On cooler days (65degF or lower), attempts to
operate the air conditioner and take gauged pressure
readings may be unsuccessful, as unusually low pressures
will be observed on the suction line. This type of operation
may give the impression of an undercharged unit. Such is
NOT necessarily the case. The low-pressure reading may
exist because of the large condenser surface area and the
cold ambient air removing so much heat from the
refrigerant.
pressures. Adding refrigerant in cold weather will result in
an overcharged unit, which may then trip out on high
pressure limit during warm or hot weather. Line pressures
should not be taken for test purposes when the outdoor
temperature is below 70degF since a false reading may
occur. Do not attempt to operate the air conditioner on a
day of 45degF or cooler.
For proper subcooling readings, a
Compare this value and the outdoor
Sub-cooling occurs and results in very low
Installer's Information Manual
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