INSTALLATION INSTRUCTIONS R−410A Split System Air Conditioner
421 01 5103 00 13
A. UNITS WITH COOLING MODE TXV
Units installed with cooling mode TXV require charging
by the subcooling method.
1. Operate unit a minimum of 15 minutes before
checking charge.
2. Measure liquid service valve pressure by
attaching an accurate gage to service port.
3. Measure liquid line temperature by attaching an
accurate thermistor type or electronic
thermometer to liquid line near outdoor coil.
4. Refer to unit rating plate for required subcooling
temperature.
5. Refer to Figure 14. Find the point where required
subcooling temperature intersects measured
liquid service valve pressure.
6. To obtain required subcooling temperature at a
specific liquid line pressure, add refrigerant if
liquid line temperature is higher than indicated or
reclaim refrigerant if temperature is lower. Allow a
tolerance of "3_F (|1.7_C).
B. UNITS WITH INDOOR PISTON
Units installed with indoor pistons require charging by the
superheat method.
The following procedure is valid when indoor airflow is
within "21 percent of its rated CFM.
1. Operate unit a minimum of 15 minutes before
checking charge.
2. Measure suction pressure by attaching an
accurate gage to suction valve service port.
3. Measure suction temperature by attaching an
accurate thermistor type or electronic
thermometer to suction line at service valve.
4. Measure outdoor air dry−bulb temperature with
thermometer.
5. Measure indoor air (entering indoor coil) wet−bulb
temperature with a sling psychrometer.
6. Refer to Figure 12. Find outdoor temperature and
evaporator entering air wet−bulb temperature. At
this intersection, note superheat. Where a dash
(−−) appears on the table, do not attempt to
charge system under these conditions or
refrigerant slugging may occur. Charge must be
weighted in, adding or removing 0.6 oz/ft of 3/8
liquid line above or below 15 feet (4.6m)
respectively.
7. Refer to Figure 13. Find superheat temperature
(from #6 above) and suction pressure. At this
intersection, note suction line temperature.
8. If unit has a higher suction line temperature than
charted temperature, add refrigerant until charted
temperature is reached.
9. If unit has a lower suction line temperature than
charted temperature, reclaim refrigerant until
charted temperature is reached.
10. When adding refrigerant, charge in liquid form into
suction service port using a flow−restricting
device.
11. If outdoor air temperature or pressure at suction
valve changes, charge to new suction line
temperature indicated on chart.
12. Optimum performance will be achieved when
the operating charge produces 10_F suction
superheat at suction service valve with 95_F
(35_C) outdoor ambient and 80_F (27_C) dry
bulb (67_F / 19_C) wet bulb) indoor
temperature (DOE “A” test conditions) at
rated airflow.
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