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To calculate additional charge requried for a 25-ft line set:
25 ft - 15 ft = 10 ft X 0.6 oz/ft=6ozofadditional charge.
B. COOLING ONLY PROCEDURE
UNITS WITH COOLING MODE PURON® TXV
Units installed with cooling mode TXV require charging by the
subcooling method.
1. Operate unit a minimum of 10 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 tempera-
ture.
5. Refer to Table 3. Find the point where required subcooling
temperature intersects measured liquid service valve pres-
sure.
6. To obtain required subcooling temperature at a specific
liquid line pressure, add refrigerant if liquid line tempera-
ture is higher than indicated or reclaim refrigerant if
temperature is lower. Allow a tolerance of ± 3°F.
UNITS WITH INDOOR PISTONS
Units installed with indoor pistons require charging by the super-
heat method.
The following procedure is valid when indoor airflow is within ±
21 percent of its rated CFM.
1. Operate unit a minimum of 10 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 thermom-
eter.
5. Measure indoor air (entering indoor coil) wet-bulb tempera-
ture with a sling psychrometer.
6. Refer to Table 4. Find outdoor temperature and evaporator
entering air wet-bulb temperature. At this intersection, note
superheat.
7. Refer to Table 5. Find superheat temperature located in item
6 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.
XIII. FINAL CHECKS
IMPORTANT: Before leaving job, be sure to do the following:
1. Ensure that all wiring and tubing is secure in unit before
adding panels and covers. Securely fasten all panels and
covers.
2. Tighten service valve stem caps to 1/12-turn past finger
tight.
3. Leave User’s Manual with owner. Explain system operation
and periodic maintenance requirements outlined in manual.
4. Fill out Dealer Installation Checklist and place in customer
file.
CARE AND MAINTENANCE
For continuing high performance and to minimize possible equip-
ment failure, periodic maintenance must be performed on this
equipment.
Frequency of maintenance may vary depending upon geographic
areas, such as coastal applications. See Users Manual for informa-
tion.
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