Installation guide
11
charging charts prior to using these Heating-mode
charge verification charts. Always use safe and
environmentally sound methods when handling
refrigerant handling or servicing the unit. Review
the factory literature and safety warnings prior to
servicing.
• Whenrepairingsystemleaks,alwaysuseanitrogen(inert)
gas to protect the refrigerant system and pressure check
the repair before re-charging. Always replace the filter-
dryers when performing any repair to the refrigeration
system with one capable of acid removal. After completing
the repairs, evacuate the system to 350 - 500 microns
and weigh in the refrigerant to the amount specified on
the unit rating label.
• Beforeusingtheheatmodevericationtables,determine
the outdoor ambient temperature and the return air
temperature to the unit. Locate the appropriate location on
the units verification chart based on those measurements
to determine the ideal discharge pressure and temperature.
See Table 5, Table 6, & Table 7 (page 12). Verify the
outdoor fan and compressor are running and the outdoor
coil is free from frost accumulation. Also verify the system
is not operating in defrost mode before inspecting the
system.
• Alwaysusequalityinstrumentsthatareingoodworking
order to measure the actual operating point of the
refrigeration system. The discharge temperature should
be within 2 degrees of the ideal value and the pressure
should be within 2%.
• Themostreliablewayofverifyingthesystemisatthe
correct charge is to evacuate the system and weigh in
the charge to the amount shown on the rating label.
However, if an inspection with these verification charts
does not line up with the values shown and the ambient
temperature is above 50˚ F, then a more accurate way to
inspect the system for proper charge is with the cooling
mode charging charts. Switch the unit into cooling mode
and allow it to operate and stabilize for a few minutes then
inspect the unit operation with the cooling mode charts
and procedures.
Before changing the unit charge, always inspect the
following items first:
1. Inspect the liquid line temperature on the inlet and outlet
of the filter dryers. If it is the factory dryer and in good
condition there should be no temperature difference. If the
temperature difference is larger than 5˚, replace the filter
dryer with one that is bi-directional and has acid removal
capability. Refer to the unit RPL for the recommended
part number and size.
2. Inspect the units input voltage. Units operating at less
than 95% of the nominal voltage may deviate more from
the chart then previously stated.
3. Inspect the input voltage for a phase imbalance. Units with
greater then a 2% disparity will not operate at the rated
performance.
4. Verify that the unit filters are installed and are clean. The
pressure drop across the filters should not exceed 0.08
in-W.C.
5. Inspect the indoor coil, indoor blower and blower motor
for cleanliness, clogging, and proper operation.
6. Inspect the system for leaks. If any leaks are detected,
repair them immediately. Re-inspect the return air and
ambient temperatures and verify that the correct system
point on the verification chart was selected.
DO NOT use the charts in systems that have the fan cycling
under a low-ambient control. Low-ambient controls are for
cooling operation. In heating mode, the low ambient control
should be disabled. Unless the unit is in defrost mode, the
outdoor fan should always operate in conjunction with the
compressor.
IMPORTANT NOTE:
If the unit is equipped with a liquid valve with an outdoor
restrictor as shown in Figure 2 (page 4), then it
is not possible to measure the liquid pressure. To
approximate the liquid pressure, subtract 7 psig from
the discharge pressure.
Shaded boxes indicate flooded conditions.
Rated design values. The suction pressure will vary from design value if outdoor air flow, entering dry
bulb, or entering wet bulb temperatures vary.
1. All pressures are listed in psig and all temperatures in ° F
2. Discharge temperatures greater than charted values indicate an undercharged system.