Step 13 -Check Charge - Carrier 25HPA Performance Series Installation Instructions Manual

STEP 13 —Check Charge
Factory charge and charging methods are shown on unit rating
plate. To check charge in cooling mode, refer to Cooling Only
Procedure. To check charge in heating mode, refer to Heating
Check Chart Procedure.
With unit operating, charge Puron refrigerant units with liquid
using a commercial type metering device in manifold hose.
Charge refrigerant into suction line. Some refrigerant cylinders
may contain a dip tube that allows liquid refrigerant to flow from
cylinder in upright position. Check cylinder label for correct
position to allow liquid flow.
Cooling Only Procedure
NOTE:
If subcooling charging conditions are not favorable,
charge must be weighed in accordance with unit rating plate,
±0.6 oz./ft of 3/8 in. liquid line above or below 15 ft,
respectively. Favorable conditions fall within the ranges given on
the charging chart on the outdoor unit plate.
EXAMPLE:
To calculate additional charge required for a 25 ft. line set:
25 ft. --- 15 ft. = 10 ft. X 0.6 oz/ft. = 6 oz. of additional
charge.
Units installed with cooling mode TXV require charging with
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
temperature.
5. Refer to Table 4. 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.
Heating Check Chart Procedure
To check system operation during heating cycle, refer to the
Heating Check Chart on outdoor unit. This chart indicates
whether a correct relationship exists between system operating
pressure and air temperature entering indoor and outdoor units. If
pressure and temperature do not match on chart, system
refrigerant charge may not be correct. Do not use chart to adjust
refrigerant charge.
NOTE: In heating mode, check refrigerant charge only when
pressures are stable. If in doubt, remove charge and weigh in
correct refrigerant charge.
NOTE: When charging is necessary during heating season,
charge must be weighed in accordance with unit rating plate ±0.6
oz./ft of 3/8 in. liquid line above or below 15 ft, respectively.
EXAMPLE:
To calculate additional charge required for a 25 ft. line set:
25 ft. --- 15 ft. = 10 ft. X 0.6 oz/ft. = 6 oz. of additional
charge.
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