CAUTION
Compressor damage will occur if system is incorrectly charged. On new system installations, charge the
system as specified in the Tabular Data Sheet for the matched coil and follow guidelines in this manual.
The factory charge in the outdoor unit includes enough charge for the unit, 15 ft (4.6 m) of
interconnecting refrigerant piping, and the smallest indoor coil match-up. Some indoor coil
matches may require additional charge. Refer to the Tabular Data Sheet for charge requirements.
To ensure that the unit performs at the published levels, it is important to determine the indoor
airflow and add refrigerant charge accordingly. To charge the system, follow these steps:
1. Measure the indoor airflow.
2. Determine the total system charge.
3. Use the indoor airflow and total system charge results to charge the unit.
4. Charge the indoor TXV in subcooling mode.
Measuring indoor airflow
About this task:
To determine the rated airflow for a specific match, consult the technical literature at http://
www.simplygettingthejobdone.com. When attempting to match this airflow, select the lowest
possible speed tap, measure the actual airflow, and adjust as necessary.
NOTICE
Prevent contamination
Ensure that different refrigerants are not mixed when using charging equipment, and keep hoses or
lines as short as possible to minimize refrigerant in them.
Grounding
Ensure that the refrigerating system is properly grounded before charging it with refrigerant
Labeling
Label the system when the charging process is complete, if not already labeled.
Leak testing
After charging but before commissioning, perform a leak test on the system, and conduct a follow-up
leak test before leaving the site.
To measure actual airflow, it is not an acceptable method to just check the jumper pin setting tables
and to assume 0.5 in. W.C. total external static pressure.
To determine indoor airflow, complete the following steps:
1. Measure the static pressure with a manometer between the filter and blower.
2. On a single-piece air handler, take a second reading in the supply air duct outside of the
unit. On a gas furnace, take the second reading after the heat exchanger but before the
indoor coil.
Installation Manual: R-454B Outdoor Split-System Air Conditioner40
Johnson Controls Ducted Systems
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