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Additional Refrigerant Charge Calculation Error During Commissioning

Likely causes

Only partial pipe sections reflected in additional charge calculation — missed sections

Check: Re-measure entire liquid line from piping drawings → sum all liquid line lengths (m) from outdoor unit → branch pipes → each indoor unit

What to do: Re-sum total liquid line length from drawings → recalculate additional charge amount per manufacturer table → perform additional charge using scale weighing method

Factory-supplied base charge omitted from or double-counted in calculation

Check: Check base charge on outdoor unit nameplate → verify if base charge was subtracted in additional charge calculation → re-review calculation sheet

What to do: Recalculate additional charge after subtracting base charge → add or recover the difference from current charge → verify suction superheat 5–8°C, liquid line subcooling 5–15°C

Wrong refrigerant type or model row referenced in manufacturer's charge table

Check: Re-confirm outdoor unit model name and refrigerant type on nameplate → cross-check 3 criteria in manufacturer commissioning manual: model, refrigerant type, liquid line diameter

What to do: Recalculate additional charge using correct model/refrigerant/liquid line diameter row → adjust current charge (recover or add) → verify operating conditions (suction superheat 5–8°C, subcooling 5–15°C)

Field tip

After calculating additional charge, always confirm subtraction of outdoor unit base charge (nameplate or tech sheet). Matching to the gram prevents overcharge/undercharge.

All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.

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