Question 1

How is additional line set charge calculated?

Accepted Answer

Subtract the length covered by the factory charge from the total line set length. Multiply the extra length by the manufacturer's charge rate in ounces per foot. This tool treats extra length below zero as zero.

Question 2

Where do the preset charge rates come from?

Accepted Answer

They are typical R-410A liquid line rates, not universal manufacturer specifications. Replace the preset with the rate from your equipment installation manual, especially for other refrigerants.

Question 3

Which line size should I select?

Accepted Answer

Select the liquid line outside diameter, not the suction line diameter. Confirm that the installed liquid line size is approved for your equipment and application.

Question 4

Does suction line size affect additional charge?

Accepted Answer

Many manufacturers calculate added charge from the liquid line length and size, but long line applications can have additional requirements. The calculator does not account for every system design, so follow the installation manual.

Question 5

What does a zero additional charge result mean?

Accepted Answer

It means the entered line set length is within the entered factory charge allowance. It does not confirm the system's existing charge or account for leaks, component changes or other manufacturer requirements.

Question 6

Should I verify the system after weighing in refrigerant?

Accepted Answer

Yes. Use a calibrated scale and follow the manufacturer's procedure. Once airflow and operating conditions are correct and stable, verify the specified superheat or subcooling target where the manual requires it.

Additional refrigerant charge calculator

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