Refrigerant Line Charge Calculator

About the Refrigerant Line Charge Calculator

Estimates the additional refrigerant charge needed for line sets longer than the factory-charged length, based on liquid-line diameter.

How to use this calculator

1. Enter the base line length included in the system charge and the actual installed line length.
2. Enter the manufacturer charge per extra length, such as ounces per foot or grams per meter.
3. Compare the actual line length to the included length to find the extra length.
4. Review the calculated extra refrigerant amount and add only what the equipment manufacturer specifies.

The formula explained

The calculator computes extra refrigerant as the added charge for the line length beyond the included length. In simple form, it uses \(\text{extra charge} = (\text{actual length} - \text{included length}) \times \text{charge per unit length}\).

• actual length = the full installed length of the refrigerant line set
• included length = the line length covered by the factory refrigerant charge
• charge per unit length = the amount of refrigerant needed for each extra foot or meter
• extra charge = the additional refrigerant required beyond the base charge

Step by step method

1. Find the difference between the actual line length and the included length, using \(\text{extra length} = \text{actual length} - \text{included length}\).
2. Multiply the extra length by the charge per unit length, using \(\text{extra charge} = \text{extra length} \times \text{charge per unit length}\).
3. If the actual line length is not longer than the included length, the extra charge is \(0\).

Worked example

Problem. A system includes refrigerant for \(25\) ft of line set. The installed line set is \(40\) ft, and the manufacturer requires \(0.6\) oz of refrigerant per extra foot. How much extra refrigerant is needed?

1. Compute the extra length: \(40 - 25 = 15\) ft.
2. Multiply by the charge rate: \(15 \times 0.6 = 9\) oz.
3. The system needs \(9\) oz of extra refrigerant.

Tips and common mistakes

• Always use the equipment maker's charge rate, because different systems can have different requirements.
• Make sure your units match, so feet are paired with oz per foot, or meters are paired with g per meter.

Frequently asked questions