HVAC
HVAC Refrigerant Charge Calculator
Estimate the refrigerant a split system holds once the line set length is accounted for.
Result
An estimate for ordering and planning only. The final charge is set by measurement, using superheat on a fixed-orifice system or subcooling on a TXV system, against the manufacturer's chart for that model. Charging by weight alone, or by pressure alone, is how systems end up over or undercharged.
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About this calculator
Can I just charge to the calculated weight?
Only as a starting point on a fully evacuated new system, and even then it is verified by superheat or subcooling afterwards. The nameplate and the manufacturer's data are the authority, not this figure.
Why does line length change the charge?
The liquid line holds refrigerant. A longer run holds more, so the system needs additional charge to fill it without starving the evaporator.
Does the suction line need adding too?
It holds vapour, which weighs very little, so it is normally ignored. The liquid line is what matters.
The formula
total = factory charge + (line length - included length) x ounces per foot / 16
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Estimating is the easy part
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