On a new install or a system that has been recovered and evacuated, weighing in the full charge is the most accurate starting point: nameplate charge, plus or minus the adjustment for line set length. The tech then confirms with superheat or subcooling once the system runs at stable conditions. Blends are weighed in as liquid so the mix stays correct.
Weigh in 7 pounds 4 ounces, that's nameplate plus the 30 foot line, then we'll check subcooling at full load.
Also heard as
- weigh in the charge
- charge by weight
- weighed in
Related terms
Line set
The pair of copper refrigerant lines, one insulated suction line and one smaller liquid line, linking indoor and outdoor units.
Subcooling
How many degrees liquid refrigerant is below its condensing temperature at the same pressure.
Pull a vacuum
To evacuate a refrigeration system with a vacuum pump, removing air and moisture before charging.
Top off
To add refrigerant to a system that is low on charge without finding and fixing the leak.