R-Pro › Field cases › VRF systems
VRF Additional Refrigerant Charging — g/m by Pipe Length
Likely causes
Calculate additional charge + precision weighed charge
Check: Additional charge = g/m by liquid pipe diameter × (total liquid pipe length − standard free length). Free length typically 30 m (manual prevails). Liquid 6.35 mm = 20 g/m, 9.52 = 50, 12.7 = 110, 15.88 = 170, 19.05 = 250 (R-410A; R-32 slight variance). Precision digital scale 0.1 g resolution.
What to do: Weigh cylinder with precision digital scale (0.1 g, A2L-rated). With system OFF, charge as liquid through high-side service port. Stop immediately at calculated amount. Fill out charging record and affix to side of outdoor unit. Verify charge via superheat/subcooling at commissioning.
Wrong VRF charge = 30%+ capacity loss systemwide. Document charging record and post on equipment. Future leak = uses this as baseline. Use a single cylinder model — don't swap mid-charge (label confusion).
All 565 cases work offline in R-Pro, with error codes for 62 brands and P-T data for 108 refrigerants.
Open R-Pro →Related cases
- EEV Stuck — Reduced Cooling/Heating Capacity
- Indoor Unit Drain Pump Malfunction Causing Water Leak
- Indoor Unit Fan Abnormal Noise and Vibration
- Remote Control Reception Failure — Commands Not Transmitted
- Horizontal Indoor Unit Airflow Louver Malfunction
- P/Q Communication Wire Open/Short Circuit — Indoor Unit Communication Error