Scroll chillers are available from 100 tons to 350 tons and can be air cooled or water cooled; however they are less efficient than Screw Type chillers. Scroll compressors cannot be repaired and so upon failure, they are required to be replaced. Scroll chillers are less expensive than Screw types and are not designed to work with VFDs. The load on scroll chiller is controlled by Hot Gas Bypass. The common refrigerant in Scroll chillers is R-410 (HFC-410A).