The R Series(tm) central chillers use rotational compression technology with up to 50% fewer moving parts than reciprocating compressors. In sizes from 30 to 100 ton capacity, the chillers use hermetically sealed scroll compressors. Semi-hermetically sealed screw compressors are used in systems sizes from 54 to 195 tons. Up to 100 tons, both styles of compressors are matched to brazed plate evaporators. From 115 to 195 tons, they match to shell and tube evaporators. All scroll compressors use R-22 refrigerant while all screw compressors use R-134a, a non-CFC refrigerant providing energy efficiency increases of up to 12%.