A scroll compressor uses two interleaved spiral-shaped scrolls to compress refrigerant — one scroll is fixed and one orbits around it, progressively reducing the volume of refrigerant gas pockets as they spiral toward the center outlet. This design makes scroll compressors the dominant type in modern residential HVAC equipment.
Advantages of scroll compressors include: fewer moving parts than reciprocating compressors (lower maintenance), quieter and smoother operation, higher efficiency, better tolerance of liquid refrigerant slugs, and compact design. Modern two-stage and variable-speed (inverter-driven) scroll compressors allow for capacity modulation.
Scroll compressors are directional — they must rotate in the correct direction or they will not compress and can be damaged. Proper wiring sequence on three-phase applications is critical. They are sealed units that cannot be repaired in the field — a failed scroll compressor requires complete replacement.