The Tranquility 20 Single-Stage (TS) Series builds on ClimateMaster’s commitment to utilizing the most advanced technology and design to create one of the most efficient single-stage water-source heat pump available today. The Tranquility 20 Single-Stage Series combines EarthPure® (HFC-410A) refrigerant with the Copeland Scroll compressor (size 018 and above) and either an ECM variable speed or PSC multi-speed fan motor to create unmatched performance and flexibility.