Product Information GCS 16 Heat Pump: 2 to 5 Ton From 2 to 5 and 15 & 20 Nominal Tons 1- & 2-Stage Heating / 1- & 2-Stage Cooling 80% AFUE / 9.00 EER Efficiency (2 to 5 Ton / 10 SEER) Aluminized Steel, Tubular Heat Exchanger Multiple Refrigeration Circuits (on 2-Stage Units) Complete Line of Accessories 1-Year Limited Warranty on All Parts 10-Year Limited Heat Exchanger Warranty 5-Year Limited Compressor Warranty