how is lennox air conditioner rated?
Lennox makes the most efficient split system available right now, the Signature Series Lennox XC25 with a 26 SEER rating. It also makes the most efficient two-stage split system air conditioner, the Elite Series Lennox XC20 with a 20 SEER rating, and the most efficient single-stage AC, the 18.5 SEER Lennox SL18XC1.