Lennox Heat Pumps SL25XPVUp to 24 SEERUp to 23 SEER2Up to 11.8 HSPFUp to 10.3 HSPF2 EL18XPVUp to 20 SEERUp to 10 HSPF EL22XPVUp to 23 SEERUp to 22 SEER2Up to 10 HSPFUp to 9.5 HSPF2 EL17XP1Up to 18.6 SEERUp to 17 SEER2Up to 10.6 HSPFUp to 8.5 HSPF2 ML17XP1Up to 18.6 SEERUp to 14.3 SEER2Up to 10.6 HSPFUp to 7.5 HSPF2