Air-source heat pumps
Ducted central systems that both heat and cool using a refrigerant cycle.
Buyer's guide: Cold-climate heat pumps: what actually mattersWe hold full sourced data on 10 air-source heat pumps, each with a specification traced to its source and cross-checked against owner reports.
Daikin Fit AuroraDH9VS
Side-discharge variable-speed heat pump with a small footprint, rated for cold-climate operation to -13°F.
Owners: 1 good3 mixed 5 reports →Rheem Endeavor Line Prestige RP19AYRP19AY48
Rheem's current inverter-driven variable-speed heat pump on the new R-454B refrigerant, and an open 24V system that works with any thermostat.
Fujitsu Airstage Ducted J-seriesAOUH36KUAS1
Fujitsu's ducted single-zone inverter heat pump on R-32 refrigerant, rated to -5°F, an open 24V system.
Bosch IDS Ultra
Variable-speed ducted heat pump that undercuts the premium American brands on price while matching most of their cold-weather capability.
Owners: 1 good1 watch-out1 mixed 3 reports →Lennox SL25XPVSL25XPV-048
Lennox's flagship variable-capacity ducted heat pump, among the highest SEER2 in the class, but locked to the iComfort communicating thermostat.
Bryant Evolution Extreme 284ANV284ANV024
Bryant's variable-speed cold-climate heat pump (Carrier Infinity's sibling), with a deep 4:1 turndown — the class's best published modulation.
Carrier Infinity 2425VNA4
Carrier's flagship variable-speed ducted heat pump, and one of very few conventional split systems that holds full heating capacity down to 0°F.
Owners: 2 watch-out1 mixed 3 reports →Trane 19 Multi-Speed Low Profile
Low-profile cold-climate heat pump designed for installations where cabinet height is constrained.
Owners: 1 good2 watch-out 3 reports →Mitsubishi M-Series SUZ-NLHZSUZ-AK36NLHZ
Mitsubishi's ducted Hyper-Heating outdoor unit, pairable with a conventional air handler for whole-house ducted retrofit.
Owners: 3 good1 mixed 5 reports →Mitsubishi P-series PUZ-AK Hyper-HeatPUZ-AK48NLHZ
Mitsubishi's 4-ton ducted Hyper-Heat system on R-454B — the best-documented cold-climate performer in this set, NEEP-listed with a full 5°F dataset.
What the specifications mean
HSPF2
Heating Seasonal Performance Factor 2 -- heating output in BTU divided by watt-hours consumed across a heating season.
The headline heating efficiency number, but it is calculated for a moderate climate (DOE Region IV). If you live somewhere genuinely cold, HSPF2 flatters equipment that falls apart below freezing. Use COP at 5F instead.
SEER2
Seasonal Energy Efficiency Ratio 2 -- cooling output over a season divided by electricity used, measured under the 2023 DOE test procedure.
The headline cooling efficiency number. SEER2 replaced SEER in 2023 and uses a higher external static pressure, so SEER2 figures run roughly 4-5% lower than the old SEER for the same equipment. Never compare a SEER number to a SEER2 number.
Capacity retained at 5°F (%)
Heating capacity at 5°F expressed as a percentage of rated capacity at 47°F.
This is the field that separates a real cold-climate heat pump from a badged one. A conventional heat pump may retain only 50-60% of capacity at 5F, meaning backup heat carries the house on cold nights. The best cold-climate units hold 100% or more.
Minimum operating temperature (°F)
The lowest outdoor temperature at which the manufacturer rates the unit to produce heat.
Below this temperature the compressor stops and backup heat takes over entirely. Compare against your area's 99% winter design temperature.
Durability is read from objective signals only — the weakest link in the warranty, the refrigerant's service outlook, and what trade and owner reports say about parts and service. How we research → · Comparing whole system types, not just this category? Run the recommender →