Against comparable models

Each cell is the share of same-size, same-type models that the manufacturer’s typical model beats (50% is typical); the higher score is in bold. Raw medians are underneath for context: they depend on which sizes each one makes, so they are not compared.

Wells and ZOKOP on every ratingPeer scores, 0–100 · grey ticks: every ranked manufacturer · shaded: the middle half of each one’s modelsMeasured against models of the same size and duct type, Wells scores higher on 6 of the 6 ratings.

Wells
ZOKOP
Other ranked manufacturers

Source: AHRI Directory, NEEP · as of Oct 9, 2026

Average peer percentile, raw median and rank among ranked manufacturers
Rating	Wells	ZOKOP
Efficiency index	57% (higher)median —	34% (higher)median —
COP at 5°F	40% (higher)median 1.85	22% (higher)median 1.80
Capacity retention at 5°F	60% (higher)median 79%	35% (higher)median 68%
HSPF2	70% (higher)median 9.5	18% (higher)median 8.5
SEER2	65% (higher)median 20.2	32% (higher)median 19.0
EER2	50% (higher)median 11.0	24% (higher)median 10.0
Heating capacity at 5°F	59% (higher)median 23,000 Btu/h	44% (higher)median 10,350 Btu/h
Outdoor models	35	17
AHRI certifications	70	17

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	Wells	ZOKOP
CEE 2025 Tier 1 (Split ASHP)	74.3%26 models	41.2%7 models
CEE 2026 Tier 1 (Split ASHP)	68.6%24 models	41.2%7 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	60%21 models	29.4%5 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	60%21 models	0%0 models

Sizes and duct types offered

Models in each peer group, with the efficiency index of those models against the rest of the group.

Side by side, inside each size and duct typeShape: every model of the group · bars: each manufacturer’s middle half, median dot, 10th–90th line · 3 groups where both have models

Wells
ZOKOP
All models of the group

Raw ratings are only placed side by side within one size and duct type, where they are comparable.

Source: AHRI Directory · as of Oct 9, 2026

Models per peer group · efficiency index within the group
Size and duct type	Wells	ZOKOP
Ducted, up to 1.5 tons	2 · index 59%	None
Ducted, 2 tons	1 · index 53%	None
Ducted, 2.5–3 tons	9 · index 62%	None
Ducted, 3.5–4.5 tons	8 · index 58%	None
Ducted, 5 tons and up	1 · index 57%	None
Non-ducted, up to 1.5 tons	11 · index 56%	15 · index 35%
Non-ducted, 2 tons	2 · index 49%	1 · index —
Non-ducted, 2.5–3 tons	7 · index 57%	1 · index 28%
Non-ducted, 3.5–4.5 tons	4 · index 51%	None

Cold-climate and all-around picks, size class by size class

Each manufacturer’s best model on each board in every size and duct type, side by side; the higher score is in bold. Both scores are 0–100 against every model of that size class (the line on each bar is 50, the typical model there), so the two compare fairly even when they make different sizes.

Cold-climate picks

Best cold-climate pick per size and duct type (keeps at least 70% of its heat at 5°F). Qualifies when its capacity retention at 5°F (capacity at 5°F as a share of capacity at 47°F) is at least 70% and Capacity retention at 5°F, COP at 5°F, HSPF2 are all rated. Score = the equal-weight mean of its peer percentiles on Capacity retention at 5°F, COP at 5°F, HSPF2 (share of the other models in its peer group it beats, 0–100), all from one certified pairing: in each duct type a model is sold in, its qualifying pairing of that type with the best score; equal scores (one decimal) go to the higher heating capacity at 5°F.
Size and duct type	WellsCold-climate score, best model	ZOKOPCold-climate score, best model
Ducted, up to 1.5 tons	52.0(50 is the typical model of its size class)WMMA-18HFMO2 of 2 models qualify · AHRI 213286761	No models in this size class
Ducted, 2 tons	66.5(50 is the typical model of its size class)WUCA-24HFMOwith ducted air handler WUA-24HFMAH1 of 1 models qualify · AHRI 213307899	No models in this size class
Ducted, 2.5–3 tons	80.4(50 is the typical model of its size class)WMCA-27HFMO7 of 9 models qualify · AHRI 213286779	No models in this size class
Ducted, 3.5–4.5 tons	74.9(50 is the typical model of its size class)WMCA-48HFMO5 of 8 models qualify · AHRI 213286782	No models in this size class
Ducted, 5 tons and up	None on this board (0 of 1 models qualify)	No models in this size class
Non-ducted, up to 1.5 tons	74.8(50 is the typical model of its size class) (higher)WSA-09HFMOwith ductless indoor unit WSA-09HFMI7 of 11 models qualify · AHRI 214421469	47.5(50 is the typical model of its size class)TSC-12HA2/I3XI23-Owith ductless indoor unit TSC-12HA2/I3XI23-I5 of 15 models qualify · AHRI 213927374
Non-ducted, 2 tons	61.1(50 is the typical model of its size class)WSA-24HFMOwith ductless indoor unit WSA-24HFMI1 of 2 models qualify · AHRI 214421472	None on this board (0 of 1 models qualify)
Non-ducted, 2.5–3 tons	87.0(50 is the typical model of its size class)WMCA-36HFMO4 of 7 models qualify · AHRI 213307896	None on this board (0 of 1 models qualify)
Non-ducted, 3.5–4.5 tons	80.5(50 is the typical model of its size class)WMCA-48HFMO2 of 4 models qualify · AHRI 213286781	No models in this size class

All-around best

Best all-around model per size and duct type. Score = 50% heating, the mean of its peer percentiles on COP at 5°F, Capacity retention at 5°F, HSPF2, plus 50% cooling, the mean of its peer percentiles on SEER2 and EER2 (share of the other models in its peer group it beats, 0–100). All five ratings are required; there is no minimum heat kept at 5°F. In each duct type a model is sold in, it is scored on its pairing of that type with the best score; equal scores (one decimal) go to the higher cold-climate score, then the higher heating capacity at 5°F.
Size and duct type	WellsAll-around score, best model	ZOKOPAll-around score, best model
Ducted, up to 1.5 tons	59.4(50 is the typical model of its size class)WMMA-18HFMO2 of 2 models have all five ratings · AHRI 213286761	No models in this size class
Ducted, 2 tons	65.8(50 is the typical model of its size class)WUCA-24HFMOwith ducted air handler WUA-24HFMAH1 of 1 models have all five ratings · AHRI 213307899	No models in this size class
Ducted, 2.5–3 tons	83.7(50 is the typical model of its size class)WMCA-36HFMO9 of 9 models have all five ratings · AHRI 213307897	No models in this size class
Ducted, 3.5–4.5 tons	82.0(50 is the typical model of its size class)WMCA-48HFMO8 of 8 models have all five ratings · AHRI 213286782	No models in this size class
Ducted, 5 tons and up	57.1(50 is the typical model of its size class)WSMA-60HFMOwith ducted air handler WSMA-60HFMD1 of 1 models have all five ratings · AHRI 214797744	No models in this size class
Non-ducted, up to 1.5 tons	84.4(50 is the typical model of its size class) (higher)WSA-09HFMOwith ductless indoor unit WSA-09HFMI11 of 11 models have all five ratings · AHRI 214421469	60.2(50 is the typical model of its size class)TSC-12HA2/I3XI23-Owith ductless indoor unit TSC-12HA2/I3XI23-I9 of 15 models have all five ratings · AHRI 213927374
Non-ducted, 2 tons	70.7(50 is the typical model of its size class)WSA-24HFMOwith ductless indoor unit WSA-24HFMI2 of 2 models have all five ratings · AHRI 214421472	None on this board (0 of 1 models have all five ratings)
Non-ducted, 2.5–3 tons	76.8(50 is the typical model of its size class) (higher)WMCA-36HFMO7 of 7 models have all five ratings · AHRI 213307896	28.1(50 is the typical model of its size class)TMSC-27HA2/I2XI19-O1 of 1 models have all five ratings · AHRI 213927380
Non-ducted, 3.5–4.5 tons	73.8(50 is the typical model of its size class)WMCA-48HFMO4 of 4 models have all five ratings · AHRI 213286781	No models in this size class

All-around board, every manufacturer

Standout model on each rating

Each manufacturer’s model that beats the largest share of comparable models on the rating; the higher share is in bold.

Top model per rating by peer percentile, with its AHRI-certified value and peer group
Rating	Wells	ZOKOP
COP at 5°F	beats 83% · 2.16WSB-09HFBONon-ducted, up to 1.5 tons	beats 22% · 1.80TSC-18HA2/I2XI19-ONon-ducted, up to 1.5 tons
Capacity retention at 5°F	beats 96% · 101%WMCA-27HFMODucted, 2.5–3 tons	beats 60% · 76%TSC-12HA2/I3XI23-ONon-ducted, up to 1.5 tons
HSPF2	beats 97% · 10.9WMCA-36HFMONon-ducted, 2.5–3 tons	beats 57% · 9.5TSC-12HA2/I3XI23-ONon-ducted, up to 1.5 tons
SEER2	beats 99% · 20.9WMCA-48HFMODucted, 3.5–4.5 tons	beats 73% · 23.0TSC-09HA1/I3XI22-ONon-ducted, up to 1.5 tons
EER2	beats 95% · 15.8WSA-09HFMONon-ducted, up to 1.5 tons	beats 68% · 13.0TSC-12HA2/I3XI23-ONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 96% · 20,000 Btu/hWMCA-18HFMONon-ducted, up to 1.5 tons	beats 78% · 13,000 Btu/hTMSC-18HA2/I2XI20-ONon-ducted, up to 1.5 tons

More comparisons

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Wells vs ZOKOP heat pumps