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	63% (higher)median —	34% (higher)median —
COP at 5°F	64% (higher)median 2.10	34% (higher)median 1.80
Capacity retention at 5°F	61% (higher)median 75%	33% (higher)median 72%
HSPF2	74% (higher)median 10.0	46% (higher)median 9.5
SEER2	62% (higher)median 19.4	36% (higher)median 20.0
EER2	59% (higher)median 12.0	26% (higher)median 10.5
Heating capacity at 5°F	62% (higher)median 19,000 Btu/h	40% (higher)median 9,500 Btu/h
Outdoor models	37	37
AHRI certifications	121	37

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)	86.5%32 models	67.6%25 models
CEE 2026 Tier 1 (Split ASHP)	83.8%31 models	67.6%25 models
CEE Advanced Tier (Split ASHP)	2.7%1 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	81.1%30 models	56.8%21 models
DOE Cold Climate Heat Pump Challenge	2.7%1 models	0%0 models
ENERGY STAR Cold Climate	83.8%31 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 · 4 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	9 · index 80%	None
Ducted, 2 tons	5 · index 73%	None
Ducted, 2.5–3 tons	7 · index 67%	None
Ducted, 3.5–4.5 tons	7 · index 63%	None
Ducted, 5 tons and up	1 · index 63%	None
Non-ducted, up to 1.5 tons	16 · index 58%	27 · index 31%
Non-ducted, 2 tons	4 · index 53%	3 · index 35%
Non-ducted, 2.5–3 tons	4 · index 54%	6 · index 52%
Non-ducted, 3.5–4.5 tons	3 · index 57%	1 · index 27%
Non-ducted, 5 tons and up	1 · index 27%	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	93.5(50 is the typical model of its size class)WOS-06PRE/230with ducted air handler WIDL-06MOC/2309 of 9 models qualify · AHRI 215864077	No models in this size class
Ducted, 2 tons	85.7(50 is the typical model of its size class)WOS-24PRE/230with ducted air handler WIDH-24MOC/2305 of 5 models qualify · AHRI 215864084	No models in this size class
Ducted, 2.5–3 tons	82.5(50 is the typical model of its size class)WOM-36HH5/2307 of 7 models qualify · AHRI 215864112	No models in this size class
Ducted, 3.5–4.5 tons	82.7(50 is the typical model of its size class)WOM-48HH6/2307 of 7 models qualify · AHRI 215864115	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	94.4(50 is the typical model of its size class) (higher)WOS-06PRE/230with ductless indoor unit WI1C-06MOC/23011 of 16 models qualify · AHRI 215864073	68.6(50 is the typical model of its size class)TMSC-18HA2/I2XI20B-OAlso listed as TMSC-18HA2/I2XI20B-O14 of 27 models qualify · AHRI 216020699
Non-ducted, 2 tons	89.4(50 is the typical model of its size class)WOS-24PRE/230with ductless indoor unit WI4C-24MOC/2304 of 4 models qualify · AHRI 215864072	None on this board (0 of 3 models qualify)
Non-ducted, 2.5–3 tons	72.6(50 is the typical model of its size class) (higher)WOM-36HH5/2304 of 4 models qualify · AHRI 215864113	57.5(50 is the typical model of its size class)TMSC-27HA2/I2XI19B-OAlso listed as TMSC-27HA2/I2XI19B-O6 of 6 models qualify · AHRI 216020700
Non-ducted, 3.5–4.5 tons	69.9(50 is the typical model of its size class) (higher)WOM-60HH6/2303 of 3 models qualify · AHRI 215864119	24.7(50 is the typical model of its size class)ZP42M2/19-O1 of 1 models qualify · AHRI 218035871
Non-ducted, 5 tons and up	None on this board (0 of 1 models qualify)	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	95.0(50 is the typical model of its size class)WOS-06PRE/230with ducted air handler WIDL-06MOC/2309 of 9 models have all five ratings · AHRI 215864077	No models in this size class
Ducted, 2 tons	79.6(50 is the typical model of its size class)WDHP-2436T-Gwith ducted air handler WDAH-24MOC-G5 of 5 models have all five ratings · AHRI 217048501	No models in this size class
Ducted, 2.5–3 tons	83.6(50 is the typical model of its size class)WOM-36HH5/2307 of 7 models have all five ratings · AHRI 215864112	No models in this size class
Ducted, 3.5–4.5 tons	85.1(50 is the typical model of its size class)WOM-48RH6/2307 of 7 models have all five ratings · AHRI 215864100	No models in this size class
Ducted, 5 tons and up	62.5(50 is the typical model of its size class)WOM-60RH6/2301 of 1 models have all five ratings · AHRI 215864103	No models in this size class
Non-ducted, up to 1.5 tons	93.8(50 is the typical model of its size class) (higher)WOS-06PRE/230with ductless indoor unit WIHW-06MOC/23016 of 16 models have all five ratings · AHRI 215864044	72.2(50 is the typical model of its size class)TMSC-18HA2/I2XI20B-OAlso listed as TMSC-18HA2/I2XI20B-O27 of 27 models have all five ratings · AHRI 216020699
Non-ducted, 2 tons	74.3(50 is the typical model of its size class) (higher)WOS-24QUA/230with ductless indoor unit WIHW-24MOC/2304 of 4 models have all five ratings · AHRI 215864043	39.1(50 is the typical model of its size class)TSC-24HA2/I2XI18B-Owith ductless indoor unit TSC-24HA2/I2XI18B-IAlso listed as TSC-24HA2/I2XI18B-O3 of 3 models have all five ratings · AHRI 216020695
Non-ducted, 2.5–3 tons	66.3(50 is the typical model of its size class) (higher)WOM-36HH5/2304 of 4 models have all five ratings · AHRI 215864111	65.1(50 is the typical model of its size class)TMSC-27HA2/I2XI19B-OAlso listed as TMSC-27HA2/I2XI19B-O6 of 6 models have all five ratings · AHRI 216020700
Non-ducted, 3.5–4.5 tons	62.6(50 is the typical model of its size class) (higher)WOM-60HH6/2303 of 3 models have all five ratings · AHRI 215864117	27.2(50 is the typical model of its size class)ZP42M2/19-O1 of 1 models have all five ratings · AHRI 218035871
Non-ducted, 5 tons and up	32.5(50 is the typical model of its size class)WOM-60RH6/2301 of 1 models have all five ratings · AHRI 215864102	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 99% · 2.51WOS-12QUA/230Non-ducted, up to 1.5 tons	beats 71% · 2.10TSC-24HA2/I2XI18B-OAlso listed as TSC-24HA2/I2XI18B-ONon-ducted, 2 tons
Capacity retention at 5°F	beats 98% · 126%WOS-09PRE/230Non-ducted, up to 1.5 tons	beats 61% · 80%TMSC-18HA2/I2XI20B-OAlso listed as TMSC-18HA2/I2XI20B-ONon-ducted, up to 1.5 tons
HSPF2	beats 99% · 11.0WOM-48HH6/230Ducted, 3.5–4.5 tons	beats 80% · 10.5TMSC-27HA2/I2XI19B-OAlso listed as TMSC-27HA2/I2XI19B-ONon-ducted, 2.5–3 tons
SEER2	beats 96% · 20.4WOM-48RH6/230Ducted, 3.5–4.5 tons	beats 91% · 24.0TMSC-27HA2/I2XI19B-OAlso listed as TMSC-27HA2/I2XI19B-ONon-ducted, 2.5–3 tons
EER2	beats 99% · 14.4WOS-06PRE/230Ducted, up to 1.5 tons	beats 70% · 13.0TMSC-18HA2/I2XI20B-OAlso listed as TMSC-18HA2/I2XI20B-ONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 97% · 39,000 Btu/hWDHP-36HHDucted, 2.5–3 tons	beats 88% · 16,000 Btu/hTMSC-18HA2/I2XI20B-OAlso listed as TMSC-18HA2/I2XI20B-ONon-ducted, up to 1.5 tons

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Wells vs ZOKOP heat pumps