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.

TK'S and WILLIS 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, TK'S and WILLIS split the 6 ratings 3–3.

TK'S
WILLIS
Other ranked manufacturers

Source: AHRI Directory, NEEP · as of Oct 11, 2026

Average peer percentile, raw median and rank among ranked manufacturers
Rating	TK'S	WILLIS
Efficiency index	48%median —	51%median —
COP at 5°F	34%median 1.83	39%median 1.84
Capacity retention at 5°F	31%median 65%	64%median 76%
HSPF2	58% (higher)median 9.1	52% (higher)median 9.0
SEER2	64% (higher)median 21.1	55% (higher)median 21.0
EER2	47% (higher)median 10.8	46% (higher)median 12.0
Heating capacity at 5°F	38%median 12,600 Btu/h	68%median 13,600 Btu/h
Outdoor models	15	15
AHRI certifications	29	29

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	TK'S	WILLIS
CEE 2025 Tier 1 (Split ASHP)	66.7%10 models	86.7%13 models
CEE 2026 Tier 1 (Split ASHP)	46.7%7 models	80%12 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	20%3 models	86.7%13 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	0%0 models	73.3%11 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 · 6 groups where both have models

TK'S
WILLIS
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 11, 2026

Models per peer group · efficiency index within the group
Size and duct type	TK'S	WILLIS
Ducted, up to 1.5 tons	2 · index 59%	1 · index 32%
Ducted, 2.5–3 tons	3 · index 62%	4 · index 51%
Ducted, 3.5–4.5 tons	2 · index 64%	2 · index 55%
Ducted, 2 tons	None	1 · index 46%
Non-ducted, up to 1.5 tons	8 · index 40%	8 · index 44%
Non-ducted, 2 tons	1 · index 16%	1 · index 72%
Non-ducted, 2.5–3 tons	4 · index 50%	3 · index 68%
Non-ducted, 3.5–4.5 tons	2 · index 48%	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	TK'SCold-climate score, best model	WILLISCold-climate score, best model
Ducted, up to 1.5 tons	52.0(50 is the typical model of its size class) (higher)T2C-18HFN1Also listed as T2C-18HFN12 of 2 models qualify · AHRI 207742406	36.0(50 is the typical model of its size class)MZUHW18KCH21S2-O1 of 1 models qualify · AHRI 214810334
Ducted, 2 tons	No models in this size class	50.1(50 is the typical model of its size class)MZUHW24KCH21S2-O1 of 1 models qualify · AHRI 214810335
Ducted, 2.5–3 tons	57.4(50 is the typical model of its size class) (higher)T3C-30HFN1*1 of 3 models qualify · AHRI 212528010	55.3(50 is the typical model of its size class)FLEX24/36KUHwith ducted air handler FLEXAH24/36K4 of 4 models qualify · AHRI 214137765
Ducted, 3.5–4.5 tons	None on this board (0 of 2 models qualify)	56.7(50 is the typical model of its size class)FLEX48/60KUHwith ducted air handler FLEXAH48/60K2 of 2 models qualify · AHRI 214797686
Non-ducted, up to 1.5 tons	None on this board (0 of 8 models qualify)	73.5(50 is the typical model of its size class)MZUHW18KCH21S2-O7 of 8 models qualify · AHRI 214810331
Non-ducted, 2 tons	None on this board (0 of 1 models qualify)	76.1(50 is the typical model of its size class)MZUHW24KCH21S2-O1 of 1 models qualify · AHRI 214810332
Non-ducted, 2.5–3 tons	49.3(50 is the typical model of its size class)T3C-30HFN1*1 of 4 models qualify · AHRI 212528009	73.7(50 is the typical model of its size class) (higher)MZUHW42KCH21S2-O3 of 3 models qualify · AHRI 214810330
Non-ducted, 3.5–4.5 tons	None on this board (0 of 2 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	TK'SAll-around score, best model	WILLISAll-around score, best model
Ducted, up to 1.5 tons	59.4(50 is the typical model of its size class) (higher)T2C-18HFN1Also listed as T2C-18HFN12 of 2 models have all five ratings · AHRI 207742406	31.5(50 is the typical model of its size class)MZUHW18KCH21S2-O1 of 1 models have all five ratings · AHRI 214810334
Ducted, 2 tons	No models in this size class	45.9(50 is the typical model of its size class)MZUHW24KCH21S2-O1 of 1 models have all five ratings · AHRI 214810335
Ducted, 2.5–3 tons	71.5(50 is the typical model of its size class) (higher)T3C-30HFN1*3 of 3 models have all five ratings · AHRI 212528010	53.1(50 is the typical model of its size class)MZUHW30KCH21S2-O4 of 4 models have all five ratings · AHRI 214810336
Ducted, 3.5–4.5 tons	63.5(50 is the typical model of its size class) (higher)T5C-48HFN1Also listed as T5C-48HFN12 of 2 models have all five ratings · AHRI 207742412	57.4(50 is the typical model of its size class)PRT60KUH2 of 2 models have all five ratings · AHRI 214137764
Non-ducted, up to 1.5 tons	52.0(50 is the typical model of its size class)T2C-18HFN1Also listed as T2C-18HFN18 of 8 models have all five ratings · AHRI 207742405	63.8(50 is the typical model of its size class) (higher)HW12KUHR410A-Owith ductless indoor unit HW12KUHR410A-I8 of 8 models have all five ratings · AHRI 216772615
Non-ducted, 2 tons	15.9(50 is the typical model of its size class)TWS-24HRDN1with ductless indoor unit TWS-24HRDN11 of 1 models have all five ratings · AHRI 205807089	71.5(50 is the typical model of its size class) (higher)MZUHW24KCH21S2-O1 of 1 models have all five ratings · AHRI 214810332
Non-ducted, 2.5–3 tons	66.7(50 is the typical model of its size class)T3C-30HFN1*4 of 4 models have all five ratings · AHRI 212528009	70.2(50 is the typical model of its size class) (higher)MZUHW42KCH21S2-O3 of 3 models have all five ratings · AHRI 214810330
Non-ducted, 3.5–4.5 tons	48.3(50 is the typical model of its size class)T5C-48HFN1Also listed as T5C-48HFN12 of 2 models have all five ratings · AHRI 207742411	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	TK'S	WILLIS
COP at 5°F	beats 86% · 2.18TWS-18HRDN1Non-ducted, up to 1.5 tons	beats 90% · 2.23MZUHW18KCH21S2-ONon-ducted, up to 1.5 tons
Capacity retention at 5°F	beats 55% · 71%T3C-30HFN1*Ducted, 2.5–3 tons	beats 85% · 89%MZUHW30KCH21S2-ODucted, 2.5–3 tons
HSPF2	beats 95% · 9.7T5C-48HFN1Also listed as T5C-48HFN1Ducted, 3.5–4.5 tons	beats 82% · 10.0MZUHW36KCH21S2-ONon-ducted, 2.5–3 tons
SEER2	beats 98% · 21.0T3C-30HFN1*Ducted, 2.5–3 tons	beats 83% · 24.0PUHW12KCH24S2-ONon-ducted, up to 1.5 tons
EER2	beats 75% · 12.2T3C-30HFN1*Non-ducted, 2.5–3 tons	beats 84% · 12.5MZUHW30KCH21S2-ONon-ducted, 2.5–3 tons
Heating capacity at 5°F	beats 75% · 12,900 Btu/hT2C-18HFN1Also listed as T2C-18HFN1Non-ducted, up to 1.5 tons	beats 84% · 13,800 Btu/hMZUHW18KCH21S2-ONon-ducted, up to 1.5 tons

More comparisons

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TK'S vs WILLIS heat pumps