ATK vs WINDAIR heat pumps

Measured against models of the same size and duct type, ATK scores higher on 5 of the 6 ratings. ATK has 13 outdoor models, WINDAIR has 13 outdoor models. ATK and WINDAIR have no QMID on file and are not ranked.

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CompareData as of Oct 11, 2026updated Oct 11, 2026 · sources

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.

ATK and WINDAIR 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, ATK scores higher on 5 of the 6 ratings.

ATK
WINDAIR
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	ATK	WINDAIR
Efficiency index	47%median —	65%median —
COP at 5°F	51% (higher)median 1.91	36% (higher)median 1.80
Capacity retention at 5°F	57% (higher)median 79%	44% (higher)median 70%
HSPF2	75% (higher)median 9.4	27% (higher)median 8.5
SEER2	44% (higher)median 15.5	37% (higher)median 18.5
EER2	20%median 10.0	50%median 11.1
Heating capacity at 5°F	64% (higher)median 27,000 Btu/h	40% (higher)median 8,400 Btu/h
Outdoor models	13	13
AHRI certifications	24	13

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	ATK	WINDAIR
CEE 2025 Tier 1 (Split ASHP)	53.8%7 models	23.1%3 models
CEE 2026 Tier 1 (Split ASHP)	38.5%5 models	23.1%3 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	46.2%6 models	15.4%2 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	0%0 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 · 0 groups where both have models

ATK
WINDAIR
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	ATK	WINDAIR
Ducted, up to 1.5 tons	2 · index 43%	None
Ducted, 2 tons	2 · index 49%	None
Ducted, 2.5–3 tons	5 · index 45%	None
Ducted, 3.5–4.5 tons	4 · index 50%	None
Non-ducted, up to 1.5 tons	None	10 · index 65%
Non-ducted, 2 tons	None	2 · index —
Non-ducted, 2.5–3 tons	None	1 · index —

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	ATKCold-climate score, best model	WINDAIRCold-climate score, best model
Ducted, up to 1.5 tons	64.3(50 is the typical model of its size class)ACI-AUO18SHP-Mwith ducted air handler ACI-BCO24CP171 of 2 models qualify · AHRI 212386850	No models in this size class
Ducted, 2 tons	69.5(50 is the typical model of its size class)ACI-AUO24SHP-Mwith ducted air handler ACI-AUI24VHE2 of 2 models qualify · AHRI 212386849	No models in this size class
Ducted, 2.5–3 tons	78.6(50 is the typical model of its size class)ACI-AUO36SHP-Mwith ducted air handler ACI-CCO36CP213 of 5 models qualify · AHRI 212386847	No models in this size class
Ducted, 3.5–4.5 tons	73.8(50 is the typical model of its size class)ACI-AUO48SHP-Mwith ducted air handler ACI-AUI48VHE2 of 4 models qualify · AHRI 212386843	No models in this size class
Non-ducted, up to 1.5 tons	No models in this size class	75.0(50 is the typical model of its size class)DWH09UW3SXETE00/Owith ductless indoor unit DWH09UW3SXETE00/I2 of 10 models qualify · AHRI 202021941
Non-ducted, 2 tons	No models in this size class	None on this board (0 of 2 models qualify)
Non-ducted, 2.5–3 tons	No models in this size class	None on this board (0 of 1 models qualify)

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	ATKAll-around score, best model	WINDAIRAll-around score, best model
Ducted, up to 1.5 tons	51.9(50 is the typical model of its size class)ACI-AUO18SHP-Mwith ducted air handler ACI-BCO24CP172 of 2 models have all five ratings · AHRI 212386850	No models in this size class
Ducted, 2 tons	67.3(50 is the typical model of its size class)ACI-AUO24SHP-Mwith ducted air handler ACI-AUI24VHE2 of 2 models have all five ratings · AHRI 212386849	No models in this size class
Ducted, 2.5–3 tons	57.8(50 is the typical model of its size class)ACI-AUO36SHP-Mwith ducted air handler ACI-AUI36VHE5 of 5 models have all five ratings · AHRI 212386845	No models in this size class
Ducted, 3.5–4.5 tons	53.3(50 is the typical model of its size class)ACI-AUO60SHP-Mwith ducted air handler ACI-AUI60VHE3 of 3 models have all five ratings · AHRI 212386842	No models in this size class
Ducted, 5 tons and up	45.6(50 is the typical model of its size class)ACI-SDAUO60SHPwith ducted air handler ACI-AUI60VHE1 of 1 models have all five ratings · AHRI 213430648	No models in this size class
Non-ducted, up to 1.5 tons	No models in this size class	85.1(50 is the typical model of its size class)DWH09UW3SXETE00/Owith ductless indoor unit DWH09UW3SXETE00/I3 of 10 models have all five ratings · AHRI 202021941
Non-ducted, 2 tons	No models in this size class	None on this board (0 of 2 models have all five ratings)
Non-ducted, 2.5–3 tons	No models in this size class	None on this board (0 of 1 models have all five ratings)

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	ATK	WINDAIR
COP at 5°F	beats 76% · 2.20ACI-AUO18SHP-MDucted, up to 1.5 tons	beats 78% · 2.10DWH09UW3SXETE00/ONon-ducted, up to 1.5 tons
Capacity retention at 5°F	beats 92% · 92%ACI-AUO48SHP-MDucted, 3.5–4.5 tons	beats 65% · 78%DWH09UW3SXETE00/ONon-ducted, up to 1.5 tons
HSPF2	beats 93% · 10.0ACI-AUO36SHP-MDucted, 2.5–3 tons	beats 79% · 10.5DWH09UW3SXETE00/ONon-ducted, up to 1.5 tons
SEER2	beats 69% · 17.3ACI-SDAUO30SHPDucted, 2.5–3 tons	beats 96% · 27.5DWH09UW3SXETE00/ONon-ducted, up to 1.5 tons
EER2	beats 50% · 11.7ACI-AUO24SHP-MDucted, 2 tons	beats 93% · 15.5DWH09UW3SXETE00/ONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 95% · 48,500 Btu/hACI-AUO60SHP-MDucted, 3.5–4.5 tons	beats 66% · 11,900 Btu/hDWH18UR3SBBTE/ONon-ducted, up to 1.5 tons

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