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.

Gridless and KARDA 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, Gridless and KARDA split the 6 ratings 3–3.

Gridless
KARDA
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	Gridless	KARDA
Efficiency index	60%median —	66%median —
COP at 5°F	40% (higher)median 1.84	38% (higher)median 1.89
Capacity retention at 5°F	77% (higher)median 86%	67% (higher)median 94%
HSPF2	60%median 9.5	78%median 10.5
SEER2	68%median 21.0	78%median 21.1
EER2	56%median 12.5	63%median 12.0
Heating capacity at 5°F	67% (higher)median 22,800 Btu/h	64% (higher)median 17,700 Btu/h
Outdoor models	11	11
AHRI certifications	11	33

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	Gridless	KARDA
CEE 2025 Tier 1 (Split ASHP)	100%11 models	100%11 models
CEE 2026 Tier 1 (Split ASHP)	100%11 models	90.9%10 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	100%11 models	81.8%9 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	90.9%10 models	72.7%8 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 · 7 groups where both have models

Gridless
KARDA
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	Gridless	KARDA
Ducted, 2 tons	1 · index 46%	2 · index 80%
Ducted, 2.5–3 tons	1 · index 63%	2 · index 64%
Ducted, 3.5–4.5 tons	1 · index 57%	1 · index 64%
Ducted, up to 1.5 tons	None	5 · index 61%
Non-ducted, up to 1.5 tons	4 · index 63%	5 · index 71%
Non-ducted, 2 tons	2 · index 64%	1 · index 66%
Non-ducted, 2.5–3 tons	1 · index 70%	2 · index 60%
Non-ducted, 3.5–4.5 tons	1 · index 45%	1 · index 48%

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	GridlessCold-climate score, best model	KARDACold-climate score, best model
Ducted, up to 1.5 tons	No models in this size class	74.9(50 is the typical model of its size class)3KARDA09SZOwith ducted air handler 3KARDA09UVD5 of 5 models qualify · AHRI 207796637
Ducted, 2 tons	57.5(50 is the typical model of its size class)O-AYC24SD-1with ducted air handler I-AYC24VAH-11 of 1 models qualify · AHRI 213249673	79.4(50 is the typical model of its size class) (higher)1KARDA24SZO20.5with ducted air handler 2PAMSDH24Also listed as 3KARDA24SZO2 of 2 models qualify · AHRI 206348123
Ducted, 2.5–3 tons	75.1(50 is the typical model of its size class) (higher)O-AYC36SD-1with ducted air handler I-AYC36VAH-11 of 1 models qualify · AHRI 213249674	57.4(50 is the typical model of its size class)3KARDA27MZ31 of 2 models qualify · AHRI 207657362
Ducted, 3.5–4.5 tons	56.6(50 is the typical model of its size class)O-AYC48SD-1with ducted air handler I-AYC48VAH-11 of 1 models qualify · AHRI 213249675	None on this board (0 of 1 models qualify)
Non-ducted, up to 1.5 tons	72.9(50 is the typical model of its size class)O-AYD09SD-1with ductless indoor unit I-AYD09W-14 of 4 models qualify · AHRI 213265552	77.0(50 is the typical model of its size class) (higher)3KARDA12SZOwith ductless indoor unit 3KARDA12CON-24 of 5 models qualify · AHRI 210410112
Non-ducted, 2 tons	56.8(50 is the typical model of its size class)O-AYD24SD-32 of 2 models qualify · AHRI 213255584	86.1(50 is the typical model of its size class) (higher)3KARDA24SZOwith ductless indoor unit 3KARDA24UVC1 of 1 models qualify · AHRI 207796643
Non-ducted, 2.5–3 tons	64.0(50 is the typical model of its size class) (higher)O-AYD36SD-41 of 1 models qualify · AHRI 213255585	49.3(50 is the typical model of its size class)3KARDA27MZ31 of 2 models qualify · AHRI 207657363
Non-ducted, 3.5–4.5 tons	41.8(50 is the typical model of its size class)O-AYD42SD-51 of 1 models qualify · AHRI 213255586	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	GridlessAll-around score, best model	KARDAAll-around score, best model
Ducted, up to 1.5 tons	No models in this size class	85.2(50 is the typical model of its size class)3KARDA09SZOwith ducted air handler 3KARDA09UVD5 of 5 models have all five ratings · AHRI 207796637
Ducted, 2 tons	46.3(50 is the typical model of its size class)O-AYC24SD-1with ducted air handler I-AYC24VAH-11 of 1 models have all five ratings · AHRI 213249673	80.1(50 is the typical model of its size class) (higher)1KARDA24SZO20.5with ducted air handler 2PAMSDH24Also listed as 3KARDA24SZO2 of 2 models have all five ratings · AHRI 206348123
Ducted, 2.5–3 tons	63.2(50 is the typical model of its size class)O-AYC36SD-1with ducted air handler I-AYC36VAH-11 of 1 models have all five ratings · AHRI 213249674	71.5(50 is the typical model of its size class) (higher)3KARDA27MZ32 of 2 models have all five ratings · AHRI 207657362
Ducted, 3.5–4.5 tons	57.3(50 is the typical model of its size class)O-AYC48SD-1with ducted air handler I-AYC48VAH-11 of 1 models have all five ratings · AHRI 213249675	63.5(50 is the typical model of its size class) (higher)3KARDA48MZ51 of 1 models have all five ratings · AHRI 207657369
Non-ducted, up to 1.5 tons	81.4(50 is the typical model of its size class)O-AYD09SD-1with ductless indoor unit I-AYD09W-14 of 4 models have all five ratings · AHRI 213265552	84.4(50 is the typical model of its size class) (higher)3KARDA09SZOwith ductless indoor unit 3KARDA09UVW5 of 5 models have all five ratings · AHRI 207430429
Non-ducted, 2 tons	67.5(50 is the typical model of its size class)O-AYD24SD-32 of 2 models have all five ratings · AHRI 213255584	70.7(50 is the typical model of its size class) (higher)3KARDA24SZOwith ductless indoor unit 3KARDA24UVW1 of 1 models have all five ratings · AHRI 207430431
Non-ducted, 2.5–3 tons	69.5(50 is the typical model of its size class) (higher)O-AYD36SD-41 of 1 models have all five ratings · AHRI 213255585	66.7(50 is the typical model of its size class)3KARDA27MZ32 of 2 models have all five ratings · AHRI 207657363
Non-ducted, 3.5–4.5 tons	44.5(50 is the typical model of its size class)O-AYD42SD-51 of 1 models have all five ratings · AHRI 213255586	48.3(50 is the typical model of its size class) (higher)3KARDA48MZ51 of 1 models have all five ratings · AHRI 207657368

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	Gridless	KARDA
COP at 5°F	beats 75% · 2.05O-AYC36SD-1Ducted, 2.5–3 tons	beats 65% · 2.003KARDA18MZ2Non-ducted, up to 1.5 tons
Capacity retention at 5°F	beats 99% · 113%O-AYD36SD-4Non-ducted, 2.5–3 tons	beats 93% · 108%3KARDA09SZODucted, up to 1.5 tons
HSPF2	beats 83% · 9.5O-AYC36SD-1Ducted, 2.5–3 tons	beats 98% · 12.03KARDA09SZODucted, up to 1.5 tons
SEER2	beats 89% · 25.5O-AYD09SD-1Non-ducted, up to 1.5 tons	beats 98% · 21.03KARDA27MZ3Ducted, 2.5–3 tons
EER2	beats 89% · 14.5O-AYD09SD-1Non-ducted, up to 1.5 tons	beats 95% · 15.83KARDA09SZONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 92% · 18,000 Btu/hO-AYD18SD-2Non-ducted, up to 1.5 tons	beats 93% · 27,000 Btu/h1KARDA24SZO20.5Also listed as 3KARDA24SZODucted, 2 tons

More comparisons

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Gridless vs KARDA heat pumps