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.

DIRECT AIR and ZERO 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, DIRECT AIR scores higher on 6 of the 6 ratings.

DIRECT AIR
ZERO
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	DIRECT AIR	ZERO
Efficiency index	61% (higher)median —	49% (higher)median —
COP at 5°F	53% (higher)median 1.96	48% (higher)median 1.89
Capacity retention at 5°F	61% (higher)median 80%	43% (higher)median 70%
HSPF2	60% (higher)median 9.2	46% (higher)median 8.6
SEER2	56% (higher)median 19.0	53% (higher)median 19.0
EER2	53% (higher)median 11.7	46% (higher)median 11.0
Heating capacity at 5°F	56% (higher)median 19,000 Btu/h	44% (higher)median 11,700 Btu/h
Outdoor models	68	69
AHRI certifications	148	89

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	DIRECT AIR	ZERO
CEE 2025 Tier 1 (Split ASHP)	60.3%41 models	59.4%41 models
CEE 2026 Tier 1 (Split ASHP)	58.8%40 models	55.1%38 models
CEE Advanced Tier (Split ASHP)	1.5%1 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	54.4%37 models	47.8%33 models
DOE Cold Climate Heat Pump Challenge	1.5%1 models	0%0 models
ENERGY STAR Cold Climate	50%34 models	24.6%17 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 · 9 groups where both have models

DIRECT AIR
ZERO
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	DIRECT AIR	ZERO
Ducted, up to 1.5 tons	12 · index 61%	2 · index 59%
Ducted, 2 tons	5 · index 67%	5 · index 69%
Ducted, 2.5–3 tons	13 · index 55%	7 · index 57%
Ducted, 3.5–4.5 tons	11 · index 58%	9 · index 63%
Ducted, 5 tons and up	2 · index 49%	1 · index 57%
Non-ducted, up to 1.5 tons	27 · index 65%	33 · index 48%
Non-ducted, 2 tons	6 · index 66%	9 · index 49%
Non-ducted, 2.5–3 tons	9 · index 59%	8 · index 39%
Non-ducted, 3.5–4.5 tons	4 · index 58%	3 · index 50%

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	DIRECT AIRCold-climate score, best model	ZEROCold-climate score, best model
Ducted, up to 1.5 tons	74.9(50 is the typical model of its size class) (higher)DIRM-09HXPRO28-1Zwith ducted air handler DIRM-09HP-DUH9 of 12 models qualify · AHRI 207743749	52.0(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models qualify · AHRI 214723150
Ducted, 2 tons	80.3(50 is the typical model of its size class)DIRM-24DA25-1Zwith ducted air handler DIRM-24HP-DU4 of 5 models qualify · AHRI 207743759	80.3(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models qualify · AHRI 212928560
Ducted, 2.5–3 tons	78.6(50 is the typical model of its size class) (higher)DIRM-36MAGICPRO20-OUwith ducted air handler DIRM-36MAGICPRO20-COIL5 of 13 models qualify · AHRI 212388351	57.4(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 7 models qualify · AHRI 213732663
Ducted, 3.5–4.5 tons	74.9(50 is the typical model of its size class)DIRM-48HXPRO28-5Z3 of 11 models qualify · AHRI 207743795	74.9(50 is the typical model of its size class)Z5SOV-48HDM-US1 of 9 models qualify · AHRI 213732669
Ducted, 5 tons and up	None on this board (0 of 2 models qualify)	None on this board (0 of 1 models qualify)
Non-ducted, up to 1.5 tons	89.3(50 is the typical model of its size class) (higher)DIRM-06HXPRO28-1Zwith ductless indoor unit DIRM-06HP-WM20 of 27 models qualify · AHRI 207743723	86.0(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH24 of 33 models qualify · AHRI 213917748
Non-ducted, 2 tons	86.1(50 is the typical model of its size class) (higher)DIRM-24HXPRO28-1Zwith ductless indoor unit DIRM-24HP-CA5 of 6 models qualify · AHRI 207743744	74.2(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US4 of 9 models qualify · AHRI 212928564
Non-ducted, 2.5–3 tons	79.3(50 is the typical model of its size class) (higher)DIRM-36HXPRO28-4Z2 of 9 models qualify · AHRI 207743791	49.3(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 8 models qualify · AHRI 213732662
Non-ducted, 3.5–4.5 tons	76.2(50 is the typical model of its size class)DIRM-48HXPRO28-5Z2 of 4 models qualify · AHRI 207743794	80.5(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US2 of 3 models qualify · AHRI 213732668

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	DIRECT AIRAll-around score, best model	ZEROAll-around score, best model
Ducted, up to 1.5 tons	85.2(50 is the typical model of its size class) (higher)DIRM-09HXPRO28-1Zwith ducted air handler DIRM-09HP-DUH11 of 12 models have all five ratings · AHRI 207743749	59.4(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models have all five ratings · AHRI 214723150
Ducted, 2 tons	83.8(50 is the typical model of its size class)DIRM-24DA25-1Zwith ducted air handler DIRM-24HP-DU4 of 5 models have all five ratings · AHRI 207743759	83.8(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models have all five ratings · AHRI 212928560
Ducted, 2.5–3 tons	75.4(50 is the typical model of its size class) (higher)DIRM-27DA25-3Z10 of 13 models have all five ratings · AHRI 207743777	71.5(50 is the typical model of its size class)Z3SOV-27HDM-US3 of 7 models have all five ratings · AHRI 213732663
Ducted, 3.5–4.5 tons	82.0(50 is the typical model of its size class)DIRM-48HXPRO28-5Z6 of 11 models have all five ratings · AHRI 207743795	82.0(50 is the typical model of its size class)Z5SOV-48HDM-US2 of 9 models have all five ratings · AHRI 213732669
Ducted, 5 tons and up	54.5(50 is the typical model of its size class)MOE30U-60HFN1-Mwith ducted air handler MHG-60HWFN1-MW2 of 2 models have all five ratings · AHRI 203269797	57.1(50 is the typical model of its size class) (higher)ZSOV-60HDM-USwith ducted air handler ZDV-60HDM-US1 of 1 models have all five ratings · AHRI 212928563
Non-ducted, up to 1.5 tons	92.0(50 is the typical model of its size class) (higher)DIRM-06HXPRO28-1Zwith ductless indoor unit DIRM-06HP-WM22 of 27 models have all five ratings · AHRI 207743723	86.7(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH33 of 33 models have all five ratings · AHRI 213917748
Non-ducted, 2 tons	84.3(50 is the typical model of its size class) (higher)DIRM-24HXPRO28-1Zwith ductless indoor unit DIRM-24HP-WM5 of 6 models have all five ratings · AHRI 207743727	72.0(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US9 of 9 models have all five ratings · AHRI 212928564
Non-ducted, 2.5–3 tons	82.8(50 is the typical model of its size class) (higher)DIRM-36HXPRO28-4Z7 of 9 models have all five ratings · AHRI 207743791	66.7(50 is the typical model of its size class)Z3SOV-27HDM-US8 of 8 models have all five ratings · AHRI 213732662
Non-ducted, 3.5–4.5 tons	77.9(50 is the typical model of its size class) (higher)DIRM-48HXPRO28-5Z3 of 4 models have all five ratings · AHRI 207743794	73.8(50 is the typical model of its size class)Z5SOV-48HDM-US3 of 3 models have all five ratings · AHRI 213732668

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	DIRECT AIR	ZERO
COP at 5°F	beats 97% · 2.39DIRM-12DA25-1ZNon-ducted, up to 1.5 tons	beats 96% · 2.22ZMSB-24HV-USHHNon-ducted, 2 tons
Capacity retention at 5°F	beats 93% · 108%DIRM-09HXPRO28-1ZDucted, up to 1.5 tons	beats 84% · 87%Z5SOV-48HDM-USDucted, 3.5–4.5 tons
HSPF2	beats 98% · 13.6DIRM-06HXPRO28-1ZNon-ducted, up to 1.5 tons	beats 98% · 11.2ZSOV-24HDM-USDucted, 2 tons
SEER2	beats 99% · 24.6DIRM-27DA25-3ZNon-ducted, 2.5–3 tons	beats 99% · 20.9Z5SOV-48HDM-USDucted, 3.5–4.5 tons
EER2	beats 98% · 16.2DIRM-09HXPRO28-1ZNon-ducted, up to 1.5 tons	beats 95% · 15.8ZMSB-09HV-USHHCAlso listed as ZMSB-09HV-USHHC-ONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 96% · 20,000 Btu/hDIRM-18HXPRO28-2ZNon-ducted, up to 1.5 tons	beats 90% · 17,200 Btu/hZMSB-18HV-USHHCAlso listed as ZMSB-18HV-USHHC-ONon-ducted, up to 1.5 tons

More comparisons

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DIRECT AIR vs ZERO heat pumps