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.

DIYCOOL 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, DIYCOOL scores higher on 4 of the 6 ratings.

DIYCOOL
ZERO
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	DIYCOOL	ZERO
Efficiency index	54% (higher)median —	49% (higher)median —
COP at 5°F	42%median 1.90	48%median 1.89
Capacity retention at 5°F	62% (higher)median 78%	43% (higher)median 70%
HSPF2	62% (higher)median 9.4	46% (higher)median 8.6
SEER2	59% (higher)median 18.9	53% (higher)median 19.0
EER2	43%median 11.0	46%median 11.0
Heating capacity at 5°F	62% (higher)median 22,530 Btu/h	44% (higher)median 11,700 Btu/h
Outdoor models	75	69
AHRI certifications	170	89

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	DIYCOOL	ZERO
CEE 2025 Tier 1 (Split ASHP)	65.3%49 models	59.4%41 models
CEE 2026 Tier 1 (Split ASHP)	60%45 models	55.1%38 models
CEE Advanced Tier (Split ASHP)	1.3%1 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	54.7%41 models	47.8%33 models
DOE Cold Climate Heat Pump Challenge	1.3%1 models	0%0 models
ENERGY STAR Cold Climate	45.3%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 · 8 groups where both have models

DIYCOOL
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	DIYCOOL	ZERO
Ducted, up to 1.5 tons	9 · index 57%	2 · index 59%
Ducted, 2 tons	8 · index 58%	5 · index 69%
Ducted, 2.5–3 tons	14 · index 52%	7 · index 57%
Ducted, 3.5–4.5 tons	16 · index 56%	9 · index 63%
Ducted, 5 tons and up	None	1 · index 57%
Non-ducted, up to 1.5 tons	21 · index 55%	33 · index 48%
Non-ducted, 2 tons	6 · index 51%	9 · index 49%
Non-ducted, 2.5–3 tons	15 · index 51%	8 · index 39%
Non-ducted, 3.5–4.5 tons	8 · index 47%	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	DIYCOOLCold-climate score, best model	ZEROCold-climate score, best model
Ducted, up to 1.5 tons	86.9(50 is the typical model of its size class) (higher)ACIQ-18-HPBwith ducted air handler ACIQ-18W-WM8 of 9 models qualify · AHRI 213433267	52.0(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models qualify · AHRI 214723150
Ducted, 2 tons	79.4(50 is the typical model of its size class)ACIQ-24ZPL-HP230Bwith ducted air handler ACIQ-24CD-HH-MB7 of 7 models qualify · AHRI 207825560	80.3(50 is the typical model of its size class) (higher)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models qualify · AHRI 212928560
Ducted, 2.5–3 tons	79.9(50 is the typical model of its size class) (higher)ACIQ-36ZPL-HP230Bwith ducted air handler ACIQ-36CD-HH-MB10 of 15 models qualify · AHRI 210857341	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	86.4(50 is the typical model of its size class) (higher)ACIQ-48ZPL-HP230Bwith ducted air handler ACIQ-48CD-HH-MB12 of 16 models qualify · AHRI 210857342	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	No models in this size class	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)ACIQ-06ZPL-HP230Bwith ductless indoor unit ACIQ-06W-HH-MC11 of 21 models qualify · AHRI 210857334	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	85.4(50 is the typical model of its size class) (higher)ACIQ-24ZPL-HP230Bwith ductless indoor unit ACIQ-24FM-HH-MB3 of 6 models qualify · AHRI 207825563	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)ACIQ-36Z-HH-M4B7 of 15 models qualify · AHRI 207825594	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	76.8(50 is the typical model of its size class)ACIQ-60ZPL-HP230Bwith ductless indoor unit ACIQ-60FM-HH-MB5 of 8 models qualify · AHRI 210857346	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	DIYCOOLAll-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)ACIQ-09ZPL-HP230Bwith ducted air handler ACIQ-09CD-HH-MB9 of 9 models have all five ratings · AHRI 207825557	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	80.1(50 is the typical model of its size class)ACIQ-24ZPL-HP230Bwith ducted air handler ACIQ-24CD-HH-MB8 of 8 models have all five ratings · AHRI 207825560	83.8(50 is the typical model of its size class) (higher)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)ES-27Z-M3B14 of 14 models have all five ratings · AHRI 210857405	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)ACIQ-48Z-HH-M5B15 of 15 models have all five ratings · AHRI 207825598	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	41.7(50 is the typical model of its size class)ACIQ-60-EHPBwith ducted air handler ACIQ-60AHB1 of 1 models have all five ratings · AHRI 213433261	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)ACIQ-06ZPL-HP230Bwith ductless indoor unit ACIQ-06W-HH-MC21 of 21 models have all five ratings · AHRI 210857334	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)ACIQ-24ZPL-HP230Bwith ductless indoor unit ACIQ-24W-HH-MB6 of 6 models have all five ratings · AHRI 207825553	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)ACIQ-36Z-HH-M4B13 of 15 models have all five ratings · AHRI 207825594	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)ACIQ-48Z-HH-M5B8 of 8 models have all five ratings · AHRI 207825597	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	DIYCOOL	ZERO
COP at 5°F	beats 91% · 2.21ACIQ-24ZPL-HP230BNon-ducted, 2 tons	beats 96% · 2.22ZMSB-24HV-USHHNon-ducted, 2 tons
Capacity retention at 5°F	beats 99% · 144%SC-09ZPL-HP230Non-ducted, up to 1.5 tons	beats 84% · 87%Z5SOV-48HDM-USDucted, 3.5–4.5 tons
HSPF2	beats 99% · 10.3ACIQ-48ZPL-HP230BDucted, 3.5–4.5 tons	beats 98% · 11.2ZSOV-24HDM-USDucted, 2 tons
SEER2	beats 99% · 24.6ES-27Z-M3BNon-ducted, 2.5–3 tons	beats 99% · 20.9Z5SOV-48HDM-USDucted, 3.5–4.5 tons
EER2	beats 99% · 16.6SC-09ZPL-HP230Non-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 99% · 56,500 Btu/hACIQ-60ZPL-HP230BNon-ducted, 3.5–4.5 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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DIYCOOL vs ZERO heat pumps