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.

NOVAIR and ZEPHYR 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, NOVAIR scores higher on 5 of the 6 ratings.

NOVAIR
ZEPHYR
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	NOVAIR	ZEPHYR
Efficiency index	63% (higher)median —	58% (higher)median —
COP at 5°F	48% (higher)median 1.91	40% (higher)median 1.87
Capacity retention at 5°F	64%median 82%	68%median 80%
HSPF2	73% (higher)median 9.8	43% (higher)median 9.0
SEER2	69% (higher)median 21.5	53% (higher)median 21.0
EER2	60% (higher)median 12.5	52% (higher)median 12.5
Heating capacity at 5°F	67% (higher)median 20,000 Btu/h	63% (higher)median 16,200 Btu/h
Outdoor models	25	25
AHRI certifications	53	31

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	NOVAIR	ZEPHYR
CEE 2025 Tier 1 (Split ASHP)	88%22 models	76%19 models
CEE 2026 Tier 1 (Split ASHP)	84%21 models	76%19 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	80%20 models	76%19 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	80%20 models	36%9 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

NOVAIR
ZEPHYR
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	NOVAIR	ZEPHYR
Ducted, up to 1.5 tons	4 · index 57%	None
Ducted, 2 tons	1 · index 51%	1 · index 46%
Ducted, 2.5–3 tons	7 · index 64%	1 · index 63%
Ducted, 3.5–4.5 tons	2 · index 53%	2 · index 51%
Non-ducted, up to 1.5 tons	12 · index 62%	15 · index 58%
Non-ducted, 2 tons	2 · index 81%	4 · index 62%
Non-ducted, 2.5–3 tons	5 · index 68%	1 · index 70%
Non-ducted, 3.5–4.5 tons	None	1 · index 45%

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	NOVAIRCold-climate score, best model	ZEPHYRCold-climate score, best model
Ducted, up to 1.5 tons	63.7(50 is the typical model of its size class)LEA18-EVOX-30-Owith ducted air handler LEA-18/24-ACOIL-410A4 of 4 models qualify · AHRI 214867643	No models in this size class
Ducted, 2 tons	66.5(50 is the typical model of its size class) (higher)LEA24-EVOX-30-Owith ducted air handler LEA24-EVOX-30-I1 of 1 models qualify · AHRI 211253513	57.5(50 is the typical model of its size class)ZE-24HPBwith ducted air handler AH-24B1 of 1 models qualify · AHRI 207036640
Ducted, 2.5–3 tons	78.6(50 is the typical model of its size class) (higher)LEA36-EVOX-30-Owith ducted air handler LEA-30/36-ACOIL-410A6 of 7 models qualify · AHRI 214867644	75.1(50 is the typical model of its size class)ZE-36HPBwith ducted air handler AH-36B1 of 1 models qualify · AHRI 207036642
Ducted, 3.5–4.5 tons	73.8(50 is the typical model of its size class) (higher)LEA48-EVOX-30-Owith ducted air handler LEA48-EVOX-30-I2 of 2 models qualify · AHRI 211253514	56.6(50 is the typical model of its size class)ZE-48HPBwith ducted air handler AH-48B1 of 2 models qualify · AHRI 207036646
Non-ducted, up to 1.5 tons	89.3(50 is the typical model of its size class) (higher)LEA09SZ25SK-Owith ductless indoor unit 2LEA06UUSK-I9 of 12 models qualify · AHRI 211709681	72.9(50 is the typical model of its size class)ZE-09UH24SCOwith ductless indoor unit ZE-09UH24SCI11 of 15 models qualify · AHRI 208287539
Non-ducted, 2 tons	84.5(50 is the typical model of its size class) (higher)LEA24SZ35SK-Owith ductless indoor unit 2LEA24UUSK-I2 of 2 models qualify · AHRI 211709685	64.0(50 is the typical model of its size class)ZE-24CA22SEXTwith ductless indoor unit ZE-24CA22SINT3 of 4 models qualify · AHRI 203446804
Non-ducted, 2.5–3 tons	79.3(50 is the typical model of its size class) (higher)LEA36MZ-4P-35SK-O*4 of 5 models qualify · AHRI 212920682	64.0(50 is the typical model of its size class)ZE-36M422SCO1 of 1 models qualify · AHRI 206347270
Non-ducted, 3.5–4.5 tons	No models in this size class	41.9(50 is the typical model of its size class)ZE-42M522SCO1 of 1 models qualify · AHRI 206346135

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	NOVAIRAll-around score, best model	ZEPHYRAll-around score, best model
Ducted, up to 1.5 tons	63.4(50 is the typical model of its size class)LEA18-EVOX-30-Owith ducted air handler LEA18-EVOX-30-I4 of 4 models have all five ratings · AHRI 211253511	No models in this size class
Ducted, 2 tons	65.8(50 is the typical model of its size class) (higher)LEA24-EVOX-30-Owith ducted air handler LEA24-EVOX-30-I1 of 1 models have all five ratings · AHRI 211253513	46.3(50 is the typical model of its size class)ZE-24HPBwith ducted air handler AH-24B1 of 1 models have all five ratings · AHRI 207036640
Ducted, 2.5–3 tons	74.6(50 is the typical model of its size class) (higher)LEA28MZ-3P-35SK-O7 of 7 models have all five ratings · AHRI 209416882	63.2(50 is the typical model of its size class)ZE-36HPBwith ducted air handler AH-36B1 of 1 models have all five ratings · AHRI 207036642
Ducted, 3.5–4.5 tons	53.3(50 is the typical model of its size class)LEA60-EVOX-30-Owith ducted air handler LEA60-EVOX-30-I2 of 2 models have all five ratings · AHRI 211253512	57.3(50 is the typical model of its size class) (higher)ZE-48HPBwith ducted air handler AH-48B2 of 2 models have all five ratings · AHRI 207036646
Non-ducted, up to 1.5 tons	92.0(50 is the typical model of its size class) (higher)LEA09SZ25SK-Owith ductless indoor unit 2LEA06UUSK-I12 of 12 models have all five ratings · AHRI 211709681	81.4(50 is the typical model of its size class)ZE-09UH24SCOwith ductless indoor unit ZE-09UH24SCI11 of 15 models have all five ratings · AHRI 208287539
Non-ducted, 2 tons	84.3(50 is the typical model of its size class) (higher)LEA24SZ35SK-Owith ductless indoor unit 2LEA24UUSK-I2 of 2 models have all five ratings · AHRI 211709685	67.5(50 is the typical model of its size class)ZE-24M322SCO3 of 4 models have all five ratings · AHRI 206346130
Non-ducted, 2.5–3 tons	82.8(50 is the typical model of its size class) (higher)LEA36MZ-4P-35SK-O*5 of 5 models have all five ratings · AHRI 212920682	69.5(50 is the typical model of its size class)ZE-36M422SCO1 of 1 models have all five ratings · AHRI 206347270
Non-ducted, 3.5–4.5 tons	No models in this size class	44.5(50 is the typical model of its size class)ZE-42M522SCO1 of 1 models have all five ratings · AHRI 206346134

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	NOVAIR	ZEPHYR
COP at 5°F	beats 97% · 2.39LEA12SZ25SK-ONon-ducted, up to 1.5 tons	beats 81% · 2.13ZE-24CA22SEXTNon-ducted, 2 tons
Capacity retention at 5°F	beats 92% · 107%LEA09SZ25SK-ONon-ducted, up to 1.5 tons	beats 99% · 113%ZE-36M422SCONon-ducted, 2.5–3 tons
HSPF2	beats 98% · 13.6LEA09SZ25SK-ONon-ducted, up to 1.5 tons	beats 83% · 9.5ZE-36HPBDucted, 2.5–3 tons
SEER2	beats 98% · 28.1LEA09SZ35SK-ONon-ducted, up to 1.5 tons	beats 89% · 25.5ZE-09UH24SCONon-ducted, up to 1.5 tons
EER2	beats 98% · 16.2LEA09SZ35SK-ONon-ducted, up to 1.5 tons	beats 89% · 14.5ZE-09UH24SCONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 96% · 20,000 Btu/hLEA20MZ-2P-35SK-ONon-ducted, up to 1.5 tons	beats 92% · 18,000 Btu/hZE-18M222SCONon-ducted, up to 1.5 tons

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NOVAIR vs ZEPHYR heat pumps