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 6 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	76% (higher)median —	63% (higher)median —
COP at 5°F	59% (higher)median 2.00	57% (higher)median 2.00
Capacity retention at 5°F	75% (higher)median 96%	64% (higher)median 80%
HSPF2	80% (higher)median 10.5	59% (higher)median 10.0
SEER2	83% (higher)median 24.0	67% (higher)median 22.0
EER2	81% (higher)median 13.0	65% (higher)median 12.3
Heating capacity at 5°F	71% (higher)median 20,200 Btu/h	57% (higher)median 13,400 Btu/h
Outdoor models	42	23
AHRI certifications	119	49

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)	97.6%41 models	100%23 models
CEE 2026 Tier 1 (Split ASHP)	97.6%41 models	95.7%22 models
CEE Advanced Tier (Split ASHP)	4.8%2 models	8.7%2 models
Xcel Energy Colorado cold-climate ASHP (2025)	100%42 models	82.6%19 models
DOE Cold Climate Heat Pump Challenge	4.8%2 models	8.7%2 models
ENERGY STAR Cold Climate	100%42 models	73.9%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

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	10 · index 77%	1 · index 65%
Ducted, 2 tons	2 · index 68%	1 · index 80%
Ducted, 2.5–3 tons	4 · index 75%	3 · index 71%
Ducted, 3.5–4.5 tons	4 · index 80%	2 · index 71%
Ducted, 5 tons and up	None	1 · index 81%
Non-ducted, up to 1.5 tons	19 · index 78%	14 · index 62%
Non-ducted, 2 tons	3 · index 73%	2 · index 48%
Non-ducted, 2.5–3 tons	9 · index 78%	2 · index 63%
Non-ducted, 3.5–4.5 tons	5 · index 68%	1 · index 44%

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	93.5(50 is the typical model of its size class) (higher)LEA06SZ36-Owith ducted air handler LEA06DUCT-I10 of 10 models qualify · AHRI 217606302	66.2(50 is the typical model of its size class)ZE-518M2251 of 1 models qualify · AHRI 216684162
Ducted, 2 tons	75.8(50 is the typical model of its size class)LEA24CEN36-Owith ducted air handler LEA24HH-CEN-I2 of 2 models qualify · AHRI 218788024	82.1(50 is the typical model of its size class) (higher)ZE-624HPAwith ducted air handler AH-624A1 of 1 models qualify · AHRI 215381145
Ducted, 2.5–3 tons	82.5(50 is the typical model of its size class)LEA36MZ5P36-O4 of 4 models qualify · AHRI 217606266	87.9(50 is the typical model of its size class) (higher)ZE-636HPAwith ducted air handler AH-636A3 of 3 models qualify · AHRI 215381146
Ducted, 3.5–4.5 tons	82.7(50 is the typical model of its size class) (higher)LEA48MZ6P36-O4 of 4 models qualify · AHRI 217606269	77.3(50 is the typical model of its size class)ZE-648HPAwith ducted air handler AH-648A2 of 2 models qualify · AHRI 215381147
Ducted, 5 tons and up	No models in this size class	88.7(50 is the typical model of its size class)ZE-660HPAwith ducted air handler AH-660A1 of 1 models qualify · AHRI 215381148
Non-ducted, up to 1.5 tons	96.7(50 is the typical model of its size class) (higher)LEA06SZ36-Owith ductless indoor unit 4LEA06USK-I18 of 19 models qualify · AHRI 217606280	89.7(50 is the typical model of its size class)ZE-09UB32Owith ductless indoor unit ZE-09UB32I10 of 14 models qualify · AHRI 217596868
Non-ducted, 2 tons	89.4(50 is the typical model of its size class) (higher)LEA24SZ36-Owith ductless indoor unit LEA24CASS-I3 of 3 models qualify · AHRI 217606301	54.1(50 is the typical model of its size class)ZE-24CB25Owith ductless indoor unit ZE-24CB25AI2 of 2 models qualify · AHRI 218046582
Non-ducted, 2.5–3 tons	78.0(50 is the typical model of its size class) (higher)LEA36MZ5P36-O9 of 9 models qualify · AHRI 217606267	53.7(50 is the typical model of its size class)ZE-536M4252 of 2 models qualify · AHRI 216684171
Non-ducted, 3.5–4.5 tons	73.4(50 is the typical model of its size class) (higher)LEA48MZ6P36-O5 of 5 models qualify · AHRI 217606270	16.4(50 is the typical model of its size class)ZE-542M5251 of 1 models qualify · AHRI 216684168

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	95.0(50 is the typical model of its size class) (higher)LEA06SZ36-Owith ducted air handler LEA06DUCT-I10 of 10 models have all five ratings · AHRI 217606302	64.6(50 is the typical model of its size class)ZE-518M2251 of 1 models have all five ratings · AHRI 216684162
Ducted, 2 tons	71.7(50 is the typical model of its size class)LEA24CEN36-Owith ducted air handler LEA24HH-CEN-I2 of 2 models have all five ratings · AHRI 218788024	79.5(50 is the typical model of its size class) (higher)ZE-624HPAwith ducted air handler AH-624A1 of 1 models have all five ratings · AHRI 215381145
Ducted, 2.5–3 tons	83.6(50 is the typical model of its size class) (higher)LEA36MZ5P36-O4 of 4 models have all five ratings · AHRI 217606266	82.3(50 is the typical model of its size class)ZE-636HPAwith ducted air handler AH-636A3 of 3 models have all five ratings · AHRI 215381146
Ducted, 3.5–4.5 tons	83.9(50 is the typical model of its size class) (higher)LEA48MZ6P36-O4 of 4 models have all five ratings · AHRI 217606269	82.3(50 is the typical model of its size class)ZE-648HPAwith ducted air handler AH-648A2 of 2 models have all five ratings · AHRI 215381147
Ducted, 5 tons and up	No models in this size class	81.1(50 is the typical model of its size class)ZE-660HPAwith ducted air handler AH-660A1 of 1 models have all five ratings · AHRI 215381148
Non-ducted, up to 1.5 tons	96.2(50 is the typical model of its size class) (higher)LEA06SZ36-Owith ductless indoor unit 4LEA06USK-I18 of 19 models have all five ratings · AHRI 217606280	94.5(50 is the typical model of its size class)ZE-09UB32Owith ductless indoor unit ZE-09UB32I14 of 14 models have all five ratings · AHRI 217596868
Non-ducted, 2 tons	86.8(50 is the typical model of its size class) (higher)LEA24SZ26-Owith ductless indoor unit 4LEA24USK-I3 of 3 models have all five ratings · AHRI 217606297	61.3(50 is the typical model of its size class)ZE-24CB25Owith ductless indoor unit ZE-24CB25AI2 of 2 models have all five ratings · AHRI 218046582
Non-ducted, 2.5–3 tons	83.1(50 is the typical model of its size class) (higher)LEA28MZ-4P-454-O*Also listed as LEA27-MZ-LCT- 454-O9 of 9 models have all five ratings · AHRI 218372843	64.2(50 is the typical model of its size class)ZE-527M3252 of 2 models have all five ratings · AHRI 216684164
Non-ducted, 3.5–4.5 tons	75.6(50 is the typical model of its size class) (higher)LEA48MZ6P36-O5 of 5 models have all five ratings · AHRI 217606268	43.7(50 is the typical model of its size class)ZE-542M5251 of 1 models have all five ratings · AHRI 216684168

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 99% · 2.51LEA12SZ26-ONon-ducted, up to 1.5 tons	beats 100% · 2.53ZE-18CB22ONon-ducted, up to 1.5 tons
Capacity retention at 5°F	beats 100% · 150%LEA06HH-SK-ONon-ducted, up to 1.5 tons	beats 94% · 75%ZE-660HPADucted, 5 tons and up
HSPF2	beats 100% · 15.6LEA06HH-SK-ONon-ducted, up to 1.5 tons	beats 96% · 10.5ZE-636HPADucted, 2.5–3 tons
SEER2	beats 100% · 35.0LEA06HH-SK-ONon-ducted, up to 1.5 tons	beats 99% · 32.0ZE-09UB32ONon-ducted, up to 1.5 tons
EER2	beats 99% · 18.0LEA06SZ36-ONon-ducted, up to 1.5 tons	beats 100% · 18.4ZE-09UB32ONon-ducted, up to 1.5 tons
Heating capacity at 5°F	beats 99% · 22,600 Btu/hLEA18HH-SK-ONon-ducted, up to 1.5 tons	beats 93% · 18,000 Btu/hZE-18CB25ONon-ducted, up to 1.5 tons

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NOVAIR vs ZEPHYR heat pumps