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.

DIAMONDAIR and Nutech 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, Nutech scores higher on 5 of the 6 ratings.

DIAMONDAIR
Nutech
Other ranked manufacturers

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

Average peer percentile, raw median and rank among ranked manufacturers
Rating	DIAMONDAIR	Nutech
Efficiency index	42%median —	51%median —
COP at 5°F	30%median 1.82	37%median 1.90
Capacity retention at 5°F	34%median 62%	42%median 65%
HSPF2	42%median 7.5	63%median 9.3
SEER2	38%median 14.3	68%median 19.5
EER2	53% (higher)median 11.4	42% (higher)median 10.6
Heating capacity at 5°F	37%median 13,800 Btu/h	45%median 21,400 Btu/h
Outdoor models	25	25
AHRI certifications	74	51

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
Standard	DIAMONDAIR	Nutech
CEE 2025 Tier 1 (Split ASHP)	36%9 models	64%16 models
CEE 2026 Tier 1 (Split ASHP)	28%7 models	48%12 models
CEE Advanced Tier (Split ASHP)	0%0 models	0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)	24%6 models	32%8 models
DOE Cold Climate Heat Pump Challenge	0%0 models	0%0 models
ENERGY STAR Cold Climate	0%0 models	0%0 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

DIAMONDAIR
Nutech
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	DIAMONDAIR	Nutech
Ducted, up to 1.5 tons	2 · index 59%	4 · index 52%
Ducted, 2 tons	2 · index 12%	2 · index 69%
Ducted, 2.5–3 tons	6 · index 40%	7 · index 54%
Ducted, 3.5–4.5 tons	6 · index 31%	6 · index 55%
Ducted, 5 tons and up	1 · index 19%	1 · index 42%
Non-ducted, up to 1.5 tons	7 · index 47%	4 · index 42%
Non-ducted, 2 tons	2 · index 40%	1 · index 27%
Non-ducted, 2.5–3 tons	2 · index 60%	5 · index 55%
Non-ducted, 3.5–4.5 tons	1 · index 40%	4 · 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	DIAMONDAIRCold-climate score, best model	NutechCold-climate score, best model
Ducted, up to 1.5 tons	52.0(50 is the typical model of its size class)DF18M2Z21 of 2 models qualify · AHRI 210857278	65.4(50 is the typical model of its size class) (higher)NOX330-12HFN1-MW5Wwith ducted air handler NTIU-12HWFN1-M3 of 4 models qualify · AHRI 212941749
Ducted, 2 tons	None on this board (0 of 2 models qualify)	79.4(50 is the typical model of its size class)NOD30-24HFN1-MU0Wwith ducted air handler NTIU-24HWFN1-M2 of 2 models qualify · AHRI 212941751
Ducted, 2.5–3 tons	57.4(50 is the typical model of its size class)DF30M2Z31 of 6 models qualify · AHRI 210857281	57.4(50 is the typical model of its size class)N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-M2 of 7 models qualify · AHRI 212941759
Ducted, 3.5–4.5 tons	None on this board (0 of 6 models qualify)	None on this board (0 of 6 models qualify)
Ducted, 5 tons and up	None on this board (0 of 1 models qualify)	None on this board (0 of 1 models qualify)
Non-ducted, up to 1.5 tons	74.8(50 is the typical model of its size class) (higher)D2009SHO2with ductless indoor unit DF2009HMSI23 of 7 models qualify · AHRI 210857265	56.7(50 is the typical model of its size class)NU9WKU1with ductless indoor unit NU9WKU11 of 4 models qualify · AHRI 212941744
Non-ducted, 2 tons	86.1(50 is the typical model of its size class)D2024SHO2with ductless indoor unit DF2024CI21 of 2 models qualify · AHRI 210857272	None on this board (0 of 1 models qualify)
Non-ducted, 2.5–3 tons	49.3(50 is the typical model of its size class)DF30M2Z31 of 2 models qualify · AHRI 210857280	49.3(50 is the typical model of its size class)N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-M2 of 5 models qualify · AHRI 212941758
Non-ducted, 3.5–4.5 tons	None on this board (0 of 1 models qualify)	None on this board (0 of 4 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	DIAMONDAIRAll-around score, best model	NutechAll-around score, best model
Ducted, up to 1.5 tons	59.4(50 is the typical model of its size class)DF18M2Z21 of 2 models have all five ratings · AHRI 210857278	64.5(50 is the typical model of its size class) (higher)NOX330-12HFN1-MW5Wwith ducted air handler NTIU-12HWFN1-M4 of 4 models have all five ratings · AHRI 212941749
Ducted, 2 tons	12.4(50 is the typical model of its size class)D1424HPG21 of 2 models have all five ratings · AHRI 212586117	80.1(50 is the typical model of its size class) (higher)NOD30-24HFN1-MU0Wwith ducted air handler NTIU-24HWFN1-M2 of 2 models have all five ratings · AHRI 212941751
Ducted, 2.5–3 tons	71.5(50 is the typical model of its size class)DF30M2Z34 of 6 models have all five ratings · AHRI 210857281	71.5(50 is the typical model of its size class)N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-M7 of 7 models have all five ratings · AHRI 212941759
Ducted, 3.5–4.5 tons	52.1(50 is the typical model of its size class)DF55M2Z53 of 6 models have all five ratings · AHRI 210857287	63.5(50 is the typical model of its size class) (higher)N5OG-48HFN1-MAlso listed as N2OA-48HFN1-M6 of 6 models have all five ratings · AHRI 212941765
Ducted, 5 tons and up	19.3(50 is the typical model of its size class)D1460HPL21 of 1 models have all five ratings · AHRI 212586122	41.7(50 is the typical model of its size class) (higher)NOE30U-60HFN1-MR0with ducted air handler NVC-60HWFN11 of 1 models have all five ratings · AHRI 212941774
Non-ducted, up to 1.5 tons	84.4(50 is the typical model of its size class) (higher)D2009SHO2with ductless indoor unit DF2009HMSI27 of 7 models have all five ratings · AHRI 210857265	54.6(50 is the typical model of its size class)NU9WKU1with ductless indoor unit NU9WKU14 of 4 models have all five ratings · AHRI 212941744
Non-ducted, 2 tons	70.7(50 is the typical model of its size class) (higher)D2024SHO2with ductless indoor unit DF2024HMSI22 of 2 models have all five ratings · AHRI 210857268	27.2(50 is the typical model of its size class)NU24WKU1with ductless indoor unit NU24WKU11 of 1 models have all five ratings · AHRI 212941747
Non-ducted, 2.5–3 tons	66.7(50 is the typical model of its size class)DF30M2Z32 of 2 models have all five ratings · AHRI 210857280	66.7(50 is the typical model of its size class)N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-M5 of 5 models have all five ratings · AHRI 212941758
Non-ducted, 3.5–4.5 tons	40.4(50 is the typical model of its size class)DF55M2Z51 of 1 models have all five ratings · AHRI 210857286	48.3(50 is the typical model of its size class) (higher)N5OG-48HFN1-MAlso listed as N2OA-48HFN1-M4 of 4 models have all five ratings · AHRI 212941764

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	DIAMONDAIR	Nutech
COP at 5°F	beats 78% · 2.10D1612HMSOFNon-ducted, up to 1.5 tons	beats 87% · 2.01NU36WKU1Non-ducted, 2.5–3 tons
Capacity retention at 5°F	beats 92% · 103%D2024SHO2Non-ducted, 2 tons	beats 92% · 108%NOD30-24HFN1-MU0WDucted, 2 tons
HSPF2	beats 97% · 11.5D2024SHO2Non-ducted, 2 tons	beats 95% · 9.7N5OG-48HFN1-MAlso listed as N2OA-48HFN1-MDucted, 3.5–4.5 tons
SEER2	beats 98% · 21.0DF30M2Z3Ducted, 2.5–3 tons	beats 98% · 21.0N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-MDucted, 2.5–3 tons
EER2	beats 95% · 15.8D2009SHO2Non-ducted, up to 1.5 tons	beats 75% · 12.2N3OJ-27HFN1-MAlso listed as N2OA-27HFN1-MNon-ducted, 2.5–3 tons
Heating capacity at 5°F	beats 90% · 17,200 Btu/hD2018SHO2Non-ducted, up to 1.5 tons	beats 93% · 27,000 Btu/hNOD30-24HFN1-MU0WDucted, 2 tons

More comparisons

Pick any two manufacturers

DIAMONDAIR vs Nutech heat pumps