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DIAMONDAIR vs ZEPHYR heat pumps

Measured against models of the same size and duct type, ZEPHYR scores higher on 5 of the 6 ratings. DIAMONDAIR has 25 outdoor models, ZEPHYR has 25 outdoor models. DIAMONDAIR and ZEPHYR have no QMID on file and are not ranked.

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CompareData as of updated · sources

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 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, ZEPHYR scores higher on 5 of the 6 ratings.
  • DIAMONDAIR
  • ZEPHYR
  • Other ranked manufacturers
DIAMONDA…ZEPHYR

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingDIAMONDAIRZEPHYR
Efficiency index42%median —58%median —
COP at 5°F30%median 1.8240%median 1.87
Capacity retention at 5°F34%median 62%68%median 80%
HSPF242%median 7.543%median 9.0
SEER238%median 14.353%median 21.0
EER253% (higher)median 11.452% (higher)median 12.5
Heating capacity at 5°F37%median 13,800 Btu/h63%median 16,200 Btu/h
Outdoor models2525
AHRI certifications7431

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardDIAMONDAIRZEPHYR
CEE 2025 Tier 1 (Split ASHP)36%9 models76%19 models
CEE 2026 Tier 1 (Split ASHP)28%7 models76%19 models
CEE Advanced Tier (Split ASHP)0%0 models0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)24%6 models76%19 models
DOE Cold Climate Heat Pump Challenge0%0 models0%0 models
ENERGY STAR Cold Climate0%0 models36%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 · 7 groups where both have models
  • DIAMONDAIR
  • ZEPHYR
  • All models of the group
Ducted, up to 1.5 tons2.00884 modelsDucted, 2 tons2.00821 modelsDucted, 2.5–3 tons1.901,614 modelsDucted, 3.5–4.5 tons1.911,492 modelsDucted, 5 tons and up1.90239 modelsNon-ducted, up to 1.5 tons1.902,417 modelsNon-ducted, 2 tons1.87611 modelsNon-ducted, 2.5–3 tons1.85975 modelsNon-ducted, 3.5–4.5 tons1.97438 modelsmedian

Raw ratings are only placed side by side within one size and duct type, where they are comparable.

Source: AHRI Directory · as of

Models per peer group · efficiency index within the group
Size and duct typeDIAMONDAIRZEPHYR
Ducted, up to 1.5 tons2 · index 59%None
Ducted, 2 tons2 · index 12%1 · index 46%
Ducted, 2.5–3 tons6 · index 40%1 · index 63%
Ducted, 3.5–4.5 tons6 · index 31%2 · index 51%
Ducted, 5 tons and up1 · index 19%None
Non-ducted, up to 1.5 tons7 · index 47%15 · index 58%
Non-ducted, 2 tons2 · index 40%4 · index 62%
Non-ducted, 2.5–3 tons2 · index 60%1 · index 70%
Non-ducted, 3.5–4.5 tons1 · index 40%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 typeDIAMONDAIRCold-climate score, best modelZEPHYRCold-climate score, best model
Ducted, up to 1.5 tons52.0(50 is the typical model of its size class)DF18M2Z21 of 2 models qualify · AHRI 210857278No models in this size class
Ducted, 2 tonsNone on this board (0 of 2 models qualify)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 tons57.4(50 is the typical model of its size class)DF30M2Z31 of 6 models qualify · AHRI 21085728175.1(50 is the typical model of its size class) (higher)ZE-36HPBwith ducted air handler AH-36B1 of 1 models qualify · AHRI 207036642
Ducted, 3.5–4.5 tonsNone on this board (0 of 6 models qualify)56.6(50 is the typical model of its size class)ZE-48HPBwith ducted air handler AH-48B1 of 2 models qualify · AHRI 207036646
Ducted, 5 tons and upNone on this board (0 of 1 models qualify)No models in this size class
Non-ducted, up to 1.5 tons74.8(50 is the typical model of its size class) (higher)D2009SHO2with ductless indoor unit DF2009HMSI23 of 7 models qualify · AHRI 21085726572.9(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 tons86.1(50 is the typical model of its size class) (higher)D2024SHO2with ductless indoor unit DF2024CI21 of 2 models qualify · AHRI 21085727264.0(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 tons49.3(50 is the typical model of its size class)DF30M2Z31 of 2 models qualify · AHRI 21085728064.0(50 is the typical model of its size class) (higher)ZE-36M422SCO1 of 1 models qualify · AHRI 206347270
Non-ducted, 3.5–4.5 tonsNone on this board (0 of 1 models qualify)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 typeDIAMONDAIRAll-around score, best modelZEPHYRAll-around score, best model
Ducted, up to 1.5 tons59.4(50 is the typical model of its size class)DF18M2Z21 of 2 models have all five ratings · AHRI 210857278No models in this size class
Ducted, 2 tons12.4(50 is the typical model of its size class)D1424HPG21 of 2 models have all five ratings · AHRI 21258611746.3(50 is the typical model of its size class) (higher)ZE-24HPBwith ducted air handler AH-24B1 of 1 models have all five ratings · AHRI 207036640
Ducted, 2.5–3 tons71.5(50 is the typical model of its size class) (higher)DF30M2Z34 of 6 models have all five ratings · AHRI 21085728163.2(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 tons52.1(50 is the typical model of its size class)DF55M2Z53 of 6 models have all five ratings · AHRI 21085728757.3(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
Ducted, 5 tons and up19.3(50 is the typical model of its size class)D1460HPL21 of 1 models have all five ratings · AHRI 212586122No models in this size class
Non-ducted, up to 1.5 tons84.4(50 is the typical model of its size class) (higher)D2009SHO2with ductless indoor unit DF2009HMSI27 of 7 models have all five ratings · AHRI 21085726581.4(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 tons70.7(50 is the typical model of its size class) (higher)D2024SHO2with ductless indoor unit DF2024HMSI22 of 2 models have all five ratings · AHRI 21085726867.5(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 tons66.7(50 is the typical model of its size class)DF30M2Z32 of 2 models have all five ratings · AHRI 21085728069.5(50 is the typical model of its size class) (higher)ZE-36M422SCO1 of 1 models have all five ratings · AHRI 206347270
Non-ducted, 3.5–4.5 tons40.4(50 is the typical model of its size class)DF55M2Z51 of 1 models have all five ratings · AHRI 21085728644.5(50 is the typical model of its size class) (higher)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
RatingDIAMONDAIRZEPHYR
COP at 5°Fbeats 78% · 2.10D1612HMSOFNon-ducted, up to 1.5 tonsbeats 81% · 2.13ZE-24CA22SEXTNon-ducted, 2 tons
Capacity retention at 5°Fbeats 92% · 103%D2024SHO2Non-ducted, 2 tonsbeats 99% · 113%ZE-36M422SCONon-ducted, 2.5–3 tons
HSPF2beats 97% · 11.5D2024SHO2Non-ducted, 2 tonsbeats 83% · 9.5ZE-36HPBDucted, 2.5–3 tons
SEER2beats 98% · 21.0DF30M2Z3Ducted, 2.5–3 tonsbeats 89% · 25.5ZE-09UH24SCONon-ducted, up to 1.5 tons
EER2beats 95% · 15.8D2009SHO2Non-ducted, up to 1.5 tonsbeats 89% · 14.5ZE-09UH24SCONon-ducted, up to 1.5 tons
Heating capacity at 5°Fbeats 90% · 17,200 Btu/hD2018SHO2Non-ducted, up to 1.5 tonsbeats 92% · 18,000 Btu/hZE-18M222SCONon-ducted, up to 1.5 tons

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