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COMFORTSTAR vs ZERO heat pumps

Measured against models of the same size and duct type, ZERO scores higher on 5 of the 6 ratings. COMFORTSTAR has 133 outdoor models, ZERO has 119 outdoor models. COMFORTSTAR and ZERO 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.
COMFORTSTAR 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, ZERO scores higher on 5 of the 6 ratings.
  • COMFORTSTAR
  • ZERO
  • Other ranked manufacturers
COMFORTS…ZERO

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingCOMFORTSTARZERO
Efficiency index50%median —53%median —
COP at 5°F51% (higher)median 2.0045% (higher)median 1.94
Capacity retention at 5°F48%median 71%52%median 74%
HSPF254%median 8.757%median 9.5
SEER249%median 17.158%median 19.0
EER244%median 11.248%median 11.7
Heating capacity at 5°F52%median 20,600 Btu/h55%median 18,750 Btu/h
Outdoor models133119
AHRI certifications461164

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardCOMFORTSTARZERO
CEE 2025 Tier 1 (Split ASHP)53.4%71 models70.6%84 models
CEE 2026 Tier 1 (Split ASHP)53.4%71 models69.7%83 models
CEE Advanced Tier (Split ASHP)1.5%2 models0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)46.6%62 models64.7%77 models
DOE Cold Climate Heat Pump Challenge1.5%2 models0%0 models
ENERGY STAR Cold Climate30.1%40 models52.9%63 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 · 10 groups where both have models
  • COMFORTSTAR
  • ZERO
  • All models of the group
Ducted, up to 1.5 tons1.901,783 modelsDucted, 2 tons2.001,090 modelsDucted, 2.5–3 tons2.001,909 modelsDucted, 3.5–4.5 tons2.002,224 modelsDucted, 5 tons and up2.00321 modelsNon-ducted, up to 1.5 tons1.953,455 modelsNon-ducted, 2 tons2.00863 modelsNon-ducted, 2.5–3 tons2.001,106 modelsNon-ducted, 3.5–4.5 tons2.00564 modelsNon-ducted, 5 tons and up2.0585 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 typeCOMFORTSTARZERO
Ducted, up to 1.5 tons17 · index 67%7 · index 68%
Ducted, 2 tons17 · index 48%13 · index 51%
Ducted, 2.5–3 tons31 · index 49%20 · index 54%
Ducted, 3.5–4.5 tons36 · index 49%26 · index 54%
Ducted, 5 tons and up2 · index 64%2 · index 64%
Non-ducted, up to 1.5 tons25 · index 56%39 · index 53%
Non-ducted, 2 tons7 · index 46%9 · index 50%
Non-ducted, 2.5–3 tons18 · index 44%13 · index 45%
Non-ducted, 3.5–4.5 tons11 · index 39%6 · index 52%
Non-ducted, 5 tons and up1 · index 27%2 · index 27%

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 typeCOMFORTSTARCold-climate score, best modelZEROCold-climate score, best model
Ducted, up to 1.5 tons93.5(50 is the typical model of its size class) (higher)CHF3-06CD(O)with ducted air handler CPA3-06CD(I)13 of 17 models qualify · AHRI 21713837572.6(50 is the typical model of its size class)Z4SOV-18HDMB-USAlso listed as Z3SOV-18HDMB-US5 of 7 models qualify · AHRI 217138401
Ducted, 2 tons77.4(50 is the typical model of its size class) (higher)CHF3-24CD(O)with ducted air handler AHU3-24M12 of 17 models qualify · AHRI 21713836170.4(50 is the typical model of its size class)ZRRV07HPBYFC-18SAlso listed as ZPRVO7HPBYFC-18S, ZPRV07HPBYFC-18S11 of 13 models qualify · AHRI 217904930
Ducted, 2.5–3 tons83.2(50 is the typical model of its size class) (higher)CHF3-36DU(O)with ducted air handler CPA3H-36DU(I)12 of 31 models qualify · AHRI 21713838782.5(50 is the typical model of its size class)Z4SOV-36HDMB-USHH13 of 20 models qualify · AHRI 217752806
Ducted, 3.5–4.5 tons82.7(50 is the typical model of its size class)CVH3-48-6SH16 of 36 models qualify · AHRI 21672091982.7(50 is the typical model of its size class)Z4SOV-48HDMB-USHH19 of 26 models qualify · AHRI 217752809
Ducted, 5 tons and upNone on this board (0 of 2 models qualify)None on this board (0 of 2 models qualify)
Non-ducted, up to 1.5 tons94.4(50 is the typical model of its size class) (higher)CHF3-06CD(O)with ductless indoor unit T1W3-06CD(I)17 of 25 models qualify · AHRI 21713838385.9(50 is the typical model of its size class)ZMSB-09HV-USHHR2-Owith ductless indoor unit ZMSB-09HV-USHHR2-I31 of 39 models qualify · AHRI 216097679
Non-ducted, 2 tons89.4(50 is the typical model of its size class) (higher)CHF3-24CD(O)with ductless indoor unit TIP3-24CD(I)4 of 7 models qualify · AHRI 21713837477.2(50 is the typical model of its size class)ZMSB-24HV-USHHCR2-Owith ductless indoor unit ZMSB-24HV-USHHCR2-I7 of 9 models qualify · AHRI 216097676
Non-ducted, 2.5–3 tons89.4(50 is the typical model of its size class) (higher)CHF3-36DU(O)with ductless indoor unit FPA3-36DU(I)14 of 18 models qualify · AHRI 21713838472.6(50 is the typical model of its size class)Z4SOV-36HDMB-USHH9 of 13 models qualify · AHRI 217752807
Non-ducted, 3.5–4.5 tons69.9(50 is the typical model of its size class)CVH3-60-6SH9 of 11 models qualify · AHRI 21672092369.9(50 is the typical model of its size class)Z4SOV-53HDMB-USHH6 of 6 models qualify · AHRI 217752813
Non-ducted, 5 tons and upNone on this board (0 of 1 models qualify)None on this board (0 of 2 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 typeCOMFORTSTARAll-around score, best modelZEROAll-around score, best model
Ducted, up to 1.5 tons95.0(50 is the typical model of its size class) (higher)CHF3-06CD(O)with ducted air handler CPA3-06CD(I)15 of 17 models have all five ratings · AHRI 21713837577.4(50 is the typical model of its size class)Z4SOV-18HDMB-USHH6 of 7 models have all five ratings · AHRI 217752800
Ducted, 2 tons78.8(50 is the typical model of its size class)CPP3-24CD(O)with ducted air handler CPA3H-24CD(I)15 of 17 models have all five ratings · AHRI 21672090279.6(50 is the typical model of its size class) (higher)ZOV-24HDGBwith ducted air handler ZAV-24HDGB12 of 13 models have all five ratings · AHRI 217619841
Ducted, 2.5–3 tons83.6(50 is the typical model of its size class)CVH3-36-5SH27 of 31 models have all five ratings · AHRI 21672091683.6(50 is the typical model of its size class)Z4SOV-36HDMB-USHH18 of 20 models have all five ratings · AHRI 217752806
Ducted, 3.5–4.5 tons85.1(50 is the typical model of its size class)CMZ3-55-6Z32 of 36 models have all five ratings · AHRI 21672093485.1(50 is the typical model of its size class)Z4SOV-48HDMB-USAlso listed as Z6SOV-48HDMB-US23 of 26 models have all five ratings · AHRI 217138410
Ducted, 5 tons and up65.3(50 is the typical model of its size class) (higher)CPP3-60DU(O)with ducted air handler CPA3H-60DU(I)2 of 2 models have all five ratings · AHRI 21672090564.7(50 is the typical model of its size class)Z4SOV-60HDMB-US2 of 2 models have all five ratings · AHRI 217138413
Non-ducted, up to 1.5 tons93.8(50 is the typical model of its size class) (higher)CHF3-06CD(O)with ductless indoor unit CPP3-06CD(I)22 of 25 models have all five ratings · AHRI 21713836886.7(50 is the typical model of its size class)ZMSB-09HV-USHHR2-Owith ductless indoor unit ZMSB-09HV-USHHR2-I39 of 39 models have all five ratings · AHRI 216097679
Non-ducted, 2 tons74.3(50 is the typical model of its size class)CPP3-24CD(O)with ductless indoor unit CPP3-24CD(I)6 of 7 models have all five ratings · AHRI 21672088774.3(50 is the typical model of its size class)ZMSB-24HV-USHHR2-Owith ductless indoor unit ZMSB-24HV-USHHR2-I9 of 9 models have all five ratings · AHRI 216097682
Non-ducted, 2.5–3 tons66.3(50 is the typical model of its size class)CVH3-36-5SH17 of 18 models have all five ratings · AHRI 21672091566.3(50 is the typical model of its size class)Z4SOV-36HDMB-USHH13 of 13 models have all five ratings · AHRI 217752805
Non-ducted, 3.5–4.5 tons62.6(50 is the typical model of its size class)CVH3-60-6SH11 of 11 models have all five ratings · AHRI 21672092162.6(50 is the typical model of its size class)Z4SOV-53HDMB-USHH6 of 6 models have all five ratings · AHRI 217752811
Non-ducted, 5 tons and up32.5(50 is the typical model of its size class)CMZ3-62-6Z1 of 1 models have all five ratings · AHRI 21672093632.5(50 is the typical model of its size class)Z4SOV-60HDMB-USAlso listed as Z6SOV-60HDMB-US2 of 2 models have all five ratings · AHRI 217138412

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
RatingCOMFORTSTARZERO
COP at 5°Fbeats 98% · 2.47CPP3-12CD(O)Non-ducted, up to 1.5 tonsbeats 99% · 2.80ZOU-42HDCA-S14Ducted, 3.5–4.5 tons
Capacity retention at 5°Fbeats 99% · 115%CHH32-36Ducted, 2.5–3 tonsbeats 97% · 103%ZRRV07HPBYFC-18SAlso listed as ZPRVO7HPBYFC-18S, ZPRV07HPBYFC-18SDucted, 2 tons
HSPF2beats 99% · 11.0CVH3-48-6SHDucted, 3.5–4.5 tonsbeats 99% · 11.0Z4SOV-48HDMB-USHHDucted, 3.5–4.5 tons
SEER2beats 97% · 22.0C32-MZ-2Ducted, up to 1.5 tonsbeats 99% · 22.0Z3SOV-27HDTB-USDucted, 2.5–3 tons
EER2beats 99% · 14.4CHF3-06CD(O)Ducted, up to 1.5 tonsbeats 93% · 13.3ZOV-24HDGBDucted, 2 tons
Heating capacity at 5°Fbeats 100% · 42,500 Btu/hCHH32-36Ducted, 2.5–3 tonsbeats 97% · 39,000 Btu/hZSOVA-36HDMB-USHHDucted, 2.5–3 tons

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