Skip to content
Rebate.Blue

COMFORTSTAR vs ZERO heat pumps

Measured against models of the same size and duct type, COMFORTSTAR and ZERO split the 6 ratings 3–3. COMFORTSTAR has 117 outdoor models, ZERO has 69 outdoor models. COMFORTSTAR and ZERO have no QMID on file and are not ranked.

New to heat pump ratings? The Simple view explains them in plain words →

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, COMFORTSTAR and ZERO split the 6 ratings 3–3.
  • 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 index48%median —49%median —
COP at 5°F46%median 1.8848%median 1.89
Capacity retention at 5°F44% (higher)median 63%43% (higher)median 70%
HSPF249% (higher)median 8.746% (higher)median 8.6
SEER244%median 17.053%median 19.0
EER244%median 11.046%median 11.0
Heating capacity at 5°F46% (higher)median 17,600 Btu/h44% (higher)median 11,700 Btu/h
Outdoor models11769
AHRI certifications30289

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardCOMFORTSTARZERO
CEE 2025 Tier 1 (Split ASHP)36.8%43 models59.4%41 models
CEE 2026 Tier 1 (Split ASHP)35.9%42 models55.1%38 models
CEE Advanced Tier (Split ASHP)0.9%1 models0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)23.9%28 models47.8%33 models
DOE Cold Climate Heat Pump Challenge0.9%1 models0%0 models
ENERGY STAR Cold Climate22.2%26 models24.6%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 · 9 groups where both have models
  • COMFORTSTAR
  • ZERO
  • 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 typeCOMFORTSTARZERO
Ducted, up to 1.5 tons12 · index 62%2 · index 59%
Ducted, 2 tons10 · index 48%5 · index 69%
Ducted, 2.5–3 tons24 · index 44%7 · index 57%
Ducted, 3.5–4.5 tons22 · index 47%9 · index 63%
Ducted, 5 tons and up5 · index 42%1 · index 57%
Non-ducted, up to 1.5 tons33 · index 47%33 · index 48%
Non-ducted, 2 tons8 · index 42%9 · index 49%
Non-ducted, 2.5–3 tons20 · index 46%8 · index 39%
Non-ducted, 3.5–4.5 tons8 · index 54%3 · index 50%

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 tons74.9(50 is the typical model of its size class) (higher)CHF09CD(O)with ducted air handler CPA-09C8 of 12 models qualify · AHRI 20765893752.0(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models qualify · AHRI 214723150
Ducted, 2 tons80.3(50 is the typical model of its size class)CZP24CD(O)with ducted air handler CPA-24B4 of 10 models qualify · AHRI 20765893380.3(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models qualify · AHRI 212928560
Ducted, 2.5–3 tons79.9(50 is the typical model of its size class) (higher)CHF36CD(O)with ducted air handler CPA-36C6 of 24 models qualify · AHRI 20765894157.4(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 7 models qualify · AHRI 213732663
Ducted, 3.5–4.5 tons86.4(50 is the typical model of its size class) (higher)CXH048CD(O)-DUwith ducted air handler CPA-48DUBAlso listed as CHF48CD(O)6 of 22 models qualify · AHRI 20515044174.9(50 is the typical model of its size class)Z5SOV-48HDM-US1 of 9 models qualify · AHRI 213732669
Ducted, 5 tons and up70.2(50 is the typical model of its size class)CCRT60-1-INV1 of 5 models qualify · AHRI 212601832None on this board (0 of 1 models qualify)
Non-ducted, up to 1.5 tons86.0(50 is the typical model of its size class)CZP09CD(O)with ductless indoor unit CHF09CD(I)11 of 33 models qualify · AHRI 20765892286.0(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH24 of 33 models qualify · AHRI 213917748
Non-ducted, 2 tons86.1(50 is the typical model of its size class) (higher)CHF24CD(O)with ductless indoor unit TIP-242 of 8 models qualify · AHRI 20765895274.2(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US4 of 9 models qualify · AHRI 212928564
Non-ducted, 2.5–3 tons79.3(50 is the typical model of its size class) (higher)CVH-36-4SH3 of 20 models qualify · AHRI 20765898249.3(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 8 models qualify · AHRI 213732662
Non-ducted, 3.5–4.5 tons76.2(50 is the typical model of its size class)CVH-48-5SH4 of 8 models qualify · AHRI 20765898480.5(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US2 of 3 models qualify · AHRI 213732668

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 tons85.2(50 is the typical model of its size class) (higher)CHF09CD(O)with ducted air handler CPA-09C10 of 12 models have all five ratings · AHRI 20765893759.4(50 is the typical model of its size class)Z3SOV-18HDM-US1 of 2 models have all five ratings · AHRI 214723150
Ducted, 2 tons83.8(50 is the typical model of its size class)CZP24CD(O)with ducted air handler CPA-24B6 of 10 models have all five ratings · AHRI 20765893383.8(50 is the typical model of its size class)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models have all five ratings · AHRI 212928560
Ducted, 2.5–3 tons75.4(50 is the typical model of its size class) (higher)CMZ-27-3Z16 of 24 models have all five ratings · AHRI 20765896871.5(50 is the typical model of its size class)Z3SOV-27HDM-US3 of 7 models have all five ratings · AHRI 213732663
Ducted, 3.5–4.5 tons82.0(50 is the typical model of its size class)CVH-48-5SH12 of 22 models have all five ratings · AHRI 20765898582.0(50 is the typical model of its size class)Z5SOV-48HDM-US2 of 9 models have all five ratings · AHRI 213732669
Ducted, 5 tons and up75.1(50 is the typical model of its size class) (higher)CCRT60-1-INV5 of 5 models have all five ratings · AHRI 21260183257.1(50 is the typical model of its size class)ZSOV-60HDM-USwith ducted air handler ZDV-60HDM-US1 of 1 models have all five ratings · AHRI 212928563
Non-ducted, up to 1.5 tons88.4(50 is the typical model of its size class) (higher)CZP09CD(O)with ductless indoor unit CHF09CD(I)30 of 33 models have all five ratings · AHRI 20765892286.7(50 is the typical model of its size class)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH33 of 33 models have all five ratings · AHRI 213917748
Non-ducted, 2 tons84.3(50 is the typical model of its size class) (higher)CHF24CD(O)with ductless indoor unit CHF24CD(I)7 of 8 models have all five ratings · AHRI 20765892972.0(50 is the typical model of its size class)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US9 of 9 models have all five ratings · AHRI 212928564
Non-ducted, 2.5–3 tons82.8(50 is the typical model of its size class) (higher)CVH-36-4SH17 of 20 models have all five ratings · AHRI 20765898266.7(50 is the typical model of its size class)Z3SOV-27HDM-US8 of 8 models have all five ratings · AHRI 213732662
Non-ducted, 3.5–4.5 tons77.9(50 is the typical model of its size class) (higher)CVH-48-5SH5 of 8 models have all five ratings · AHRI 20765898473.8(50 is the typical model of its size class)Z5SOV-48HDM-US3 of 3 models have all five ratings · AHRI 213732668

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 97% · 2.39CZP12CD(O)Non-ducted, up to 1.5 tonsbeats 96% · 2.22ZMSB-24HV-USHHNon-ducted, 2 tons
Capacity retention at 5°Fbeats 95% · 103%CHF36CD(O)Non-ducted, 2.5–3 tonsbeats 84% · 87%Z5SOV-48HDM-USDucted, 3.5–4.5 tons
HSPF2beats 99% · 10.3CXH048CD(O)-DUAlso listed as CHF48CD(O)Ducted, 3.5–4.5 tonsbeats 98% · 11.2ZSOV-24HDM-USDucted, 2 tons
SEER2beats 99% · 24.6CMZ-27-3ZNon-ducted, 2.5–3 tonsbeats 99% · 20.9Z5SOV-48HDM-USDucted, 3.5–4.5 tons
EER2beats 98% · 16.2CHF09CD(O)Non-ducted, up to 1.5 tonsbeats 95% · 15.8ZMSB-09HV-USHHCAlso listed as ZMSB-09HV-USHHC-ONon-ducted, up to 1.5 tons
Heating capacity at 5°Fbeats 98% · 41,000 Btu/hCHF36CD(O)Non-ducted, 2.5–3 tonsbeats 90% · 17,200 Btu/hZMSB-18HV-USHHCAlso listed as ZMSB-18HV-USHHC-ONon-ducted, up to 1.5 tons

More comparisons

Pick any two manufacturers