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AIR-CON vs ZERO heat pumps

Measured against models of the same size and duct type, AIR-CON scores higher on 4 of the 6 ratings. AIR-CON has 65 outdoor models, ZERO has 69 outdoor models. AIR-CON and ZERO have no QMID on file and are not ranked. They share hardware: 4 equipment families appear under both names.

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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.
AIR-CON 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, AIR-CON scores higher on 4 of the 6 ratings.
  • AIR-CON
  • ZERO
  • Other ranked manufacturers
AIR-CONZERO

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingAIR-CONZERO
Efficiency index55% (higher)median —49% (higher)median —
COP at 5°F47%median 1.8748%median 1.89
Capacity retention at 5°F52% (higher)median 74%43% (higher)median 70%
HSPF246%median 8.846%median 8.6
SEER254% (higher)median 19.053% (higher)median 19.0
EER250% (higher)median 11.546% (higher)median 11.0
Heating capacity at 5°F50% (higher)median 15,500 Btu/h44% (higher)median 11,700 Btu/h
Outdoor models6569
AHRI certifications8789

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardAIR-CONZERO
CEE 2025 Tier 1 (Split ASHP)55.4%36 models59.4%41 models
CEE 2026 Tier 1 (Split ASHP)55.4%36 models55.1%38 models
CEE Advanced Tier (Split ASHP)0%0 models0%0 models
Xcel Energy Colorado cold-climate ASHP (2025)49.2%32 models47.8%33 models
DOE Cold Climate Heat Pump Challenge0%0 models0%0 models
ENERGY STAR Cold Climate38.5%25 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
  • AIR-CON
  • 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 modelsNon-ducted, 5 tons and up2.1032 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 typeAIR-CONZERO
Ducted, up to 1.5 tons5 · index 49%2 · index 59%
Ducted, 2 tons6 · index 53%5 · index 69%
Ducted, 2.5–3 tons9 · index 56%7 · index 57%
Ducted, 3.5–4.5 tons11 · index 55%9 · index 63%
Ducted, 5 tons and up1 · index 52%1 · index 57%
Non-ducted, up to 1.5 tons27 · index 61%33 · index 48%
Non-ducted, 2 tons9 · index 52%9 · index 49%
Non-ducted, 2.5–3 tons8 · index 46%8 · index 39%
Non-ducted, 3.5–4.5 tons2 · index 53%3 · index 50%
Non-ducted, 5 tons and up1 · index 36%None

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 typeAIR-CONCold-climate score, best modelZEROCold-climate score, best model
Ducted, up to 1.5 tons51.6(50 is the typical model of its size class)ASLCI4H4S09with ducted air handler ASLEK4H4S093 of 5 models qualify · AHRI 20512951652.0(50 is the typical model of its size class) (higher)Z3SOV-18HDM-US1 of 2 models qualify · AHRI 214723150
Ducted, 2 tons64.8(50 is the typical model of its size class)ASLCI4H4S24with ducted air handler ASLEK4H4S243 of 6 models qualify · AHRI 20512952280.3(50 is the typical model of its size class) (higher)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models qualify · AHRI 212928560
Ducted, 2.5–3 tons78.1(50 is the typical model of its size class) (higher)ASLCI4H4S36with ducted air handler ASLEK4H4S364 of 9 models qualify · AHRI 20515042457.4(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 7 models qualify · AHRI 213732663
Ducted, 3.5–4.5 tons62.4(50 is the typical model of its size class)APIV4H4R044 of 11 models qualify · AHRI 21549389474.9(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US1 of 9 models qualify · AHRI 213732669
Ducted, 5 tons and upNone on this board (0 of 1 models qualify)None on this board (0 of 1 models qualify)
Non-ducted, up to 1.5 tons76.9(50 is the typical model of its size class)ASLCI4H4S09with ductless indoor unit ASLEC4H4S0919 of 27 models qualify · AHRI 20512951586.0(50 is the typical model of its size class) (higher)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH24 of 33 models qualify · AHRI 213917748
Non-ducted, 2 tons68.3(50 is the typical model of its size class)ASLCI4H4S24with ductless indoor unit ASLEC4H4S244 of 9 models qualify · AHRI 20512952174.2(50 is the typical model of its size class) (higher)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US4 of 9 models qualify · AHRI 212928564
Non-ducted, 2.5–3 tons77.2(50 is the typical model of its size class) (higher)ASLCI4H4S36with ductless indoor unit ASLEC4H4S362 of 8 models qualify · AHRI 20515042349.3(50 is the typical model of its size class)Z3SOV-27HDM-US1 of 8 models qualify · AHRI 213732662
Non-ducted, 3.5–4.5 tons42.4(50 is the typical model of its size class)AMSCI4H4S421 of 2 models qualify · AHRI 20515042680.5(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US2 of 3 models qualify · AHRI 213732668
Non-ducted, 5 tons and upNone on this board (0 of 1 models qualify)No models in this size class

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 typeAIR-CONAll-around score, best modelZEROAll-around score, best model
Ducted, up to 1.5 tons55.5(50 is the typical model of its size class)ASLCI4H4S09with ducted air handler ASLEK4H4S094 of 5 models have all five ratings · AHRI 20512951659.4(50 is the typical model of its size class) (higher)Z3SOV-18HDM-US1 of 2 models have all five ratings · AHRI 214723150
Ducted, 2 tons72.2(50 is the typical model of its size class)AMSCI4H4S244 of 6 models have all five ratings · AHRI 20446279883.8(50 is the typical model of its size class) (higher)ZSOV-24HDM-USwith ducted air handler ZDV-24HDM-US2 of 5 models have all five ratings · AHRI 212928560
Ducted, 2.5–3 tons77.7(50 is the typical model of its size class) (higher)AMSCI4H4S366 of 9 models have all five ratings · AHRI 20446279971.5(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 tons66.7(50 is the typical model of its size class)APIV4H4R046 of 11 models have all five ratings · AHRI 21549389482.0(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US2 of 9 models have all five ratings · AHRI 213732669
Ducted, 5 tons and up51.7(50 is the typical model of its size class)CH4H6C60KN-AE1 of 1 models have all five ratings · AHRI 21574627357.1(50 is the typical model of its size class) (higher)ZSOV-60HDM-USwith ducted air handler ZDV-60HDM-US1 of 1 models have all five ratings · AHRI 212928563
Non-ducted, up to 1.5 tons84.2(50 is the typical model of its size class)ABZCI4H4S09with ductless indoor unit ABZEM4H4S0921 of 27 models have all five ratings · AHRI 1027250086.7(50 is the typical model of its size class) (higher)ZMSB-09HV-USHHwith ductless indoor unit ZMSB-09HV-USHH33 of 33 models have all five ratings · AHRI 213917748
Non-ducted, 2 tons71.3(50 is the typical model of its size class)AMSCI4H4S247 of 9 models have all five ratings · AHRI 20446279472.0(50 is the typical model of its size class) (higher)ZSOV-24HDM-USwith ductless indoor unit ZEV-24HDM-US9 of 9 models have all five ratings · AHRI 212928564
Non-ducted, 2.5–3 tons68.1(50 is the typical model of its size class) (higher)AMSCI4H4S365 of 8 models have all five ratings · AHRI 20446279566.7(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 tons61.0(50 is the typical model of its size class)CH4H6C48KN-AE2 of 2 models have all five ratings · AHRI 21574626973.8(50 is the typical model of its size class) (higher)Z5SOV-48HDM-US3 of 3 models have all five ratings · AHRI 213732668
Non-ducted, 5 tons and up36.2(50 is the typical model of its size class)CH4H6C60KN-AE1 of 1 models have all five ratings · AHRI 215746270No models in this size class

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
RatingAIR-CONZERO
COP at 5°Fbeats 97% · 2.30CH4H6C36KN-AENon-ducted, 2.5–3 tonsbeats 96% · 2.22ZMSB-24HV-USHHNon-ducted, 2 tons
Capacity retention at 5°Fbeats 97% · 98%APIV4H4R04Ducted, 3.5–4.5 tonsbeats 84% · 87%Z5SOV-48HDM-USDucted, 3.5–4.5 tons
HSPF2beats 83% · 9.5ASLCI4H4S36Ducted, 2.5–3 tonsbeats 98% · 11.2ZSOV-24HDM-USDucted, 2 tons
SEER2beats 96% · 27.5ABZCI4H4S09Non-ducted, up to 1.5 tonsbeats 99% · 20.9Z5SOV-48HDM-USDucted, 3.5–4.5 tons
EER2beats 93% · 15.5ABZCI4H4S09Non-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 92% · 18,000 Btu/hAMSCI4H4S18Non-ducted, up to 1.5 tonsbeats 90% · 17,200 Btu/hZMSB-18HV-USHHCAlso listed as ZMSB-18HV-USHHC-ONon-ducted, up to 1.5 tons

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