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SLIMAIR vs Viessmann heat pumps

Measured against models of the same size and duct type, SLIMAIR and Viessmann split the 6 ratings 3–3. SLIMAIR has 48 outdoor models, Viessmann has 43 outdoor models. SLIMAIR and Viessmann 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.
SLIMAIR and Viessmann 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, SLIMAIR and Viessmann split the 6 ratings 3–3.
  • SLIMAIR
  • Viessmann
  • Other ranked manufacturers
SLIMAIRViessmann

Source: AHRI Directory, NEEP · as of

Average peer percentile, raw median and rank among ranked manufacturers
RatingSLIMAIRViessmann
Efficiency index60%median —60%median —
COP at 5°F60% (higher)median 2.0053% (higher)median 2.00
Capacity retention at 5°F59%median 78%72%median 88%
HSPF273%median 10.074%median 9.5
SEER261% (higher)median 19.559% (higher)median 17.0
EER253% (higher)median 11.749% (higher)median 11.0
Heating capacity at 5°F63%median 21,600 Btu/h74%median 25,000 Btu/h
Outdoor models4843
AHRI certifications117170

Share of models meeting each standard

Percent of each manufacturer’s models with a qualifying certification
StandardSLIMAIRViessmann
CEE 2025 Tier 1 (Split ASHP)89.6%43 models83.7%36 models
CEE 2026 Tier 1 (Split ASHP)87.5%42 models83.7%36 models
CEE Advanced Tier (Split ASHP)2.1%1 models4.7%2 models
Xcel Energy Colorado cold-climate ASHP (2025)77.1%37 models79.1%34 models
DOE Cold Climate Heat Pump Challenge2.1%1 models4.7%2 models
ENERGY STAR Cold Climate79.2%38 models69.8%30 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 · 8 groups where both have models
  • SLIMAIR
  • Viessmann
  • 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 typeSLIMAIRViessmann
Ducted, up to 1.5 tons11 · index 76%8 · index 67%
Ducted, 2 tons5 · index 67%7 · index 59%
Ducted, 2.5–3 tons9 · index 65%16 · index 55%
Ducted, 3.5–4.5 tons10 · index 61%11 · index 57%
Ducted, 5 tons and up2 · index 64%None
Non-ducted, up to 1.5 tons16 · index 61%5 · index 77%
Non-ducted, 2 tons4 · index 55%2 · index 79%
Non-ducted, 2.5–3 tons8 · index 49%6 · index 57%
Non-ducted, 3.5–4.5 tons7 · index 42%4 · index 52%
Non-ducted, 5 tons and up1 · index 27%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 typeSLIMAIRCold-climate score, best modelViessmannCold-climate score, best model
Ducted, up to 1.5 tons93.5(50 is the typical model of its size class) (higher)SHC06AH2AGwith ducted air handler SHDL06AC2AG10 of 11 models qualify · AHRI 21847298486.7(50 is the typical model of its size class)D5CUHAH18AAKwith ducted air handler D5MUWAQ18XA37 of 8 models qualify · AHRI 218668521
Ducted, 2 tons85.7(50 is the typical model of its size class)SHC24AH2AGwith ducted air handler SHD24AC2AG5 of 5 models qualify · AHRI 21669932785.7(50 is the typical model of its size class)D5CSHAH24AAKwith ducted air handler D5FSDAH24XHK7 of 7 models qualify · AHRI 217178805
Ducted, 2.5–3 tons83.2(50 is the typical model of its size class)SHC36AH2AGwith ducted air handler SHD36AC2AG7 of 9 models qualify · AHRI 21669932883.2(50 is the typical model of its size class)D5CMHAH36EAK11 of 16 models qualify · AHRI 217178827
Ducted, 3.5–4.5 tons82.7(50 is the typical model of its size class)SHC6Z48AH2AG10 of 10 models qualify · AHRI 21745629182.7(50 is the typical model of its size class)D5CMHAH48FAK10 of 11 models qualify · AHRI 217178830
Ducted, 5 tons and upNone on this board (0 of 2 models qualify)No models in this size class
Non-ducted, up to 1.5 tons93.8(50 is the typical model of its size class)SHC06AH2AGwith ductless indoor unit SHM06AE2AG12 of 16 models qualify · AHRI 21750025696.7(50 is the typical model of its size class) (higher)D5CSHAH06AAKwith ductless indoor unit D5FSHAH06XAK5 of 5 models qualify · AHRI 217178781
Non-ducted, 2 tons89.4(50 is the typical model of its size class)SHC24AH2AGwith ductless indoor unit SHL24AC2AG4 of 4 models qualify · AHRI 21669935189.4(50 is the typical model of its size class)D5CSHAH24AAKwith ductless indoor unit D5FSCAH24XAK2 of 2 models qualify · AHRI 217178803
Non-ducted, 2.5–3 tons89.4(50 is the typical model of its size class)SHC36AH2AGwith ductless indoor unit SHS36AC2AG6 of 8 models qualify · AHRI 21669934089.4(50 is the typical model of its size class)D5CLHAH36AAKwith ductless indoor unit D5FCFAH36XAK4 of 6 models qualify · AHRI 217178810
Non-ducted, 3.5–4.5 tons69.9(50 is the typical model of its size class)SHC6Z55AH2AG6 of 7 models qualify · AHRI 21745629575.5(50 is the typical model of its size class) (higher)D5CMHAH48FAK4 of 4 models qualify · AHRI 217178831
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 typeSLIMAIRAll-around score, best modelViessmannAll-around score, best model
Ducted, up to 1.5 tons95.0(50 is the typical model of its size class) (higher)SHC06AH2AGwith ducted air handler SHDL06AC2AG11 of 11 models have all five ratings · AHRI 21847298487.4(50 is the typical model of its size class)D5CSHAH09AAKwith ducted air handler D5FSDAH12XAK8 of 8 models have all five ratings · AHRI 217178787
Ducted, 2 tons78.8(50 is the typical model of its size class)SHC24AE2AGwith ducted air handler SHD24AC2AG5 of 5 models have all five ratings · AHRI 21669933480.0(50 is the typical model of its size class) (higher)D5CSHAH24AAKwith ducted air handler D5FSDAH24XHK7 of 7 models have all five ratings · AHRI 217178805
Ducted, 2.5–3 tons83.6(50 is the typical model of its size class)SHC5Z36AH2AG9 of 9 models have all five ratings · AHRI 21745628885.5(50 is the typical model of its size class) (higher)D5CMHAH30EAK16 of 16 models have all five ratings · AHRI 217178824
Ducted, 3.5–4.5 tons85.1(50 is the typical model of its size class) (higher)SHC6Z48AC2AG10 of 10 models have all five ratings · AHRI 21745627684.6(50 is the typical model of its size class)D5CMHAH48FAK11 of 11 models have all five ratings · AHRI 217178830
Ducted, 5 tons and up65.3(50 is the typical model of its size class)SHC60AC2AGwith ducted air handler SHD60AC2AG2 of 2 models have all five ratings · AHRI 216699337No models in this size class
Non-ducted, up to 1.5 tons93.8(50 is the typical model of its size class)SHC06AH2AGwith ductless indoor unit SHM06AE2AG16 of 16 models have all five ratings · AHRI 21750025696.5(50 is the typical model of its size class) (higher)D5CSHAH06AAKwith ductless indoor unit D5FSHAH06XAK5 of 5 models have all five ratings · AHRI 217178781
Non-ducted, 2 tons74.3(50 is the typical model of its size class)SHC24AE2AGwith ductless indoor unit SHM24AE2AG4 of 4 models have all five ratings · AHRI 21669931878.7(50 is the typical model of its size class) (higher)D5CSHAH24AAKwith ductless indoor unit D5FSHAH24XAK2 of 2 models have all five ratings · AHRI 217178802
Non-ducted, 2.5–3 tons66.3(50 is the typical model of its size class)SHC5Z36AH2AG8 of 8 models have all five ratings · AHRI 21745628785.8(50 is the typical model of its size class) (higher)D5CMHAH30EAK6 of 6 models have all five ratings · AHRI 217178823
Non-ducted, 3.5–4.5 tons62.6(50 is the typical model of its size class)SHC6Z55AH2AG7 of 7 models have all five ratings · AHRI 21745629376.7(50 is the typical model of its size class) (higher)D5CMHAH48FAK4 of 4 models have all five ratings · AHRI 217178829
Non-ducted, 5 tons and up32.5(50 is the typical model of its size class)SHC6Z55AC2AG1 of 1 models have all five ratings · AHRI 217456278No 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
RatingSLIMAIRViessmann
COP at 5°Fbeats 96% · 2.39SHC12AE2AGNon-ducted, up to 1.5 tonsbeats 97% · 2.40D5CSHAH06AAKNon-ducted, up to 1.5 tons
Capacity retention at 5°Fbeats 98% · 120%SHC09AH2AGDucted, up to 1.5 tonsbeats 100% · 116%D5CMHAH30EAKNon-ducted, 2.5–3 tons
HSPF2beats 99% · 11.0SHC6Z48AH2AGDucted, 3.5–4.5 tonsbeats 99% · 14.8D5CSHAH06AAKNon-ducted, up to 1.5 tons
SEER2beats 96% · 20.4SHC6Z48AC2AGDucted, 3.5–4.5 tonsbeats 99% · 20.5D5CMHAH48FAKDucted, 3.5–4.5 tons
EER2beats 99% · 14.4SHC06AH2AGDucted, up to 1.5 tonsbeats 99% · 18.0D5CSHAH06AAKNon-ducted, up to 1.5 tons
Heating capacity at 5°Fbeats 98% · 39,500 Btu/hSHC36AH2AGNon-ducted, 2.5–3 tonsbeats 98% · 19,600 Btu/hD5CUHAH18AAKDucted, up to 1.5 tons

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