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SLIMAIR vs Viessmann: heat pump ratings compared

Against heat pumps of the same size and type, a typical SLIMAIR model beats 60% and a typical Viessmann model 60%. They are level.

Covers heat pumps sold new today (R-454B and R-32 refrigerant). See older R-410A models · Updated

SLIMAIR

60%

of similar heat pumps beaten by its typical model

Well above average

48 models listed

Viessmann

60%

of similar heat pumps beaten by its typical model

Well above average

43 models listed

Rating by ratingEach bar is the share of same-size, same-type heat pumps that a typical model beats, so the two brands compare fairly even if they make different sizes.
  • Efficiency on a 5°F dayCOP at 5°FSLIMAIR: Beats 60%Viessmann: Beats 53%
  • Heating power kept at 5°FCapacity at 5°F vs 47°FSLIMAIR: Beats 59%Viessmann: Beats 72%
  • Winter-long heating efficiencyHSPF2SLIMAIR: Beats 73%Viessmann: Beats 74%
  • Summer-long cooling efficiencySEER2SLIMAIR: Beats 61%Viessmann: Beats 59%
  • Hot-day cooling efficiencyEER2SLIMAIR: Beats 53%Viessmann: Beats 49%

Average (50%)Dashed outline: the other brand, for comparison

Want ranks, distributions per size class and cold-weather curves? Switch to Advanced

Rebate standards

Share of each brand’s models that meet the level. Programs can have other rules too.

  • CEE 2025

    SLIMAIR
    90%
    Viessmann
    84%

  • Xcel CC

    SLIMAIR
    77%
    Viessmann
    79%

  • CEE Advanced

    SLIMAIR
    2%
    Viessmann
    5%

  • ENERGY STAR CC

    SLIMAIR
    79%
    Viessmann
    70%

All-around best, ductless up to 1.5 tons

Balances heating (5°F output and efficiency, HSPF2) and cooling (SEER2, EER2), each rating against units their size.

Showing Ductless, Up to 1.5 tons (under 21,000 Btu/h cooling). What size is my system?

SLIMAIR

  1. 1SHC06AH2AGwith ductless indoor unit SHM06AE2AGSLIMAIR0.5 tons · 6,000 Btu/h · DuctlessCold-climate pick, score 93.8Meets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP, ENERGY STAR CC
    Heat kept at 5°F
    107% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.29 (COP at 5°F)
    Top 10%
    Winter efficiency
    14.6 (HSPF2)
    Top 10%
    Cooling efficiency
    25.3 (SEER2)
    Top 10%
    Hot-day cooling
    16.0 (EER2)
    Top 10%
    93.8score / 100Heating 94 · Cooling 94
  2. 2SHC09AE2AGwith ductless indoor unit SHM09AE2AGSLIMAIR1 ton · 9,000 Btu/h · DuctlessCold-climate pick, score 85.9Meets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    82% (Capacity at 5°F vs 47°F)
    Good
    Efficiency at 5°F
    2.33 (COP at 5°F)
    Top 10%
    Winter efficiency
    13.0 (HSPF2)
    Top 10%
    Cooling efficiency
    24.6 (SEER2)
    Great
    Hot-day cooling
    14.7 (EER2)
    Top 10%
    86.7score / 100Heating 86 · Cooling 87
  3. 3SHC09AH2AGwith ductless indoor unit SHM09AE2AGSLIMAIR1 ton · 9,000 Btu/h · DuctlessCold-climate pick, score 73.3Meets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    96% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    1.80 (COP at 5°F)
    Below the middle
    Winter efficiency
    12.5 (HSPF2)
    Top 10%
    Cooling efficiency
    26.0 (SEER2)
    Top 10%
    Hot-day cooling
    15.0 (EER2)
    Top 10%
    79.5score / 100Heating 65 · Cooling 94

Viessmann

  1. 1D5CSHAH06AAKwith ductless indoor unit D5FSHAH06XAKViessmann0.5 tons · 6,000 Btu/h · DuctlessCold-climate pick, score 96.7Meets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP, ENERGY STAR CC
    Heat kept at 5°F
    110% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.40 (COP at 5°F)
    Top 10%
    Winter efficiency
    14.8 (HSPF2)
    Top 10%
    Cooling efficiency
    25.7 (SEER2)
    Top 10%
    Hot-day cooling
    18.0 (EER2)
    Top 10%
    96.5score / 100Heating 97 · Cooling 96
  2. 2D5CSHAH09AAKwith ductless indoor unit D5FSFAH09XAKViessmann1 ton · 9,000 Btu/h · DuctlessCold-climate pick, score 73.6Meets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    126% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    1.84 (COP at 5°F)
    Below the middle
    Winter efficiency
    10.9 (HSPF2)
    Great
    Cooling efficiency
    27.3 (SEER2)
    Top 10%
    Hot-day cooling
    15.2 (EER2)
    Top 10%
    83.7score / 100Heating 72 · Cooling 96
  3. 3D5CMHAH18CAKViessmann1.5 tons · 19,000 Btu/h · DuctlessCold-climate pick, score 74.3Meets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    95% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    2.00 (COP at 5°F)
    Good
    Winter efficiency
    10.5 (HSPF2)
    Great
    Cooling efficiency
    25.0 (SEER2)
    Great
    Hot-day cooling
    15.0 (EER2)
    Top 10%
    82.5score / 100Heating 74 · Cooling 91

These are certified test ratings, not a recommendation for your home. The right size comes from a load calculation by a contractor.

Next steps

The advanced view adds ranks, both brands’ models inside every size class, standout models per rating and cold-weather curves.

Open the advanced view