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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%

Top cold-climate picks, ducted 2 tons

Only units that keep at least 70% of their heat at 5°F, ranked on heat kept, efficiency at 5°F and seasonal efficiency (HSPF2), against units their size.

Showing Ducted, 2 tons (21,000–26,999 Btu/h cooling). What size is my system?

SLIMAIR

  1. 1SHC24AH2AGwith ducted air handler SHD24AC2AGSLIMAIR2 tons · 24,000 Btu/h · DuctedKeeps 92% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    92% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    2.18 (COP at 5°F)
    Good
    Seasonal efficiency
    11.7 (HSPF2)
    Top 10%
    85.7score / 100
  2. 2SHC24AE2AGwith ducted air handler SHD24AC2AGSLIMAIR2 tons · 24,000 Btu/h · DuctedKeeps 76% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    76% (Capacity at 5°F vs 47°F)
    Good
    Efficiency at 5°F
    2.30 (COP at 5°F)
    Great
    Seasonal efficiency
    11.0 (HSPF2)
    Top 10%
    77.1score / 100
  3. 3SHC24AH224Vwith ducted air handler SHV24AE2AGSLIMAIR2 tons · 23,000 Btu/h · DuctedKeeps 90% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    90% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    1.87 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    10.0 (HSPF2)
    Great
    66.3score / 100

Viessmann

  1. 1D5CSHAH24AAKwith ducted air handler D5FSDAH24XHKViessmann2 tons · 24,000 Btu/h · DuctedKeeps 92% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    92% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    2.18 (COP at 5°F)
    Good
    Seasonal efficiency
    11.7 (HSPF2)
    Top 10%
    85.7score / 100
  2. 2D5CUHAH24AAKwith ducted air handler D5FUHAH24XAKViessmann2 tons · 24,000 Btu/h · DuctedKeeps 86% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    86% (Capacity at 5°F vs 47°F)
    Good
    Efficiency at 5°F
    2.14 (COP at 5°F)
    Good
    Seasonal efficiency
    10.0 (HSPF2)
    Great
    75.8score / 100
  3. 3D5CMHAH24DAKViessmann2 tons · 24,000 Btu/h · DuctedKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    1.90 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    9.5 (HSPF2)
    Good
    68.1score / 100

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.

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