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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 59% and a typical Viessmann model 53%. SLIMAIR rates higher overall.

Covers older R-410A heat pumps, no longer installed new. See models sold today · Updated

SLIMAIR

59%

of similar heat pumps beaten by its typical model

Above average

54 models listed

Viessmann

53%

of similar heat pumps beaten by its typical model

About average

53 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 47%Viessmann: Beats 52%
  • Heating power kept at 5°FCapacity at 5°F vs 47°FSLIMAIR: Beats 58%Viessmann: Beats 50%
  • Winter-long heating efficiencyHSPF2SLIMAIR: Beats 71%Viessmann: Beats 63%
  • Summer-long cooling efficiencySEER2SLIMAIR: Beats 65%Viessmann: Beats 58%
  • Hot-day cooling efficiencyEER2SLIMAIR: Beats 49%Viessmann: Beats 46%

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
    67%
    Viessmann
    64%

  • Xcel CC

    SLIMAIR
    50%
    Viessmann
    43%

  • CEE Advanced

    SLIMAIR
    2%
    Viessmann
    4%

  • ENERGY STAR CC

    SLIMAIR
    43%
    Viessmann
    47%

Top cold-climate picks, ductless 3.5–4.5 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 Ductless, 3.5–4.5 tons (39,000–56,999 Btu/h cooling). What size is my system?

SLIMAIR

  1. 1SHC5Z48VE2AGSLIMAIR4 tons · 48,000 Btu/h · DuctlessKeeps 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
    2.00 (COP at 5°F)
    Good
    Seasonal efficiency
    10.0 (HSPF2)
    Great
    80.5score / 100
  2. 2SHC5Z55VE2AGSLIMAIR4.5 tons · 55,000 Btu/h · DuctlessKeeps 85% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    85% (Capacity at 5°F vs 47°F)
    Good
    Efficiency at 5°F
    1.77 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    9.5 (HSPF2)
    Below the middle
    38.9score / 100

Viessmann

  1. 1DLCMHBH48EAKViessmann4 tons · 48,000 Btu/h · DuctlessKeeps 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
    2.00 (COP at 5°F)
    Good
    Seasonal efficiency
    10.0 (HSPF2)
    Great
    80.5score / 100
  2. 2DLCLRCH48AAKwith ductless indoor unit DLFLFAH48XAKViessmann4 tons · 48,000 Btu/h · DuctlessKeeps 70% of its heat at 5°FMeets Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    70% (Capacity at 5°F vs 47°F)
    Below the middle
    Efficiency at 5°F
    1.85 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    10.0 (HSPF2)
    Great
    56.3score / 100
  3. 3DLCMTAH48EAKViessmann4 tons · 48,000 Btu/h · DuctlessKeeps 71% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    71% (Capacity at 5°F vs 47°F)
    Below the middle
    Efficiency at 5°F
    1.80 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    8.8 (HSPF2)
    Below the middle
    27.8score / 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.

Open the advanced view