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Panasonic vs WILLIS: heat pump ratings compared

Against heat pumps of the same size and type, a typical Panasonic model beats 68% and a typical WILLIS model 63%. Panasonic rates higher overall.

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

Panasonic

68%

of similar heat pumps beaten by its typical model

Well above average

29 models listed

WILLIS

63%

of similar heat pumps beaten by its typical model

Well above average

29 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°FPanasonic: Beats 64%WILLIS: Beats 44%
  • Heating power kept at 5°FCapacity at 5°F vs 47°FPanasonic: Beats 72%WILLIS: Beats 71%
  • Winter-long heating efficiencyHSPF2Panasonic: Beats 80%WILLIS: Beats 50%
  • Summer-long cooling efficiencySEER2Panasonic: Beats 66%WILLIS: Beats 69%
  • Hot-day cooling efficiencyEER2Panasonic: Beats 62%WILLIS: Beats 72%

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

    Panasonic
    97%
    WILLIS
    97%

  • Xcel CC

    Panasonic
    90%
    WILLIS
    97%

  • CEE Advanced

    Panasonic
    21%
    WILLIS
    10%

  • ENERGY STAR CC

    Panasonic
    79%
    WILLIS
    86%

All-around best, ductless 3.5–4.5 tons

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

Showing Ductless, 3.5–4.5 tons (39,000–56,999 Btu/h cooling). What size is my system?

Panasonic

  1. 1CU-6YM48CBUCPanasonic4 tons · 45,000 Btu/h · DuctlessCold-climate pick, score 68.7Meets CEE 2025, CEE 2026, Xcel CC
    Heat kept at 5°F
    98% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.00 (COP at 5°F)
    Below the middle
    Winter efficiency
    10.2 (HSPF2)
    Good
    Cooling efficiency
    21.2 (SEER2)
    Good
    Hot-day cooling
    12.0 (EER2)
    Good
    62.9score / 100Heating 63 · Cooling 63

WILLIS

  1. 1MZUHW42KR32-OWILLIS3.5 tons · 42,000 Btu/h · DuctlessCold-climate pick, score 66.5Meets 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
    2.10 (COP at 5°F)
    Great
    Winter efficiency
    10.0 (HSPF2)
    Below the middle
    Cooling efficiency
    21.0 (SEER2)
    Below the middle
    Hot-day cooling
    13.0 (EER2)
    Top 10%
    67.7score / 100Heating 67 · Cooling 69

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