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Top cold-climate picks by size

Heat pumps that keep most of their heat when it is 5°F outside, ranked on three ratings at once against units their size: how much heat they keep, how efficient they are at 5°F, and how efficient they are over a whole winter (HSPF2).

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

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

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.

497 of 569 models in this size class qualify. 69 keep less than 70% of their heat at 5°F and 2 have no 5°F heat output rating, so they cannot show it.

  1. 1KUMXA421ALG3.5 tons · 42,000 Btu/h · DuctlessKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP, ENERGY STAR CC
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.29 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    11.0 (HSPF2)
    Top 10%
    95.9score / 100
  2. 2AVW-48F3DAH2Hisense4 tons · 48,000 Btu/h · DuctlessKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.40 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    10.8 (HSPF2)
    Great
    94.6score / 100
  3. 3CHV6-RS48URBMHHCooper&Hunter (sold as Cooper & Hunter)4 tons · 48,000 Btu/h · DuctlessKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.40 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    10.8 (HSPF2)
    Great
    94.6score / 100
  4. 4KUSXA421Awith ductless indoor unit KNSCB421ALG3.5 tons · 42,000 Btu/h · DuctlessKeeps 91% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    91% (Capacity at 5°F vs 47°F)
    Great
    Efficiency at 5°F
    2.20 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    10.8 (HSPF2)
    Great
    88.6score / 100
  5. 5KUMXA481ALG4 tons · 48,000 Btu/h · DuctlessKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP, ENERGY STAR CC
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.34 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    10.5 (HSPF2)
    Good
    88.0score / 100
  6. 6ZRUM048GSS0LG4 tons · 48,000 Btu/h · DuctlessKeeps 100% of its heat at 5°FMeets CEE 2025, CEE 2026, CEE Advanced, Xcel CC, DOE CCHP, ENERGY STAR CC
    Heat kept at 5°F
    100% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.10 (COP at 5°F)
    Great
    Seasonal efficiency
    10.3 (HSPF2)
    Good
    80.2score / 100
  7. 7RAV-BP421AT2P-ULwith ductless indoor unit RAV-HB421CTP-ULCarrier (sold as Toshiba Carrier)3.5 tons · 42,000 Btu/h · DuctlessKeeps 79% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    79% (Capacity at 5°F vs 47°F)
    Below the middle
    Efficiency at 5°F
    2.20 (COP at 5°F)
    Top 10%
    Seasonal efficiency
    11.1 (HSPF2)
    Top 10%
    79.4score / 100
  8. 8MXZ-SM48NLHZ***Mitsubishi ElectricAlso listed as PUMY-HL48NKMU, MXZ-SM48NLHZ-4 tons · 48,000 Btu/h · DuctlessKeeps 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
    2.00 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    11.5 (HSPF2)
    Top 10%
    78.4score / 100
  9. 9MXZ-SM42NLHZ***Mitsubishi ElectricAlso listed as PUMY-HL42NKMU, MXZ-SM42NLHZ-3.5 tons · 42,000 Btu/h · DuctlessKeeps 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
    2.00 (COP at 5°F)
    Below the middle
    Seasonal efficiency
    11.1 (HSPF2)
    Top 10%
    77.6score / 100
  10. 10AOUH42KUAH1with ductless indoor unit AUUH42KUASFujitsu3.5 tons · 42,000 Btu/h · DuctlessKeeps 102% of its heat at 5°FMeets CEE 2025, CEE 2026, Xcel CC, ENERGY STAR CC
    Heat kept at 5°F
    102% (Capacity at 5°F vs 47°F)
    Top 10%
    Efficiency at 5°F
    2.02 (COP at 5°F)
    Good
    Seasonal efficiency
    10.6 (HSPF2)
    Good
    76.7score / 100

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

Want every qualifier’s peer percentiles and the all-sizes board? Switch to Advanced

What good looks like: ductless, 3.5–4.5 tons

Good is better than half of this size class, great is the top quarter, top is the top 10%. The scale comes from the class’s own ratings.

  • Capacity at 5°F vs 47°F

    Heating power kept at 5°F

    How much of its mild-weather heating power the unit still delivers at 5°F.

    Good
    81%+
    Great
    90%+
    Top 10%
    96%+

  • COP at 5°F

    Efficiency on a 5°F day

    How much heat the unit makes from each unit of electricity when it is 5°F outside.

    Good
    2.00+
    Great
    2.06+
    Top 10%
    2.11+

  • HSPF2

    Winter-long heating efficiency

    Heating efficiency over a whole winter, measured with a federal test.

    Good
    10.0+
    Great
    10.6+
    Top 10%
    11.0+

Next steps

The advanced view adds the all-sizes boards, each qualifier’s peer percentiles, charts of every model in each size class, and the EER2 and heat output boards.

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