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      42,000 BTU mini-split heat pump · P series

      Mitsubishi Electric PUZ-AK42NL

      Below average cooling efficiency and average heating efficiency for a 42,000 BTU mini-split heat pump, but not rated for cold climates.

      Ranks #34 of 61 42,000 BTU mini-splits for cooling efficiency, and costs about $1,180 a year to run in a mixed climate like Atlanta.

      SEER2
      21.0 Cooling efficiency over a season
      Below average · beats 30%
      HSPF2
      10.1 Heating efficiency over a season
      Average · beats 51%
      EER2
      12.0 Cooling efficiency on a 95°F day
      Below average · beats 25%
      Heat at 5°F
      25,400 BTU/h53% of its 47°F output
      Excellent · beats 99%

      A good fit if…

      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You often see nights below 0°F - it is not cold-climate certified.
      • Cooling cost matters most - its SEER2 is below average for mini-splits.

      Calculate my running cost

      Details

      Specifications42,000 BTU, R-454B
      General
      BrandMitsubishi Electric
      Outdoor unit modelPUZ-AK42NL
      SeriesP series
      TypeMini-split heat pump
      Nominal size42,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceNovember 1, 2023
      Last certifiedSeptember 9, 2025
      Cooling
      SEER2Seasonal efficiency, higher is better21.0 (range 18.7-21.0)
      EER2Efficiency at 95°F outdoors11.1-12.0
      Cooling capacity42,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.3-10.1
      Capacity at 47°F48,000 BTU/h
      Capacity at 17°F29,400-29,600 BTU/h
      Capacity at 5°F25,400 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.50-2.70
      ENERGY STAR cold climateNo
      Heating output as it gets colder53% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with PLA-AE42NL at the standard test temperatures, in BTU/h:

      Certified matchups3 indoor units

      The same outdoor unit scores differently with each indoor unit. Ask your installer for the AHRI reference number of the exact system you are quoted.

      Indoor unitSEER2EER2HSPF2Heat @5°FAHRI ref.
      PLA-AE42NL21.012.010.125,400215712195
      PVA-AA42NL19.111.19.425,400215712232
      PEAD-AA42NL18.711.19.325,400215712231
      Yearly running cost in 10 large cities$946-$2,908

      At each state's average electricity price and the city's typical heating and cooling hours.

      Questions5
      What is the SEER2 rating of the Mitsubishi Electric PUZ-AK42NL?
      The Mitsubishi Electric PUZ-AK42NL is rated at up to 21.0 SEER2 and 12.0 EER2 for cooling and up to 10.1 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 3 certified matchups SEER2 ranges from 18.7-21.0.
      Is the Mitsubishi Electric PUZ-AK42NL good for cold climates?
      It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 42,000 BTU model.
      How much does the Mitsubishi Electric PUZ-AK42NL cost to run per year?
      At its rated efficiency it costs about $946-$2,908 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,218 in Phoenix and $2,470 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Which indoor units work with the Mitsubishi Electric PUZ-AK42NL?
      ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use PLA-AE42NL, PVA-AA42NL, PEAD-AA42NL.
      What refrigerant does the Mitsubishi Electric PUZ-AK42NL use?
      It uses R-454B.

      Running cost and savings

      Pre-filled with this model. Pick your city and what you heat with today; everything else is optional.

      Heat pump $1,236/yrYou save $1,028/yrSee details ↓
      1. Where you live
      Adjust heating and cooling hours

      Filled in from your city's climate. Change them if you run the system much more or less than usual.

      2. The heat pump Mitsubishi Electric PUZ-AK42NL
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,236
      Current system, per year
      $2,264
      You save per year
      $1,028
      Payback
      15.6 years
      Net after 10 years
      -$5,725

      Cooling $704Heating $532Electricity used: 7,727 kWhSaved vs. a minimum-efficiency heat pump: $514

      Estimates use the unit's rated SEER2 and HSPF2, full-load hours derived from NOAA 1991-2020 degree days, average residential electricity prices from the U.S. EIA (12 months to July 2026) and fuel prices from EIA (2025 for natural gas, week of 2026-10-05 for propane and heating oil). Very cold days that need backup heat are not modelled. Federal minimum for comparison: 14.3 SEER2 / 7.5 HSPF2.

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      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of September 9, 2025. How we use the data.