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      18,000 BTU mini-split heat pump · airHome 400

      Hitachi RAC-DJ18WHAA

      Below average cooling efficiency and average heating efficiency for a 18,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #422 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $465 a year to run in a mixed climate like Atlanta.

      SEER2
      19.5 Cooling efficiency over a season
      Below average · beats 12%
      HSPF2
      10.5 Heating efficiency over a season
      Average · beats 61%
      EER2
      12.0 Cooling efficiency on a 95°F day
      Below average · beats 25%
      Heat at 5°F
      14,200 BTU/h79% of its 47°F output
      Below average · beats 27%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 14,200 BTU/h at 5°F.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • Cooling cost matters most - its SEER2 is below average for mini-splits.

      Calculate my running cost

      Details

      Specifications18,000 BTU, R-32
      General
      BrandHitachi
      Outdoor unit modelRAC-DJ18WHAA
      SeriesairHome 400
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-32
      Connected (smart) capableNo
      On the market sinceApril 28, 2026
      Last certifiedMay 6, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better19.5 (range 19.5)
      EER2Efficiency at 95°F outdoors12.0
      Cooling capacity18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.5
      Capacity at 47°F18,000 BTU/h
      Capacity at 17°F13,300 BTU/h
      Capacity at 5°F14,200 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.90
      ENERGY STAR cold climateYes
      Heating output as it gets colder79% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with RAK-DJ18PHAA at the standard test temperatures, in BTU/h:

      Certified matchups2 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.
      RAK-DJ18PHAA · cold climate19.512.010.514,200215224721
      RAK-DJ18RHAA · cold climate19.512.010.514,200216759657
      Yearly running cost in 10 large cities$433-$1,098

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

      Questions5
      What is the SEER2 rating of the Hitachi RAC-DJ18WHAA?
      The Hitachi RAC-DJ18WHAA is rated at up to 19.5 SEER2 and 12.0 EER2 for cooling and up to 10.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Hitachi RAC-DJ18WHAA good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 14,200 BTU/h at 5°F with a COP of 1.90, so it is still 1.9 times as efficient as electric resistance heat at that temperature.
      How much does the Hitachi RAC-DJ18WHAA cost to run per year?
      At its rated efficiency it costs about $433-$1,098 a year in electricity in large U.S. cities, depending on climate and local rates - for example $525 in Phoenix and $911 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 Hitachi RAC-DJ18WHAA?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated ones use RAK-DJ18PHAA, RAK-DJ18RHAA.
      What refrigerant does the Hitachi RAC-DJ18WHAA use?
      It uses R-32.

      Running cost and savings

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

      Heat pump $517/yrYou save $411/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 Hitachi RAC-DJ18WHAA
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $517
      Current system, per year
      $928
      You save per year
      $411
      Payback
      17.0 years
      Net after 10 years
      -$2,888

      Cooling $325Heating $192Electricity used: 3,231 kWhSaved vs. a minimum-efficiency heat pump: $195

      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 May 6, 2026. How we use the data.