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      18,000 BTU mini-split heat pump · AIRSTAGE H-Series

      Fujitsu AOUH18KZAH1

      Very good cooling efficiency and excellent heating efficiency for a 18,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #20 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $425 a year to run in a mixed climate like Atlanta.

      SEER2
      25.5 Cooling efficiency over a season
      Very good · beats 88%
      HSPF2
      12.5 Heating efficiency over a season
      Excellent · beats 93%
      EER2
      14.0 Cooling efficiency on a 95°F day
      Very good · beats 82%
      Heat at 5°F
      24,800 BTU/h115% of its 47°F output
      Average · beats 62%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 88% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 24,800 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 93% of mini-splits.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • Nothing stands out - its ratings have no weak spot for its class.

      Calculate my running cost

      Details

      Specifications18,000 BTU, R-32
      General
      BrandFujitsu
      Outdoor unit modelAOUH18KZAH1
      SeriesAIRSTAGE H-Series
      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 sinceOctober 4, 2024
      Last certifiedApril 17, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better25.5 (range 25.5)
      EER2Efficiency at 95°F outdoors14.0
      Cooling capacity18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better12.5
      Capacity at 47°F21,600 BTU/h
      Capacity at 17°F13,600 BTU/h
      Capacity at 5°F24,800 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.08
      ENERGY STAR cold climateYes
      Heating output as it gets colder115% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ASUH18KZAS 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.
      ASUH18KZAS FUJITSU · cold climate25.514.012.524,800215647921
      ASUH18KZBS FUJITSU · cold climate25.514.012.524,800218381296
      Yearly running cost in 10 large cities$334-$1,052

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

      Questions5
      What is the SEER2 rating of the Fujitsu AOUH18KZAH1?
      The Fujitsu AOUH18KZAH1 is rated at up to 25.5 SEER2 and 14.0 EER2 for cooling and up to 12.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Fujitsu AOUH18KZAH1 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 24,800 BTU/h at 5°F with a COP of 2.08, so it is still 2.1 times as efficient as electric resistance heat at that temperature.
      How much does the Fujitsu AOUH18KZAH1 cost to run per year?
      At its rated efficiency it costs about $334-$1,052 a year in electricity in large U.S. cities, depending on climate and local rates - for example $434 in Phoenix and $896 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 Fujitsu AOUH18KZAH1?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated ones use FUJITSU ASUH18KZAS, FUJITSU ASUH18KZBS.
      What refrigerant does the Fujitsu AOUH18KZAH1 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 $442/yrYou save $545/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 Fujitsu AOUH18KZAH1
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $442
      Current system, per year
      $987
      You save per year
      $545
      Payback
      12.8 years
      Net after 10 years
      -$1,550

      Cooling $248Heating $194Electricity used: 2,763 kWhSaved vs. a minimum-efficiency heat pump: $324

      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.

      Similar 18,000 BTU models

      See all 465 18,000 BTU mini-splits, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of April 17, 2026. How we use the data.