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

      Fujitsu AOUH18KWAS2

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

      Ranks #212 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $508 a year to run in a mixed climate like Atlanta.

      SEER2
      22.0 Cooling efficiency over a season
      Average · beats 48%
      HSPF2
      10.5 Heating efficiency over a season
      Average · beats 61%
      EER2
      13.2 Cooling efficiency on a 95°F day
      Average · beats 69%
      Heat at 5°F
      17,000 BTU/h77% of its 47°F output
      Very good · beats 84%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 17,000 BTU/h at 5°F.
      • 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 modelAOUH18KWAS2
      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 sinceSeptember 21, 2024
      Last certifiedJune 23, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better22.0 (range 19.0-22.0)
      EER2Efficiency at 95°F outdoors12.7-13.2
      Cooling capacity18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.5-10.5
      Capacity at 47°F22,000 BTU/h
      Capacity at 17°F14,300-15,100 BTU/h
      Capacity at 5°F17,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.28
      ENERGY STAR cold climateYes
      Heating output as it gets colder77% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its best matchup 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.
      - FUJITSU · cold climate22.013.210.517,000215447685
      - FUJITSU · cold climate20.512.910.017,000215447695
      - FUJITSU · cold climate19.012.79.517,000215447686
      Yearly running cost in 10 large cities$388-$1,267

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

      Questions4
      What is the SEER2 rating of the Fujitsu AOUH18KWAS2?
      The Fujitsu AOUH18KWAS2 is rated at up to 22.0 SEER2 and 13.2 EER2 for cooling and up to 10.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 3 certified matchups SEER2 ranges from 19.0-22.0.
      Is the Fujitsu AOUH18KWAS2 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 17,000 BTU/h at 5°F with a COP of 2.28, so it is still 2.3 times as efficient as electric resistance heat at that temperature.
      How much does the Fujitsu AOUH18KWAS2 cost to run per year?
      At its rated efficiency it costs about $388-$1,267 a year in electricity in large U.S. cities, depending on climate and local rates - for example $510 in Phoenix and $1,083 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      What refrigerant does the Fujitsu AOUH18KWAS2 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 $523/yrYou save $471/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 AOUH18KWAS2
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $523
      Current system, per year
      $994
      You save per year
      $471
      Payback
      14.9 years
      Net after 10 years
      -$2,291

      Cooling $288Heating $235Electricity used: 3,267 kWhSaved vs. a minimum-efficiency heat pump: $249

      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

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      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of June 23, 2026. How we use the data.