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      18,000 BTU mini-split heat pump · AO Series

      AI AIR CONDITIONING AO24-18N2-M1

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

      Ranks #61 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $368 a year to run in a mixed climate like Atlanta.

      SEER2
      24.0 Cooling efficiency over a season
      Very good · beats 75%
      HSPF2
      13.5 Heating efficiency over a season
      Excellent · beats 96%
      EER2
      13.5 Cooling efficiency on a 95°F day
      Very good · beats 74%
      Heat at 5°F
      14,200 BTU/h72% of its 47°F output
      Excellent · beats 93%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 75% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 14,200 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 96% 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-454B
      General
      BrandAI AIR CONDITIONING
      Also sold asMitsutomo, DuraSTAR, Multi MFG, Wells
      Outdoor unit modelAO24-18N2-M1
      SeriesAO Series
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceOctober 10, 2024
      Last certifiedMay 6, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better24.0 (range 18.5-24.0)
      EER2Efficiency at 95°F outdoors12.1-13.5
      Cooling capacity16,000-18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.8-13.5
      Capacity at 47°F17,000-20,000 BTU/h
      Capacity at 17°F13,200-15,000 BTU/h
      Capacity at 5°F12,800-14,200 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.05-2.40
      ENERGY STAR cold climateYes
      Heating output as it gets colder72% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with AW25-18N2-M1 at the standard test temperatures, in BTU/h:

      Certified matchups8 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.
      AW25-18N2-M1 · cold climate24.013.511.113,000215866732
      AS-16N2-M1 · cold climate23.812.513.513,100215866765
      AF-18N2-M1 · cold climate22.312.510.412,800215866766
      A1C-18N2-M1 · cold climate22.212.512.213,100215866752
      AC-18N2-M1 · cold climate20.712.511.412,800215866746
      AH-18N2-M1 · cold climate20.013.311.314,200215866758
      AL-18N2-M1 · cold climate20.012.510.514,000215866755
      AAH-18N2-BM1 · cold climate18.512.19.813,000217162304
      Same unit, other model numbers4

      These model numbers have exactly the same certified ratings and matchups as the AI AIR CONDITIONING AO24-18N2-M1: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

      Yearly running cost in 10 large cities$351-$861

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

      Questions6
      What is the SEER2 rating of the AI AIR CONDITIONING AO24-18N2-M1?
      The AI AIR CONDITIONING AO24-18N2-M1 is rated at up to 24.0 SEER2 and 13.5 EER2 for cooling and up to 13.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 8 certified matchups SEER2 ranges from 18.5-24.0.
      Is the AI AIR CONDITIONING AO24-18N2-M1 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 2.40, so it is still 2.4 times as efficient as electric resistance heat at that temperature.
      How much does the AI AIR CONDITIONING AO24-18N2-M1 cost to run per year?
      At its rated efficiency it costs about $351-$861 a year in electricity in large U.S. cities, depending on climate and local rates - for example $422 in Phoenix and $711 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Is the AI AIR CONDITIONING AO24-18N2-M1 the same as the Mitsutomo RU-SZ18-LA-Q?
      Yes, as far as the certified ratings go. ENERGY STAR lists 5 model numbers with identical efficiency, capacity and matchups, which means the same outdoor unit sold under a different brand or with a minor variant code (voltage, colour or region). The full list is on this page.
      Which indoor units work with the AI AIR CONDITIONING AO24-18N2-M1?
      ENERGY STAR lists 8 certified combinations for this outdoor unit. The highest-rated ones use AW25-18N2-M1, AS-16N2-M1, AF-18N2-M1.
      What refrigerant does the AI AIR CONDITIONING AO24-18N2-M1 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 $413/yrYou save $515/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 AI AIR CONDITIONING AO24-18N2-M1
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $413
      Current system, per year
      $928
      You save per year
      $515
      Payback
      13.6 years
      Net after 10 years
      -$1,852

      Cooling $264Heating $149Electricity used: 2,583 kWhSaved vs. a minimum-efficiency heat pump: $299

      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.