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      2-ton central heat pump · AU Series

      AI AIR CONDITIONING AUO18-24N2-M3

      Very good cooling efficiency and excellent heating efficiency for a 2-ton central heat pump, and certified for cold climates.

      Ranks #134 of 331 2 ton central heat pumps for cooling efficiency, and costs about $658 a year to run in a mixed climate like Atlanta.

      SEER2
      18.1 Cooling efficiency over a season
      Very good · beats 71%
      HSPF2
      10.4 Heating efficiency over a season
      Excellent · beats 94%
      EER2
      11.0 Cooling efficiency on a 95°F day
      Below average · beats 23%
      Heat at 5°F
      21,600 BTU/h83% of its 47°F output
      Below average · beats 29%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 71% of central heat pumps.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 21,600 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 94% of central heat pumps.
      • 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

      Specifications2 ton, R-454B
      General
      BrandAI AIR CONDITIONING
      Outdoor unit modelAUO18-24N2-M3
      SeriesAU Series
      TypeCentral heat pump
      Nominal size2 ton
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceOctober 10, 2024
      Last certifiedMay 1, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better18.1 (range 16.0-18.1)
      EER2Efficiency at 95°F outdoors10.0-11.0
      Cooling capacity24,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.0-10.4
      Capacity at 47°F25,000-26,000 BTU/h
      Capacity at 17°F19,700-20,800 BTU/h
      Capacity at 5°F19,000-21,600 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.80-1.96
      ENERGY STAR cold climateYes
      Heating output as it gets colder83% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with AUH2-24N2-BM3E at the standard test temperatures, in BTU/h:

      Certified matchups5 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.
      AUH2-24N2-BM3E · cold climate18.111.09.721,600215866699
      AUE-24N2-MM3E · cold climate17.410.810.419,600217162338
      AUA-24N2-A18 · cold climate16.010.09.019,000217162319
      AUA-24N2-B18 · cold climate16.010.09.019,000217162320
      AUP-24N2-IM3 · cold climate16.010.09.019,000217162346
      Yearly running cost in 10 large cities$621-$1,547

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

      Questions5
      What is the SEER2 rating of the AI AIR CONDITIONING AUO18-24N2-M3?
      The AI AIR CONDITIONING AUO18-24N2-M3 is rated at up to 18.1 SEER2 and 11.0 EER2 for cooling and up to 10.4 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 5 certified matchups SEER2 ranges from 16.0-18.1.
      Is the AI AIR CONDITIONING AUO18-24N2-M3 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 21,600 BTU/h at 5°F with a COP of 1.96, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
      How much does the AI AIR CONDITIONING AUO18-24N2-M3 cost to run per year?
      At its rated efficiency it costs about $621-$1,547 a year in electricity in large U.S. cities, depending on climate and local rates - for example $750 in Phoenix and $1,280 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 AI AIR CONDITIONING AUO18-24N2-M3?
      ENERGY STAR lists 5 certified combinations for this outdoor unit. The highest-rated ones use AUH2-24N2-BM3E, AUE-24N2-MM3E, AUA-24N2-A18.
      What refrigerant does the AI AIR CONDITIONING AUO18-24N2-M3 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 $736/yrYou save $518/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 AUO18-24N2-M3
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $736
      Current system, per year
      $1,254
      You save per year
      $518
      Payback
      17.4 years
      Net after 10 years
      -$3,821

      Cooling $467Heating $269Electricity used: 4,600 kWhSaved vs. a minimum-efficiency heat pump: $228

      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 2 ton models

      See all 331 2 ton central heat pumps, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of May 1, 2026. How we use the data.