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      Under 1.5-ton central heat pump · AT2239

      Atomi Smart AT2239

      Excellent cooling efficiency and below average heating efficiency for a under 1.5-ton central heat pump, but not rated for cold climates.

      Ranks #2 of 9 Under 1.5 ton central heat pumps for cooling efficiency, and costs about $355 a year to run in a mixed climate like Atlanta.

      SEER2
      23.9 Cooling efficiency over a season
      Excellent · beats 100%
      HSPF2
      8.3 Heating efficiency over a season
      Below average · beats 29%
      EER2
      13.1 Cooling efficiency on a 95°F day
      Excellent · beats 93%
      Heat at 5°F
      - Not reported by the maker

      A good fit if…

      • You want low cooling bills - its SEER2 beats 100% of central heat pumps.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You often see nights below 0°F - it is not cold-climate certified.
      • You mainly need heat - its HSPF2 is below average for central heat pumps.

      Calculate my running cost

      Details

      SpecificationsUnder 1.5 ton, R-32
      General
      BrandAtomi Smart
      Outdoor unit modelAT2239
      SeriesAT2239
      TypeCentral heat pump
      Nominal sizeUnder 1.5 ton
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-32
      Connected (smart) capableNo
      On the market sinceJanuary 1, 2025
      Last certifiedDecember 3, 2024
      Cooling
      SEER2Seasonal efficiency, higher is better23.9 (range 23.9)
      EER2Efficiency at 95°F outdoors13.1
      Cooling capacity12,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better8.3
      Capacity at 47°F12,749 BTU/h
      Capacity at 17°F6,722 BTU/h
      Capacity at 5°F-
      COP at 5°F2.0 = twice as efficient as a space heater-
      ENERGY STAR cold climateNo
      Heating output as it gets colder

      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 matchups1 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.
      -23.913.18.3--
      Yearly running cost in 10 large cities$240-$910

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

      Questions4
      What is the SEER2 rating of the Atomi Smart AT2239?
      The Atomi Smart AT2239 is rated at up to 23.9 SEER2 and 13.1 EER2 for cooling and up to 8.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Atomi Smart AT2239 good for cold climates?
      It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate under 1.5-ton model.
      How much does the Atomi Smart AT2239 cost to run per year?
      At its rated efficiency it costs about $240-$910 a year in electricity in large U.S. cities, depending on climate and local rates - for example $333 in Phoenix and $789 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      What refrigerant does the Atomi Smart AT2239 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 $350/yrYou save $281/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 Atomi Smart AT2239
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $350
      Current system, per year
      $631
      You save per year
      $281
      Payback
      16.0 years
      Net after 10 years
      -$1,688

      Cooling $177Heating $173Electricity used: 2,186 kWhSaved vs. a minimum-efficiency heat pump: $136

      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 Under 1.5 ton models

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      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of December 3, 2024. How we use the data.