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      12,000 BTU mini-split heat pump · KUSXB121A

      LG KUSXB121A

      Average cooling and heating efficiency for a 12,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #314 of 394 12,000 BTU mini-splits for cooling efficiency, and costs about $345 a year to run in a mixed climate like Atlanta.

      SEER2
      21.7 Cooling efficiency over a season
      Average · beats 42%
      HSPF2
      10.5 Heating efficiency over a season
      Average · beats 61%
      EER2
      12.2 Cooling efficiency on a 95°F day
      Below average · beats 33%
      Heat at 5°F
      11,400 BTU/h71% of its 47°F output
      Very good · beats 86%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 11,400 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

      Specifications12,000 BTU, R-32
      General
      BrandLG
      Outdoor unit modelKUSXB121A
      SeriesKUSXB121A
      TypeMini-split heat pump
      Nominal size12,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-32
      Connected (smart) capableNo
      On the market sinceApril 8, 2026
      Last certifiedApril 22, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better21.7 (range 16.4-21.7)
      EER2Efficiency at 95°F outdoors12.0-13.0
      Cooling capacity10,200-12,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.5-10.5
      Capacity at 47°F13,000-15,400 BTU/h
      Capacity at 17°F8,700-10,200 BTU/h
      Capacity at 5°F10,500-11,400 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.80-2.30
      ENERGY STAR cold climateYes
      Heating output as it gets colder71% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with KNUFB121A at the standard test temperatures, in BTU/h:

      Certified matchups6 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.
      KNUFB121A · cold climate21.712.210.111,000216778958
      KNUDB121A · cold climate21.513.010.110,700214826533
      KNUQB121A · cold climate19.713.010.511,400214825951
      KNSLB121A · cold climate17.012.29.510,500215588570
      KNSLB121A · cold climate17.012.29.510,500217284945
      KNUJB121A · cold climate16.412.010.511,000214826534
      Yearly running cost in 10 large cities$262-$863

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

      Questions5
      What is the SEER2 rating of the LG KUSXB121A?
      The LG KUSXB121A is rated at up to 21.7 SEER2 and 12.2 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 6 certified matchups SEER2 ranges from 16.4-21.7.
      Is the LG KUSXB121A good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 11,400 BTU/h at 5°F with a COP of 2.30, so it is still 2.3 times as efficient as electric resistance heat at that temperature.
      How much does the LG KUSXB121A cost to run per year?
      At its rated efficiency it costs about $262-$863 a year in electricity in large U.S. cities, depending on climate and local rates - for example $346 in Phoenix and $738 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 LG KUSXB121A?
      ENERGY STAR lists 6 certified combinations for this outdoor unit. The highest-rated ones use KNUFB121A, KNUDB121A, KNUQB121A.
      What refrigerant does the LG KUSXB121A 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 $355/yrYou save $313/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 LG KUSXB121A
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $355
      Current system, per year
      $668
      You save per year
      $313
      Payback
      14.4 years
      Net after 10 years
      -$1,368

      Cooling $195Heating $160Electricity used: 2,217 kWhSaved vs. a minimum-efficiency heat pump: $165

      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 April 22, 2026. How we use the data.