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      18,000 BTU mini-split heat pump · Clivia

      TOSOT TWH18AUC25R32A1DO

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

      Ranks #59 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $475 a year to run in a mixed climate like Atlanta.

      SEER2
      24.5 Cooling efficiency over a season
      Very good · beats 79%
      HSPF2
      9.0 Heating efficiency over a season
      Below average · beats 10%
      EER2
      13.7 Cooling efficiency on a 95°F day
      Very good · beats 77%
      Heat at 5°F
      15,000 BTU/h81% of its 47°F output
      Below average · beats 27%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 79% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 15,000 BTU/h at 5°F.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You mainly need heat - its HSPF2 is below average for mini-splits.

      Calculate my running cost

      Details

      Specifications18,000 BTU, R-32
      General
      BrandTOSOT
      Outdoor unit modelTWH18AUC25R32A1DO
      SeriesClivia
      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 sinceMarch 20, 2024
      Last certifiedSeptember 22, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better24.5 (range 21.0-24.5)
      EER2Efficiency at 95°F outdoors12.6-14.0
      Cooling capacity18,000-21,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.0
      Capacity at 47°F18,000-21,000 BTU/h
      Capacity at 17°F14,700-18,000 BTU/h
      Capacity at 5°F14,600-15,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.90
      ENERGY STAR cold climateYes
      Heating output as it gets colder81% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with TWH18AUC25R32A1DI 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.
      TWH18AUC25R32A1DI · cold climate24.513.79.014,600218028410
      TM18R32SFDI · cold climate22.514.09.015,000218214176
      TM21R32SFDI · cold climate21.012.69.015,000218214177
      Yearly running cost in 10 large cities$349-$1,198

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

      Questions5
      What is the SEER2 rating of the TOSOT TWH18AUC25R32A1DO?
      The TOSOT TWH18AUC25R32A1DO is rated at up to 24.5 SEER2 and 13.7 EER2 for cooling and up to 9.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 3 certified matchups SEER2 ranges from 21.0-24.5.
      Is the TOSOT TWH18AUC25R32A1DO good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 15,000 BTU/h at 5°F with a COP of 1.90, so it is still 1.9 times as efficient as electric resistance heat at that temperature.
      How much does the TOSOT TWH18AUC25R32A1DO cost to run per year?
      At its rated efficiency it costs about $349-$1,198 a year in electricity in large U.S. cities, depending on climate and local rates - for example $467 in Phoenix and $1,029 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 TOSOT TWH18AUC25R32A1DO?
      ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use TWH18AUC25R32A1DI, TM18R32SFDI, TM21R32SFDI.
      What refrigerant does the TOSOT TWH18AUC25R32A1DO 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 $483/yrYou save $446/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 TOSOT TWH18AUC25R32A1DO
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $483
      Current system, per year
      $928
      You save per year
      $446
      Payback
      15.7 years
      Net after 10 years
      -$2,545

      Cooling $259Heating $224Electricity used: 3,016 kWhSaved vs. a minimum-efficiency heat pump: $229

      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 September 22, 2026. How we use the data.