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      24,000 BTU mini-split heat pump · SZ Series

      Sea Breeze SZ24H424ZMO

      Below average cooling efficiency and very good heating efficiency for a 24,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #241 of 430 24,000 BTU mini-splits for cooling efficiency, and costs about $589 a year to run in a mixed climate like Atlanta.

      SEER2
      21.5 Cooling efficiency over a season
      Below average · beats 39%
      HSPF2
      11.2 Heating efficiency over a season
      Very good · beats 79%
      EER2
      12.5 Cooling efficiency on a 95°F day
      Average · beats 44%
      Heat at 5°F
      20,000 BTU/h74% 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 20,000 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 79% of mini-splits.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • Cooling cost matters most - its SEER2 is below average for mini-splits.
      • You want the newest refrigerant - it uses R-410A, which is being phased down.

      Calculate my running cost

      Details

      Specifications24,000 BTU, R-410A
      General
      BrandSea Breeze
      Outdoor unit modelSZ24H424ZMO
      SeriesSZ Series
      TypeMini-split heat pump
      Nominal size24,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-410A
      Connected (smart) capableNo
      On the market sinceFebruary 28, 2024
      Last certifiedApril 22, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better21.5 (range 18.0-21.5)
      EER2Efficiency at 95°F outdoors11.7-13.0
      Cooling capacity23,000-24,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better8.1-11.2
      Capacity at 47°F24,000-26,000 BTU/h
      Capacity at 17°F16,000-20,000 BTU/h
      Capacity at 5°F14,000-20,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.90-2.30
      ENERGY STAR cold climateYes
      Heating output as it gets colder74% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with CA24H424ZMI 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.
      CA24H424ZMI SEA BREEZE+ · cold climate21.512.59.718,500208128273
      FC24H424ZMI SEA BREEZE+ · cold climate21.212.510.318,200208128281
      WM24H424ZMI SEA BREEZE+21.013.08.516,700208128265
      D24H424ZMI SEA BREEZE+ · cold climate19.012.511.220,000208128279
      AH24H424ZMI18.011.78.114,000208128300
      Yearly running cost in 10 large cities$525-$1,409

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

      Questions5
      What is the SEER2 rating of the Sea Breeze SZ24H424ZMO?
      The Sea Breeze SZ24H424ZMO is rated at up to 21.5 SEER2 and 12.5 EER2 for cooling and up to 11.2 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 5 certified matchups SEER2 ranges from 18.0-21.5.
      Is the Sea Breeze SZ24H424ZMO good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 20,000 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 Sea Breeze SZ24H424ZMO cost to run per year?
      At its rated efficiency it costs about $525-$1,409 a year in electricity in large U.S. cities, depending on climate and local rates - for example $648 in Phoenix and $1,177 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 Sea Breeze SZ24H424ZMO?
      ENERGY STAR lists 5 certified combinations for this outdoor unit. The highest-rated ones use SEA BREEZE+ CA24H424ZMI, SEA BREEZE+ FC24H424ZMI, SEA BREEZE+ WM24H424ZMI.
      What refrigerant does the Sea Breeze SZ24H424ZMO use?
      It uses R-410A. R-410A is being phased down under the EPA AIM Act, and new systems are moving to R-454B and 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 $643/yrYou save $611/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 Sea Breeze SZ24H424ZMO
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $643
      Current system, per year
      $1,254
      You save per year
      $611
      Payback
      14.7 years
      Net after 10 years
      -$2,891

      Cooling $393Heating $250Electricity used: 4,018 kWhSaved vs. a minimum-efficiency heat pump: $321

      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.