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      30,000 BTU mini-split heat pump · ML Series

      Mainline ML33HP230CALH-O

      Below average cooling efficiency and average heating efficiency for a 30,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #143 of 171 30,000 BTU mini-splits for cooling efficiency, and costs about $900 a year to run in a mixed climate like Atlanta.

      SEER2
      19.5 Cooling efficiency over a season
      Below average · beats 12%
      HSPF2
      10.5 Heating efficiency over a season
      Average · beats 61%
      EER2
      12.0 Cooling efficiency on a 95°F day
      Below average · beats 25%
      Heat at 5°F
      35,000 BTU/h97% of its 47°F output
      Below average · beats 37%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 35,000 BTU/h at 5°F.
      • 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.

      Calculate my running cost

      Details

      Specifications30,000 BTU, R-454B
      General
      BrandMainline
      Outdoor unit modelML33HP230CALH-O
      SeriesML Series
      TypeMini-split heat pump
      Nominal size30,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceMay 20, 2024
      Last certifiedAugust 11, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better19.5 (range 19.5)
      EER2Efficiency at 95°F outdoors12.0
      Cooling capacity33,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.5
      Capacity at 47°F36,000 BTU/h
      Capacity at 17°F32,000 BTU/h
      Capacity at 5°F35,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.98
      ENERGY STAR cold climateYes
      Heating output as it gets colder97% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ML33HP230CALH-I at the standard test temperatures, in BTU/h:

      Certified matchups2 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.
      ML33HP230CALH-I MAINLINE · cold climate19.512.010.535,000217607262
      ML33HP230CALH-I MAINLINE · cold climate19.512.010.535,000215864349
      Yearly running cost in 10 large cities$796-$2,158

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

      Questions5
      What is the SEER2 rating of the Mainline ML33HP230CALH-O?
      The Mainline ML33HP230CALH-O is rated at up to 19.5 SEER2 and 12.0 EER2 for cooling and up to 10.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Mainline ML33HP230CALH-O good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 35,000 BTU/h at 5°F with a COP of 1.98, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
      How much does the Mainline ML33HP230CALH-O cost to run per year?
      At its rated efficiency it costs about $796-$2,158 a year in electricity in large U.S. cities, depending on climate and local rates - for example $985 in Phoenix and $1,806 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 Mainline ML33HP230CALH-O?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses MAINLINE ML33HP230CALH-I.
      What refrigerant does the Mainline ML33HP230CALH-O 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 $980/yrYou save $771/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 Mainline ML33HP230CALH-O
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $980
      Current system, per year
      $1,751
      You save per year
      $771
      Payback
      16.2 years
      Net after 10 years
      -$4,790

      Cooling $596Heating $384Electricity used: 6,123 kWhSaved vs. a minimum-efficiency heat pump: $370

      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 30,000 BTU models

      See all 171 30,000 BTU mini-splits, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of August 11, 2026. How we use the data.