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

      Mainline ML33HP230NEXH-O

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

      Ranks #123 of 171 30,000 BTU mini-splits for cooling efficiency, and costs about $892 a year to run in a mixed climate like Atlanta.

      SEER2
      20.0 Cooling efficiency over a season
      Below average · beats 18%
      HSPF2
      10.5 Heating efficiency over a season
      Average · beats 61%
      EER2
      11.7 Cooling efficiency on a 95°F day
      Below average · beats 16%
      Heat at 5°F
      34,600 BTU/h96% of its 47°F output
      Average · beats 48%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 34,600 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 modelML33HP230NEXH-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 19, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better20.0 (range 16.5-20.0)
      EER2Efficiency at 95°F outdoors11.7
      Cooling capacity33,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.0-10.5
      Capacity at 47°F35,000-36,000 BTU/h
      Capacity at 17°F27,400-31,000 BTU/h
      Capacity at 5°F34,000-34,600 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.91-2.00
      ENERGY STAR cold climateYes
      Heating output as it gets colder96% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ML33HP230NEX-I at the standard test temperatures, in BTU/h:

      Certified matchups4 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.
      ML33HP230NEX-I MAINLINE · cold climate20.011.710.534,600217607256
      ML33HP230NEX-I MAINLINE · cold climate20.011.710.534,600215864343
      ML36HP230AHU-I · cold climate16.511.710.034,000217607163
      ML36HP230AHU-I · cold climate16.511.710.034,000215864297
      Yearly running cost in 10 large cities$776-$2,148

      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 ML33HP230NEXH-O?
      The Mainline ML33HP230NEXH-O is rated at up to 20.0 SEER2 and 11.7 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 4 certified matchups SEER2 ranges from 16.5-20.0.
      Is the Mainline ML33HP230NEXH-O good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 34,600 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
      How much does the Mainline ML33HP230NEXH-O cost to run per year?
      At its rated efficiency it costs about $776-$2,148 a year in electricity in large U.S. cities, depending on climate and local rates - for example $967 in Phoenix and $1,802 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 ML33HP230NEXH-O?
      ENERGY STAR lists 4 certified combinations for this outdoor unit. The highest-rated ones use MAINLINE ML33HP230NEX-I, ML36HP230AHU-I.
      What refrigerant does the Mainline ML33HP230NEXH-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 $965/yrYou save $786/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 ML33HP230NEXH-O
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $965
      Current system, per year
      $1,751
      You save per year
      $786
      Payback
      15.9 years
      Net after 10 years
      -$4,642

      Cooling $581Heating $384Electricity used: 6,030 kWhSaved vs. a minimum-efficiency heat pump: $385

      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 August 19, 2026. How we use the data.