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      42,000 BTU mini-split heat pump · DIY Series

      MRCOOL DIY-MULTI6-48HP230D-O

      Average cooling and heating efficiency for a 42,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #25 of 61 42,000 BTU mini-splits for cooling efficiency, and costs about $1,136 a year to run in a mixed climate like Atlanta.

      SEER2
      21.8 Cooling efficiency over a season
      Average · beats 44%
      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
      37,000 BTU/h77% 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 37,000 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

      Specifications42,000 BTU, R-454B
      General
      BrandMRCOOL
      Also sold asMDV, Blueridge
      Outdoor unit modelDIY-MULTI6-48HP230D-O
      SeriesDIY Series
      TypeMini-split heat pump
      Nominal size42,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceOctober 25, 2024
      Last certifiedMarch 4, 2025
      Cooling
      SEER2Seasonal efficiency, higher is better21.8 (range 20.0-21.8)
      EER2Efficiency at 95°F outdoors12.0
      Cooling capacity43,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.0-10.5
      Capacity at 47°F47,000-48,000 BTU/h
      Capacity at 17°F35,200-37,800 BTU/h
      Capacity at 5°F37,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.00
      ENERGY STAR cold climateYes
      Heating output as it gets colder77% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its best matchup 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.
      - · cold climate21.812.010.037,000216032595
      - · cold climate20.912.010.337,000216032597
      - · cold climate20.012.010.537,000216032596
      Same unit, other model numbers2

      These model numbers have exactly the same certified ratings and matchups as the MRCOOL DIY-MULTI6-48HP230D-O: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

      Yearly running cost in 10 large cities$932-$2,785

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

      Questions5
      What is the SEER2 rating of the MRCOOL DIY-MULTI6-48HP230D-O?
      The MRCOOL DIY-MULTI6-48HP230D-O is rated at up to 21.8 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; across its 3 certified matchups SEER2 ranges from 20.0-21.8.
      Is the MRCOOL DIY-MULTI6-48HP230D-O good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 37,000 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 MRCOOL DIY-MULTI6-48HP230D-O cost to run per year?
      At its rated efficiency it costs about $932-$2,785 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,189 in Phoenix and $2,358 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Is the MRCOOL DIY-MULTI6-48HP230D-O the same as the MDV M6OE30-48HFPN10-M1D?
      Yes, as far as the certified ratings go. ENERGY STAR lists 3 model numbers with identical efficiency, capacity and matchups, which means the same outdoor unit sold under a different brand or with a minor variant code (voltage, colour or region). The full list is on this page.
      What refrigerant does the MRCOOL DIY-MULTI6-48HP230D-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 $1,201/yrYou save $1,090/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 MRCOOL DIY-MULTI6-48HP230D-O
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,201
      Current system, per year
      $2,291
      You save per year
      $1,090
      Payback
      14.7 years
      Net after 10 years
      -$5,102

      Cooling $694Heating $507Electricity used: 7,506 kWhSaved vs. a minimum-efficiency heat pump: $567

      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 March 4, 2025. How we use the data.