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      18,000 BTU mini-split heat pump · 45M Series

      Carrier 37MARAQ18AA3

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

      Ranks #94 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $369 a year to run in a mixed climate like Atlanta.

      SEER2
      23.9 Cooling efficiency over a season
      Very good · beats 72%
      HSPF2
      13.5 Heating efficiency over a season
      Excellent · beats 96%
      EER2
      12.5 Cooling efficiency on a 95°F day
      Average · beats 44%
      Heat at 5°F
      14,200 BTU/h77% of its 47°F output
      Excellent · beats 93%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 72% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 14,200 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 96% of mini-splits.
      • 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

      Specifications18,000 BTU, R-454B
      General
      BrandCarrier
      Also sold asBryant, Payne, WeatherMaker, Midea
      Outdoor unit model37MARAQ18AA3
      Series45M Series
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceNovember 15, 2018
      Last certifiedJune 1, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better23.9 (range 18.5-23.9)
      EER2Efficiency at 95°F outdoors12.2-13.3
      Cooling capacity16,000-18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.8-13.5
      Capacity at 47°F17,000-20,000 BTU/h
      Capacity at 17°F13,200-15,000 BTU/h
      Capacity at 5°F12,800-14,200 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.05-2.40
      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 matchup with 45MBFAQ16XA3 at the standard test temperatures, in BTU/h:

      Certified matchups42 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.
      45MBFAQ16XA3 CARRIER · cold climate23.912.513.513,100215323829
      45MBFAQ16XA3 BRYANT · cold climate23.912.513.513,100215323890
      45MBFAQ16XA3 PAYNE · cold climate23.912.513.513,100215323951
      45MBFAQ16XA3 Weathermaker · cold climate23.912.513.513,100215324012
      45MBFAQ16XA3 MIDEA · cold climate23.912.513.513,100215324073
      45MAHAQ18XA3 CARRIER · cold climate23.512.810.812,800215323751
      615AHAQ18XA3 BRYANT · cold climate23.512.810.812,800215323762
      D5MAHAQ18XA3 PAYNE · cold climate23.512.810.812,800215323773
      D5MAHAQ18XA3 Weathermaker · cold climate23.512.810.812,800215323784
      D5MAHAQ18XA3 MIDEA · cold climate23.512.810.812,800215323795
      D5MAHAQ18XA3 BRYANT · cold climate23.512.810.812,800218139571
      D5MAHAQ18XA3 CARRIER · cold climate23.512.810.812,800218139558
      45MCFAQ18XA3 CARRIER · cold climate22.412.510.412,800215323830
      45MCFAQ18XA3 BRYANT · cold climate22.412.510.412,800215323891
      45MCFAQ18XA3 PAYNE · cold climate22.412.510.412,800215323952
      45MCFAQ18XA3 Weathermaker · cold climate22.412.510.412,800215324013
      45MCFAQ18XA3 MIDEA · cold climate22.412.510.412,800215324074
      45MCCAQ18XA3 CARRIER · cold climate22.312.512.213,100215323827
      45MCCAQ18XA3 BRYANT · cold climate22.312.512.213,100215323888
      45MCCAQ18XA3 PAYNE · cold climate22.312.512.213,100215323949
      45MCCAQ18XA3 Weathermaker · cold climate22.312.512.213,100215324010
      45MCCAQ18XA3 MIDEA · cold climate22.312.512.213,100215324071
      45MBCAQ18XA3 CARRIER · cold climate20.812.511.412,800215323828
      45MBCAQ18XA3 BRYANT · cold climate20.812.511.412,800215323889
      45MBCAQ18XA3 PAYNE · cold climate20.812.511.412,800215323950
      45MBCAQ18XA3 Weathermaker · cold climate20.812.511.412,800215324011
      45MBCAQ18XA3 MIDEA · cold climate20.812.511.412,800215324072
      45MBDAQ18XH3 CARRIER · cold climate20.013.311.414,200215323832
      45MBDAQ18XH3 BRYANT · cold climate20.013.311.414,200215323893
      45MBDAQ18XH3 PAYNE · cold climate20.013.311.414,200215323954
      45MBDAQ18XH3 Weathermaker · cold climate20.013.311.414,200215324015
      45MBDAQ18XH3 MIDEA · cold climate20.013.311.414,200215324076
      45MBDAQ18XA3 CARRIER · cold climate20.012.510.614,000215323831
      45MBDAQ18XA3 BRYANT · cold climate20.012.510.614,000215323892
      45MBDAQ18XA3 PAYNE · cold climate20.012.510.614,000215323953
      45MBDAQ18XA3 Weathermaker · cold climate20.012.510.614,000215324014
      45MBDAQ18XA3 MIDEA · cold climate20.012.510.614,000215324075
      45MBAAQ18XB3 · cold climate18.512.29.813,000215318795
      45MBAAQ18XB3 · cold climate18.512.29.813,000215318823
      45MBAAQ18XB3 · cold climate18.512.29.813,000215318851
      45MBAAQ18XB3 · cold climate18.512.29.813,000215318879
      45MBAAQ18XB3 · cold climate18.512.29.813,000215318767
      Yearly running cost in 10 large cities$352-$862

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

      Questions5
      What is the SEER2 rating of the Carrier 37MARAQ18AA3?
      The Carrier 37MARAQ18AA3 is rated at up to 23.9 SEER2 and 12.5 EER2 for cooling and up to 13.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 42 certified matchups SEER2 ranges from 18.5-23.9.
      Is the Carrier 37MARAQ18AA3 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 14,200 BTU/h at 5°F with a COP of 2.40, so it is still 2.4 times as efficient as electric resistance heat at that temperature.
      How much does the Carrier 37MARAQ18AA3 cost to run per year?
      At its rated efficiency it costs about $352-$862 a year in electricity in large U.S. cities, depending on climate and local rates - for example $424 in Phoenix and $712 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 Carrier 37MARAQ18AA3?
      ENERGY STAR lists 42 certified combinations for this outdoor unit. The highest-rated ones use CARRIER 45MBFAQ16XA3, BRYANT 45MBFAQ16XA3, PAYNE 45MBFAQ16XA3.
      What refrigerant does the Carrier 37MARAQ18AA3 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 $414/yrYou save $514/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 Carrier 37MARAQ18AA3
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $414
      Current system, per year
      $928
      You save per year
      $514
      Payback
      13.6 years
      Net after 10 years
      -$1,863

      Cooling $265Heating $149Electricity used: 2,590 kWhSaved vs. a minimum-efficiency heat pump: $297

      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 18,000 BTU models

      See all 465 18,000 BTU mini-splits, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of June 1, 2026. How we use the data.