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

      Mitsubishi Electric MUFZ-KJ18NAHZ

      Average cooling and heating efficiency for a 18,000 BTU mini-split heat pump, but not rated for cold climates.

      Ranks #214 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $489 a year to run in a mixed climate like Atlanta.

      SEER2
      22.0 Cooling efficiency over a season
      Average · beats 48%
      HSPF2
      10.3 Heating efficiency over a season
      Average · beats 55%
      EER2
      12.6 Cooling efficiency on a 95°F day
      Average · beats 52%
      Heat at 5°F
      - Not reported by the maker

      A good fit if…

      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You often see nights below 0°F - it is not cold-climate certified.
      • You want the newest refrigerant - it uses R-410A, which is being phased down.

      Calculate my running cost

      Details

      Specifications18,000 BTU, R-410A
      General
      BrandMitsubishi Electric
      Also sold asTrane / Mitsubishi Electric
      Outdoor unit modelMUFZ-KJ18NAHZ
      SeriesM-Series
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-410A
      Connected (smart) capableNo
      On the market sinceDecember 1, 2022
      Last certifiedJanuary 16, 2024
      Cooling
      SEER2Seasonal efficiency, higher is better22.0 (range 22.0)
      EER2Efficiency at 95°F outdoors12.6
      Cooling capacity17,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.3
      Capacity at 47°F21,000 BTU/h
      Capacity at 17°F12,800 BTU/h
      Capacity at 5°F-
      COP at 5°F2.0 = twice as efficient as a space heater-
      ENERGY STAR cold climateNo
      Heating output as it gets colder

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with NTXFKS18A112A 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.
      NTXFKS18A112A22.012.610.3-204629180
      NAXFKS18A112A22.012.610.3-204629575
      MFZ-KJ18NA22.012.610.3-210819448
      Same unit, other model numbers1

      These model numbers have exactly the same certified ratings and matchups as the Mitsubishi Electric MUFZ-KJ18NAHZ: 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$367-$1,227

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

      Questions6
      What is the SEER2 rating of the Mitsubishi Electric MUFZ-KJ18NAHZ?
      The Mitsubishi Electric MUFZ-KJ18NAHZ is rated at up to 22.0 SEER2 and 12.6 EER2 for cooling and up to 10.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Mitsubishi Electric MUFZ-KJ18NAHZ good for cold climates?
      It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 18,000 BTU model.
      How much does the Mitsubishi Electric MUFZ-KJ18NAHZ cost to run per year?
      At its rated efficiency it costs about $367-$1,227 a year in electricity in large U.S. cities, depending on climate and local rates - for example $486 in Phoenix and $1,051 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Is the Mitsubishi Electric MUFZ-KJ18NAHZ the same as the Trane / Mitsubishi Electric NTXSPF18A112A?
      Yes, as far as the certified ratings go. ENERGY STAR lists both 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.
      Which indoor units work with the Mitsubishi Electric MUFZ-KJ18NAHZ?
      ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use NTXFKS18A112A, NAXFKS18A112A, MFZ-KJ18NA.
      What refrigerant does the Mitsubishi Electric MUFZ-KJ18NAHZ 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 $500/yrYou save $442/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 Mitsubishi Electric MUFZ-KJ18NAHZ
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $500
      Current system, per year
      $942
      You save per year
      $442
      Payback
      14.7 years
      Net after 10 years
      -$2,083

      Cooling $272Heating $228Electricity used: 3,127 kWhSaved vs. a minimum-efficiency heat pump: $232

      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 January 16, 2024. How we use the data.