HVAC Rated
    Menu

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

      Mitsubishi Electric MUZ-GS18NAH

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

      Ranks #283 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $522 a year to run in a mixed climate like Atlanta.

      SEER2
      21.5 Cooling efficiency over a season
      Below average · beats 39%
      HSPF2
      10.0 Heating efficiency over a season
      Average · beats 43%
      EER2
      13.5 Cooling efficiency on a 95°F day
      Very good · beats 72%
      Heat at 5°F
      14,700 BTU/h68% of its 47°F output
      Average · beats 59%

      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.
      • Cooling cost matters most - its SEER2 is below average for mini-splits.
      • 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
      Outdoor unit modelMUZ-GS18NAH
      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 sinceNovember 21, 2022
      Last certifiedMay 6, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better21.5 (range 21.5)
      EER2Efficiency at 95°F outdoors13.5
      Cooling capacity18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.0
      Capacity at 47°F21,600 BTU/h
      Capacity at 17°F13,300 BTU/h
      Capacity at 5°F14,700 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.04
      ENERGY STAR cold climateNo
      Heating output as it gets colder68% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with MSZ-GS18NA at the standard test temperatures, in BTU/h:

      Certified matchups1 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.
      MSZ-GS18NA21.513.510.014,700207679250
      Yearly running cost in 10 large cities$397-$1,304

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

      Questions5
      What is the SEER2 rating of the Mitsubishi Electric MUZ-GS18NAH?
      The Mitsubishi Electric MUZ-GS18NAH is rated at up to 21.5 SEER2 and 13.5 EER2 for cooling and up to 10.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Mitsubishi Electric MUZ-GS18NAH 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 MUZ-GS18NAH cost to run per year?
      At its rated efficiency it costs about $397-$1,304 a year in electricity in large U.S. cities, depending on climate and local rates - for example $523 in Phoenix and $1,116 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 Mitsubishi Electric MUZ-GS18NAH?
      ENERGY STAR lists 1 certified combination for this outdoor unit. The highest-rated one uses MSZ-GS18NA.
      What refrigerant does the Mitsubishi Electric MUZ-GS18NAH 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 $537/yrYou save $450/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 MUZ-GS18NAH
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $537
      Current system, per year
      $987
      You save per year
      $450
      Payback
      15.5 years
      Net after 10 years
      -$2,496

      Cooling $295Heating $242Electricity used: 3,354 kWhSaved vs. a minimum-efficiency heat pump: $229

      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 May 6, 2026. How we use the data.