What is the SEER2 rating of the Mitsubishi Electric MUZ-GS12NAHZ?

The Mitsubishi Electric MUZ-GS12NAHZ is rated at up to 21.7 SEER2 and 13.1 EER2 for cooling and up to 9.6 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.

Is the Mitsubishi Electric MUZ-GS12NAHZ good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 12,300 BTU/h at 5°F with a COP of 1.84, so it is still 1.8 times as efficient as electric resistance heat at that temperature.

How much does the Mitsubishi Electric MUZ-GS12NAHZ cost to run per year?

At its rated efficiency it costs about $261-$787 a year in electricity in large U.S. cities, depending on climate and local rates - for example $334 in Phoenix and $667 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the Mitsubishi Electric MUZ-GS12NAHZ the same as the Trane / Mitsubishi Electric NTXSSH12A112?

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 MUZ-GS12NAHZ?

ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use MSZ-GS12NA, American Standard / Mitsubishi Electric NAXWST12B112, Trane / Mitsubishi Electric NTXWST12B112.

What refrigerant does the Mitsubishi Electric MUZ-GS12NAHZ 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.

12,000 BTU mini-split heat pump · M-Series

Mitsubishi Electric MUZ-GS12NAHZ

Average cooling efficiency and below average heating efficiency for a 12,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #316 of 394 12,000 BTU mini-splits for cooling efficiency, and costs about $321 a year to run in a mixed climate like Atlanta.

SEER2: 21.7 Cooling efficiency over a season
Average · beats 42%
HSPF2: 9.6 Heating efficiency over a season
Below average · beats 30%
EER2: 13.1 Cooling efficiency on a 95°F day
Average · beats 68%
Heat at 5°F: 12,300 BTU/h100% of its 47°F output
Below average · beats 18%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 12,300 BTU/h at 5°F.
You want steady temperatures and quiet running - the compressor varies its speed.

Think twice if…

You mainly need heat - its HSPF2 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

Specifications12,000 BTU, R-410A

General
Brand	Mitsubishi Electric
Also sold as	American Standard / Mitsubishi Electric, Trane / Mitsubishi Electric
Outdoor unit model	MUZ-GS12NAHZ
Series	M-Series
Type	Mini-split heat pump
Nominal size	12,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-410A
Connected (smart) capable	No
On the market since	November 21, 2022
Last certified	March 13, 2025
Cooling
SEER2Seasonal efficiency, higher is better	21.7 (range 21.7)
EER2Efficiency at 95°F outdoors	13.1
Cooling capacity	12,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	9.6
Capacity at 47°F	12,300 BTU/h
Capacity at 17°F	7,600 BTU/h
Capacity at 5°F	12,300 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	1.84
ENERGY STAR cold climate	Yes

Heating output as it gets colder100% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with MSZ-GS12NA 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 unit	SEER2	EER2	HSPF2	Heat @5°F	AHRI ref.
MSZ-GS12NA · cold climate	21.7	13.1	9.6	12,300	207679253
NAXWST12B112 American Standard / Mitsubishi Electric · cold climate	21.7	13.1	9.6	12,300	207705500
NTXWST12B112 Trane / Mitsubishi Electric · cold climate	21.7	13.1	9.6	12,300	207705494

Same unit, other model numbers1

These model numbers have exactly the same certified ratings and matchups as the Mitsubishi Electric MUZ-GS12NAHZ: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Trane / Mitsubishi Electric NTXSSH12A112

Yearly running cost in 10 large cities$261-$787

Phoenix, AZ$334/yr
Miami, FL$261/yr
Houston, TX$300/yr
Atlanta, GA$321/yr
Los Angeles, CA$316/yr
New York, NY$787/yr
Chicago, IL$643/yr
Denver, CO$538/yr
Seattle, WA$333/yr
Minneapolis, MN$667/yr

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 MUZ-GS12NAHZ?: The Mitsubishi Electric MUZ-GS12NAHZ is rated at up to 21.7 SEER2 and 13.1 EER2 for cooling and up to 9.6 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
Is the Mitsubishi Electric MUZ-GS12NAHZ good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 12,300 BTU/h at 5°F with a COP of 1.84, so it is still 1.8 times as efficient as electric resistance heat at that temperature.
How much does the Mitsubishi Electric MUZ-GS12NAHZ cost to run per year?: At its rated efficiency it costs about $261-$787 a year in electricity in large U.S. cities, depending on climate and local rates - for example $334 in Phoenix and $667 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the Mitsubishi Electric MUZ-GS12NAHZ the same as the Trane / Mitsubishi Electric NTXSSH12A112?: 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 MUZ-GS12NAHZ?: ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use MSZ-GS12NA, American Standard / Mitsubishi Electric NAXWST12B112, Trane / Mitsubishi Electric NTXWST12B112.
What refrigerant does the Mitsubishi Electric MUZ-GS12NAHZ 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 $338/yrYou save $286/yrSee details ↓

1. Where you live

StateCityElectricity ¢ per kWh

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.

Cooling hours full-load hours per yearHeating hours full-load hours per year

2. The heat pump Mitsubishi Electric MUZ-GS12NAHZ

Find a model (fills in the ratings below)

SEER2 cooling efficiencyHSPF2 heating efficiencyCooling capacity BTU/hHeating capacity BTU/h

3. What it replaces

Current heatingFurnace efficiency (AFUE %)Gas price, $/thermCurrent coolingOld AC rating SEER2 (10 ≈ 15+ years old)

4. Price replace the example with your quote

Installed price, $Rebates and incentives, $ utility, state

Heat pump, per year: $338
Current system, per year: $624
You save per year: $286
Payback: 15.8 years
Net after 10 years: -$1,645

Cooling $195Heating $144Electricity used: 2,113 kWhSaved vs. a minimum-efficiency heat pump: $141

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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See all 394 12,000 BTU mini-splits, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of March 13, 2025. How we use the data.