What is the SEER2 rating of the Airtemp GXH24-36MSK4DH?

The Airtemp GXH24-36MSK4DH is rated at up to 17.0 SEER2 and 12.0 EER2 for cooling and up to 9.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 14 certified matchups SEER2 ranges from 16.0-17.0.

Is the Airtemp GXH24-36MSK4DH good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 28,000 BTU/h at 5°F with a COP of 1.80, so it is still 1.8 times as efficient as electric resistance heat at that temperature.

How much does the Airtemp GXH24-36MSK4DH cost to run per year?

At its rated efficiency it costs about $939-$2,467 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,152 in Phoenix and $2,057 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 Airtemp GXH24-36MSK4DH?

ENERGY STAR lists 14 certified combinations for this outdoor unit. The highest-rated ones use GMH24-**MSK4DH1, GMH**-36MSK4DH1.

What refrigerant does the Airtemp GXH24-36MSK4DH 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.

3-ton central heat pump · Ultra Side Discharge

Airtemp GXH24-36MSK4DH

Average cooling and heating efficiency for a 3-ton central heat pump, and certified for cold climates.

Ranks #156 of 302 3 ton central heat pumps for cooling efficiency, and costs about $1,036 a year to run in a mixed climate like Atlanta.

SEER2: 17.0 Cooling efficiency over a season
Average · beats 49%
HSPF2: 9.0 Heating efficiency over a season
Average · beats 54%
EER2: 12.0 Cooling efficiency on a 95°F day
Average · beats 64%
Heat at 5°F: 28,000 BTU/h92% of its 47°F output
Below average · beats 5%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 28,000 BTU/h at 5°F.
You want steady temperatures and quiet running - the compressor varies its speed.
You want a choice of indoor units - 14 certified pairings.

Think twice if…

You want the newest refrigerant - it uses R-410A, which is being phased down.

Calculate my running cost

Details

Specifications3 ton, R-410A

General
Brand	Airtemp
Also sold as	Gibson, Frigidaire, NORTEK, MAMMOTH, AireForce, REZNOR
Outdoor unit model	GXH24-36MSK4DH
Series	Ultra Side Discharge
Type	Central heat pump
Nominal size	3 ton
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-410A
Connected (smart) capable	No
On the market since	May 2, 2021
Last certified	June 29, 2026
Cooling
SEER2Seasonal efficiency, higher is better	17.0 (range 16.0-17.0)
EER2Efficiency at 95°F outdoors	10.0-12.0
Cooling capacity	24,000-34,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	9.0
Capacity at 47°F	24,000-35,000 BTU/h
Capacity at 17°F	20,000-29,000 BTU/h
Capacity at 5°F	22,000-28,000 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	1.80
ENERGY STAR cold climate	Yes

Heating output as it gets colder92% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with GMH24-**MSK4DH1 at the standard test temperatures, in BTU/h:

Certified matchups14 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.
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	208127838
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	206724408
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	208127840
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	206724396
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	206724412
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	206724404
GMH24-**MSK4DH1 · cold climate	17.0	12.0	9.0	22,000	206724400
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	206724409
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	208127828
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	206724405
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	206724397
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	206724401
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	206724413
GMH**-36MSK4DH1 · cold climate	16.0	10.0	9.0	28,000	208127834

Yearly running cost in 10 large cities$939-$2,467

Phoenix, AZ$1,152/yr
Miami, FL$939/yr
Houston, TX$1,032/yr
Atlanta, GA$1,036/yr
Los Angeles, CA$1,007/yr
New York, NY$2,467/yr
Chicago, IL$2,001/yr
Denver, CO$1,662/yr
Seattle, WA$1,020/yr
Minneapolis, MN$2,057/yr

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

Questions5

What is the SEER2 rating of the Airtemp GXH24-36MSK4DH?: The Airtemp GXH24-36MSK4DH is rated at up to 17.0 SEER2 and 12.0 EER2 for cooling and up to 9.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 14 certified matchups SEER2 ranges from 16.0-17.0.
Is the Airtemp GXH24-36MSK4DH good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 28,000 BTU/h at 5°F with a COP of 1.80, so it is still 1.8 times as efficient as electric resistance heat at that temperature.
How much does the Airtemp GXH24-36MSK4DH cost to run per year?: At its rated efficiency it costs about $939-$2,467 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,152 in Phoenix and $2,057 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 Airtemp GXH24-36MSK4DH?: ENERGY STAR lists 14 certified combinations for this outdoor unit. The highest-rated ones use GMH24-**MSK4DH1, GMH**-36MSK4DH1.
What refrigerant does the Airtemp GXH24-36MSK4DH 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 $1,140/yrYou save $630/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 Airtemp GXH24-36MSK4DH

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: $1,140
Current system, per year: $1,769
You save per year: $630
Payback: 20.6 years
Net after 10 years: -$6,701

Cooling $704Heating $436Electricity used: 7,122 kWhSaved vs. a minimum-efficiency heat pump: $220

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 302 3 ton central heat pumps, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of June 29, 2026. How we use the data.