What is the SEER2 rating of the MDV M5OX631-36HFN10-M1X?

The MDV M5OX631-36HFN10-M1X is rated at up to 23.1 SEER2 and 13.1 EER2 for cooling and up to 11.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 6 certified matchups SEER2 ranges from 19.5-23.1.

Is the MDV M5OX631-36HFN10-M1X good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 38,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.

How much does the MDV M5OX631-36HFN10-M1X cost to run per year?

At its rated efficiency it costs about $733-$2,002 a year in electricity in large U.S. cities, depending on climate and local rates - for example $909 in Phoenix and $1,677 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the MDV M5OX631-36HFN10-M1X the same as the MDV M5OX631-36HFN10-M1XD?

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.

36,000 BTU mini-split heat pump · M5O Series

MDV M5OX631-36HFN10-M1X

Average cooling efficiency and very good heating efficiency for a 36,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #30 of 205 36,000 BTU mini-splits for cooling efficiency, and costs about $833 a year to run in a mixed climate like Atlanta.

SEER2: 23.1 Cooling efficiency over a season
Average · beats 66%
HSPF2: 11.3 Heating efficiency over a season
Very good · beats 81%
EER2: 13.1 Cooling efficiency on a 95°F day
Average · beats 68%
Heat at 5°F: 38,000 BTU/h100% of its 47°F output
Average · beats 48%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 38,000 BTU/h at 5°F.
It will heat most of the year - its HSPF2 beats 81% 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

Specifications36,000 BTU, R-454B

General
Brand	MDV
Outdoor unit model	M5OX631-36HFN10-M1X
Series	M5O Series
Type	Mini-split heat pump
Nominal size	36,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-454B
Connected (smart) capable	No
On the market since	November 1, 2015
Last certified	May 6, 2026
Cooling
SEER2Seasonal efficiency, higher is better	23.1 (range 19.5-23.1)
EER2Efficiency at 95°F outdoors	12.0-13.1
Cooling capacity	36,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	10.5-11.3
Capacity at 47°F	36,000 BTU/h
Capacity at 17°F	38,000-38,500 BTU/h
Capacity at 5°F	36,000-38,000 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	1.90-2.00
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 best matchup at the standard test temperatures, in BTU/h:

Certified matchups6 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.
- · cold climate	23.1	13.1	10.7	36,000	214861785
- · cold climate	21.5	12.2	11.3	37,000	214861788
- · cold climate	21.3	12.6	10.6	37,000	214861787
- · cold climate	20.5	12.1	10.9	37,400	214861790
- · cold climate	19.5	12.0	10.5	38,000	214861786
- · cold climate	19.5	12.0	10.5	38,000	214861789

Same unit, other model numbers1

These model numbers have exactly the same certified ratings and matchups as the MDV M5OX631-36HFN10-M1X: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

MDV M5OX631-36HFN10-M1XD

Yearly running cost in 10 large cities$733-$2,002

Phoenix, AZ$909/yr
Miami, FL$733/yr
Houston, TX$815/yr
Atlanta, GA$833/yr
Los Angeles, CA$813/yr
New York, NY$2,002/yr
Chicago, IL$1,627/yr
Denver, CO$1,355/yr
Seattle, WA$834/yr
Minneapolis, MN$1,677/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 MDV M5OX631-36HFN10-M1X?: The MDV M5OX631-36HFN10-M1X is rated at up to 23.1 SEER2 and 13.1 EER2 for cooling and up to 11.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 6 certified matchups SEER2 ranges from 19.5-23.1.
Is the MDV M5OX631-36HFN10-M1X good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 38,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
How much does the MDV M5OX631-36HFN10-M1X cost to run per year?: At its rated efficiency it costs about $733-$2,002 a year in electricity in large U.S. cities, depending on climate and local rates - for example $909 in Phoenix and $1,677 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the MDV M5OX631-36HFN10-M1X the same as the MDV M5OX631-36HFN10-M1XD?: 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.
What refrigerant does the MDV M5OX631-36HFN10-M1X 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 $905/yrYou save $951/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 MDV M5OX631-36HFN10-M1X

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: $905
Current system, per year: $1,856
You save per year: $951
Payback: 14.2 years
Net after 10 years: -$3,991

Cooling $549Heating $357Electricity used: 5,659 kWhSaved vs. a minimum-efficiency heat pump: $518

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 36,000 BTU models

Mitsubishi Electric PUZ-AK36NLHZ · cold climate23.3 SEER2 · 9.7 HSPF2
Arcoaire D5CMHAH36EAK · cold climate23.1 SEER2 · 10.7 HSPF2
Mitsubishi Electric PUZ-AK36NL223.3 SEER2 · 9.8 HSPF2
Bryant 37MGHAQ36EA3 · cold climate23.1 SEER2 · 10.7 HSPF2
Mitsubishi Electric PUZ-AK36NL23.3 SEER2 · 9.8 HSPF2
Fujitsu AOUK036MSAN7 · cold climate23.1 SEER2 · 10.3 HSPF2
Mitsubishi Electric PUZ-AK36NLHZ2 · cold climate23.3 SEER2 · 10.5 HSPF2
AproDr AM5OG-36HFN1 · cold climate23.1 SEER2 · 10.0 HSPF2

See all 205 36,000 BTU mini-splits, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of May 6, 2026. How we use the data.