What is the SEER2 rating of the MDV M3OX430-18HFN10-M1-D?

The MDV M3OX430-18HFN10-M1-D is rated at up to 25.1 SEER2 and 14.0 EER2 for cooling and up to 10.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 6 certified matchups SEER2 ranges from 20.0-25.1.

Is the MDV M3OX430-18HFN10-M1-D good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 14,600 BTU/h at 5°F with a COP of 2.30, so it is still 2.3 times as efficient as electric resistance heat at that temperature.

How much does the MDV M3OX430-18HFN10-M1-D cost to run per year?

At its rated efficiency it costs about $341-$1,143 a year in electricity in large U.S. cities, depending on climate and local rates - for example $452 in Phoenix and $980 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the MDV M3OX430-18HFN10-M1-D the same as the Mainline ML18HP230MUL-O?

Yes, as far as the certified ratings go. ENERGY STAR lists 3 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.

18,000 BTU mini-split heat pump · M3O Series

MDV M3OX430-18HFN10-M1-D

Very good cooling efficiency and average heating efficiency for a 18,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #27 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $455 a year to run in a mixed climate like Atlanta.

SEER2: 25.1 Cooling efficiency over a season
Very good · beats 85%
HSPF2: 10.0 Heating efficiency over a season
Average · beats 43%
EER2: 14.0 Cooling efficiency on a 95°F day
Very good · beats 82%
Heat at 5°F: 14,600 BTU/h71% of its 47°F output
Very good · beats 86%

A good fit if…

You want low cooling bills - its SEER2 beats 85% of mini-splits.
Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 14,600 BTU/h at 5°F.
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

Specifications18,000 BTU, R-454B

General
Brand	MDV
Also sold as	Mainline, 1HVAC, ACIQ
Outdoor unit model	M3OX430-18HFN10-M1-D
Series	M3O Series
Type	Mini-split heat pump
Nominal size	18,000 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	25.1 (range 20.0-25.1)
EER2Efficiency at 95°F outdoors	12.0-14.0
Cooling capacity	18,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	9.8-10.0
Capacity at 47°F	19,000 BTU/h
Capacity at 17°F	16,000 BTU/h
Capacity at 5°F	13,500-14,600 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	2.20-2.30
ENERGY STAR cold climate	Yes

Heating output as it gets colder71% 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	25.1	14.0	9.8	13,500	214861839
- · cold climate	23.0	12.5	10.0	13,500	214861854
- · cold climate	22.6	13.0	9.9	14,000	214861841
- · cold climate	21.5	12.3	10.0	14,000	214861856
- · cold climate	20.0	12.0	10.0	14,600	214861840
- · cold climate	20.0	12.0	10.0	14,600	214861855

Same unit, other model numbers2

These model numbers have exactly the same certified ratings and matchups as the MDV M3OX430-18HFN10-M1-D: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Mainline ML18HP230MUL-O
1HVAC ES-18Z-M3C

Yearly running cost in 10 large cities$341-$1,143

Phoenix, AZ$452/yr
Miami, FL$341/yr
Houston, TX$406/yr
Atlanta, GA$455/yr
Los Angeles, CA$453/yr
New York, NY$1,143/yr
Chicago, IL$938/yr
Denver, CO$789/yr
Seattle, WA$491/yr
Minneapolis, MN$980/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 M3OX430-18HFN10-M1-D?: The MDV M3OX430-18HFN10-M1-D is rated at up to 25.1 SEER2 and 14.0 EER2 for cooling and up to 10.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 6 certified matchups SEER2 ranges from 20.0-25.1.
Is the MDV M3OX430-18HFN10-M1-D good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 14,600 BTU/h at 5°F with a COP of 2.30, so it is still 2.3 times as efficient as electric resistance heat at that temperature.
How much does the MDV M3OX430-18HFN10-M1-D cost to run per year?: At its rated efficiency it costs about $341-$1,143 a year in electricity in large U.S. cities, depending on climate and local rates - for example $452 in Phoenix and $980 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the MDV M3OX430-18HFN10-M1-D the same as the Mainline ML18HP230MUL-O?: Yes, as far as the certified ratings go. ENERGY STAR lists 3 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 M3OX430-18HFN10-M1-D 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 $465/yrYou save $479/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 M3OX430-18HFN10-M1-D

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: $465
Current system, per year: $944
You save per year: $479
Payback: 14.6 years
Net after 10 years: -$2,207

Cooling $252Heating $213Electricity used: 2,908 kWhSaved vs. a minimum-efficiency heat pump: $262

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

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Sharp AE-X18CHU · cold climate25.0 SEER2 · 11.5 HSPF2
Hitachi PAS-18BUFASDQ1 · cold climate25.0 SEER2 · 11.0 HSPF2
Bryant 37MGRAQ18CA3 · cold climate25.2 SEER2 · 10.0 HSPF2
York YPAS18BUFASDQ1 · cold climate25.0 SEER2 · 11.0 HSPF2
Arcoaire D5CMRAH18CAK · cold climate25.2 SEER2 · 10.0 HSPF2
Arcoaire D5CMHAH18CAK · cold climate25.0 SEER2 · 10.5 HSPF2
Mitsubishi Electric MUZ-FX18NLHZ · cold climate25.5 SEER2 · 11.1 HSPF2

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.