What is the SEER2 rating of the MRCOOL O-HH-18-HP-C-230A?

The MRCOOL O-HH-18-HP-C-230A is rated at up to 21.5 SEER2 and 12.5 EER2 for cooling and up to 11.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.

Is the MRCOOL O-HH-18-HP-C-230A good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 18,000 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 MRCOOL O-HH-18-HP-C-230A cost to run per year?

At its rated efficiency it costs about $393-$1,015 a year in electricity in large U.S. cities, depending on climate and local rates - for example $479 in Phoenix and $844 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the MRCOOL O-HH-18-HP-C-230A the same as the MAXI AIR NE-T52-SUPAE18E?

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.

Which indoor units work with the MRCOOL O-HH-18-HP-C-230A?

ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses O-18-HP-WMAH-230B.

What refrigerant does the MRCOOL O-HH-18-HP-C-230A 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.

18,000 BTU mini-split heat pump · O-series

MRCOOL O-HH-18-HP-C-230A

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

Ranks #276 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $428 a year to run in a mixed climate like Atlanta.

SEER2: 21.5 Cooling efficiency over a season
Below average · beats 39%
HSPF2: 11.3 Heating efficiency over a season
Very good · beats 81%
EER2: 12.5 Cooling efficiency on a 95°F day
Average · beats 44%
Heat at 5°F: 18,000 BTU/h100% of its 47°F output
Below average · beats 9%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 18,000 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…

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
Brand	MRCOOL
Also sold as	MAXI AIR, SUPREME, QUEBEC VAIR
Outdoor unit model	O-HH-18-HP-C-230A
Series	O-series
Type	Mini-split heat pump
Nominal size	18,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-410A
Connected (smart) capable	No
On the market since	December 18, 2019
Last certified	June 29, 2026
Cooling
SEER2Seasonal efficiency, higher is better	21.5 (range 21.5)
EER2Efficiency at 95°F outdoors	12.5
Cooling capacity	18,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	11.3
Capacity at 47°F	18,000 BTU/h
Capacity at 17°F	15,000 BTU/h
Capacity at 5°F	18,000 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 colder100% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with O-18-HP-WMAH-230B at the standard test temperatures, in BTU/h:

Certified matchups2 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.
O-18-HP-WMAH-230B · cold climate	21.5	12.5	11.3	18,000	207339163
O-18-HP-WMAH-230B · cold climate	21.5	12.5	11.3	18,000	207339163

Same unit, other model numbers2

These model numbers have exactly the same certified ratings and matchups as the MRCOOL O-HH-18-HP-C-230A: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

MAXI AIR NE-T52-SUPAE18E
QUEBEC VAIR NE-T53-AEG18EXT

Yearly running cost in 10 large cities$393-$1,015

Phoenix, AZ$479/yr
Miami, FL$393/yr
Houston, TX$429/yr
Atlanta, GA$428/yr
Los Angeles, CA$415/yr
New York, NY$1,015/yr
Chicago, IL$822/yr
Denver, CO$683/yr
Seattle, WA$418/yr
Minneapolis, MN$844/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 MRCOOL O-HH-18-HP-C-230A?: The MRCOOL O-HH-18-HP-C-230A is rated at up to 21.5 SEER2 and 12.5 EER2 for cooling and up to 11.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
Is the MRCOOL O-HH-18-HP-C-230A good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 18,000 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 MRCOOL O-HH-18-HP-C-230A cost to run per year?: At its rated efficiency it costs about $393-$1,015 a year in electricity in large U.S. cities, depending on climate and local rates - for example $479 in Phoenix and $844 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the MRCOOL O-HH-18-HP-C-230A the same as the MAXI AIR NE-T52-SUPAE18E?: 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.
Which indoor units work with the MRCOOL O-HH-18-HP-C-230A?: ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses O-18-HP-WMAH-230B.
What refrigerant does the MRCOOL O-HH-18-HP-C-230A 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 $473/yrYou save $455/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 MRCOOL O-HH-18-HP-C-230A

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: $473
Current system, per year: $928
You save per year: $455
Payback: 15.4 years
Net after 10 years: -$2,450

Cooling $295Heating $178Electricity used: 2,957 kWhSaved vs. a minimum-efficiency heat pump: $239

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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Senville SENA/18HF/OQ · cold climate21.5 SEER2 · 11.3 HSPF2
Kepler ODUMOX430-17HFN1MT0W · cold climate21.5 SEER2 · 11.3 HSPF2
TRUST AIR CONDITIONERS OAH18H/O4S4P · cold climate21.5 SEER2 · 11.3 HSPF2
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Lennox MLB018S4S-1P · cold climate21.5 SEER2 · 11.2 HSPF2
Franklin MSH183E23MCAA · cold climate21.5 SEER2 · 11.3 HSPF2

See all 465 18,000 BTU mini-splits, ranked

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