What is the SEER2 rating of the Mainline ML24HP230CALH-O?

The Mainline ML24HP230CALH-O is rated at up to 21.0 SEER2 and 13.0 EER2 for cooling and up to 13.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.

Is the Mainline ML24HP230CALH-O good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 24,200 BTU/h at 5°F with a COP of 2.34, so it is still 2.3 times as efficient as electric resistance heat at that temperature.

How much does the Mainline ML24HP230CALH-O cost to run per year?

At its rated efficiency it costs about $536-$1,372 a year in electricity in large U.S. cities, depending on climate and local rates - for example $652 in Phoenix and $1,140 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.

Is the Mainline ML24HP230CALH-O the same as the Continental CDHAS26BA-24-O?

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 Mainline ML24HP230CALH-O?

ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses MAINLINE ML24HP230CALH-I.

24,000 BTU mini-split heat pump · ML Series

Mainline ML24HP230CALH-O

Below average cooling efficiency and excellent heating efficiency for a 24,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #263 of 430 24,000 BTU mini-splits for cooling efficiency, and costs about $580 a year to run in a mixed climate like Atlanta.

SEER2: 21.0 Cooling efficiency over a season
Below average · beats 30%
HSPF2: 13.5 Heating efficiency over a season
Excellent · beats 96%
EER2: 13.0 Cooling efficiency on a 95°F day
Average · beats 62%
Heat at 5°F: 24,200 BTU/h83% of its 47°F output
Very good · beats 89%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 24,200 BTU/h at 5°F.
It will heat most of the year - its HSPF2 beats 96% 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.

Calculate my running cost

Details

Specifications24,000 BTU, R-454B

General
Brand	Mainline
Also sold as	Continental
Outdoor unit model	ML24HP230CALH-O
Series	ML Series
Type	Mini-split heat pump
Nominal size	24,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-454B
Connected (smart) capable	No
On the market since	May 20, 2024
Last certified	August 11, 2026
Cooling
SEER2Seasonal efficiency, higher is better	21.0 (range 21.0)
EER2Efficiency at 95°F outdoors	13.0
Cooling capacity	24,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	13.5
Capacity at 47°F	29,000 BTU/h
Capacity at 17°F	22,200 BTU/h
Capacity at 5°F	24,200 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	2.34
ENERGY STAR cold climate	Yes

Heating output as it gets colder83% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ML24HP230CALH-I 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.
ML24HP230CALH-I MAINLINE · cold climate	21.0	13.0	13.5	24,200	217607261
ML24HP230CALH-I MAINLINE · cold climate	21.0	13.0	13.5	24,200	215864348

Same unit, other model numbers1

These model numbers have exactly the same certified ratings and matchups as the Mainline ML24HP230CALH-O: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Continental CDHAS26BA-24-O

Yearly running cost in 10 large cities$536-$1,372

Phoenix, AZ$652/yr
Miami, FL$536/yr
Houston, TX$584/yr
Atlanta, GA$580/yr
Los Angeles, CA$562/yr
New York, NY$1,372/yr
Chicago, IL$1,111/yr
Denver, CO$922/yr
Seattle, WA$565/yr
Minneapolis, MN$1,140/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 Mainline ML24HP230CALH-O?: The Mainline ML24HP230CALH-O is rated at up to 21.0 SEER2 and 13.0 EER2 for cooling and up to 13.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
Is the Mainline ML24HP230CALH-O good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 24,200 BTU/h at 5°F with a COP of 2.34, so it is still 2.3 times as efficient as electric resistance heat at that temperature.
How much does the Mainline ML24HP230CALH-O cost to run per year?: At its rated efficiency it costs about $536-$1,372 a year in electricity in large U.S. cities, depending on climate and local rates - for example $652 in Phoenix and $1,140 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the Mainline ML24HP230CALH-O the same as the Continental CDHAS26BA-24-O?: 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 Mainline ML24HP230CALH-O?: ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses MAINLINE ML24HP230CALH-I.
What refrigerant does the Mainline ML24HP230CALH-O 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 $643/yrYou save $676/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 Mainline ML24HP230CALH-O

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: $643
Current system, per year: $1,319
You save per year: $676
Payback: 13.3 years
Net after 10 years: -$2,236

Cooling $402Heating $241Electricity used: 4,018 kWhSaved vs. a minimum-efficiency heat pump: $381

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 24,000 BTU models

DIRECT AIR DIRM4-24HXPRO28-1Z · cold climate21.0 SEER2 · 13.5 HSPF2
Midea MO1HS-H24B-2A · cold climate21.0 SEER2 · 13.5 HSPF2
Comfort-Aire A-VHP24SA-1 · cold climate21.0 SEER2 · 13.5 HSPF2
MRCOOL O-ES-24-HP-C-230C-O1 · cold climate21.0 SEER2 · 13.5 HSPF2
Capella CPPB-H24A-O · cold climate21.0 SEER2 · 13.5 HSPF2
Napoleon NDHAS26BA-24-O · cold climate21.0 SEER2 · 13.5 HSPF2
Bosch BMS500-AAS024-1CSXHD · cold climate21.0 SEER2 · 13.5 HSPF2
York YPAS24BLFASDQ1 · cold climate21.0 SEER2 · 12.2 HSPF2

See all 430 24,000 BTU mini-splits, ranked

Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of August 11, 2026. How we use the data.