HVAC Rated

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

Mainline ML36HP230LCM-O

Below average cooling efficiency and average heating efficiency for a 36,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #143 of 205 36,000 BTU mini-splits for cooling efficiency, and costs about $964 a year to run in a mixed climate like Atlanta.

SEER2
20.0 Cooling efficiency over a season
Below average · beats 18%
HSPF2
10.3 Heating efficiency over a season
Average · beats 55%
EER2
9.6 Cooling efficiency on a 95°F day
Below average · beats 4%
Heat at 5°F
26,600 BTU/h70% of its 47°F output
Very good · beats 78%

A good fit if…

  • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 26,600 BTU/h at 5°F.
  • 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

Specifications36,000 BTU, R-454B
General
BrandMainline
Also sold asCooper&Hunter, ApooDr, AproDr
Outdoor unit modelML36HP230LCM-O
SeriesML Series
TypeMini-split heat pump
Nominal size36,000 BTU
CompressorVariable-speed units run longer at low powerContinuously variable
RefrigerantR-454B
Connected (smart) capableNo
On the market sinceMay 20, 2024
Last certifiedAugust 11, 2026
Cooling
SEER2Seasonal efficiency, higher is better20.0 (range 20.0)
EER2Efficiency at 95°F outdoors9.6
Cooling capacity36,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better10.3
Capacity at 47°F38,000 BTU/h
Capacity at 17°F26,800 BTU/h
Capacity at 5°F26,600 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater2.20
ENERGY STAR cold climateYes
Heating output as it gets colder70% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ML36HP230STDCAS-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 unitSEER2EER2HSPF2Heat @5°FAHRI ref.
ML36HP230STDCAS-I MAINLINE · cold climate20.09.610.326,600217607303
ML36HP230STDCAS-I MAINLINE · cold climate20.09.610.326,600215864390
Same unit, other model numbers2

These model numbers have exactly the same certified ratings and matchups as the Mainline ML36HP230LCM-O: the same equipment under another brand, or a variant code for voltage, colour or market. Everything on this page applies to them.

Yearly running cost in 10 large cities$847-$2,317

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 ML36HP230LCM-O?
The Mainline ML36HP230LCM-O is rated at up to 20.0 SEER2 and 9.6 EER2 for cooling and up to 10.3 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
Is the Mainline ML36HP230LCM-O good for cold climates?
Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 26,600 BTU/h at 5°F with a COP of 2.20, so it is still 2.2 times as efficient as electric resistance heat at that temperature.
How much does the Mainline ML36HP230LCM-O cost to run per year?
At its rated efficiency it costs about $847-$2,317 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,051 in Phoenix and $1,942 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
Is the Mainline ML36HP230LCM-O the same as the Cooper&Hunter CH-R36LCU-230VO?
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 Mainline ML36HP230LCM-O?
ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses MAINLINE ML36HP230STDCAS-I.
What refrigerant does the Mainline ML36HP230LCM-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 $1,047/yrYou save $842/yrSee details ↓
1. Where you live
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.

2. The heat pump Mainline ML36HP230LCM-O
3. What it replaces
4. Price replace the example with your quote
Heat pump, per year
$1,047
Current system, per year
$1,889
You save per year
$842
Payback
16.0 years
Net after 10 years
-$5,078

Cooling $634Heating $413Electricity used: 6,543 kWhSaved vs. a minimum-efficiency heat pump: $407

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

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