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      12,000 BTU mini-split heat pump · M series

      Lennox MPC012S4S-1L

      Very good cooling efficiency and average heating efficiency for a 12,000 BTU mini-split heat pump, but not rated for cold climates.

      Ranks #215 of 394 12,000 BTU mini-splits for cooling efficiency, and costs about $299 a year to run in a mixed climate like Atlanta.

      SEER2
      23.5 Cooling efficiency over a season
      Very good · beats 70%
      HSPF2
      10.0 Heating efficiency over a season
      Average · beats 43%
      EER2
      12.8 Cooling efficiency on a 95°F day
      Average · beats 56%
      Heat at 5°F
      6,800 BTU/h57% of its 47°F output
      Very good · beats 74%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 70% of mini-splits.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You often see nights below 0°F - it is not cold-climate certified.
      • You want the newest refrigerant - it uses R-410A, which is being phased down.

      Calculate my running cost

      Details

      Specifications12,000 BTU, R-410A
      General
      BrandLennox
      Outdoor unit modelMPC012S4S-1L
      SeriesM series
      TypeMini-split heat pump
      Nominal size12,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-410A
      Connected (smart) capableNo
      On the market sinceDecember 18, 2019
      Last certifiedMarch 4, 2025
      Cooling
      SEER2Seasonal efficiency, higher is better23.5 (range 22.4-23.5)
      EER2Efficiency at 95°F outdoors12.8-13.0
      Cooling capacity12,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better7.8-10.0
      Capacity at 47°F12,000 BTU/h
      Capacity at 17°F6,800-8,400 BTU/h
      Capacity at 5°F5,600-6,800 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.01-2.16
      ENERGY STAR cold climateNo
      Heating output as it gets colder57% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with MWMC012S4-*L at the standard test temperatures, in BTU/h:

      Certified matchups3 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.
      MWMC012S4-*L LENNOX23.512.810.06,800211034415
      MWMC012S4 LENNOX23.512.810.06,800210665602
      MWMB012S4-2L LENNOX22.413.07.85,600208546024
      Yearly running cost in 10 large cities$241-$736

      At each state's average electricity price and the city's typical heating and cooling hours.

      Questions5
      What is the SEER2 rating of the Lennox MPC012S4S-1L?
      The Lennox MPC012S4S-1L is rated at up to 23.5 SEER2 and 12.8 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 3 certified matchups SEER2 ranges from 22.4-23.5.
      Is the Lennox MPC012S4S-1L good for cold climates?
      It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 12,000 BTU model.
      How much does the Lennox MPC012S4S-1L cost to run per year?
      At its rated efficiency it costs about $241-$736 a year in electricity in large U.S. cities, depending on climate and local rates - for example $310 in Phoenix and $624 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Which indoor units work with the Lennox MPC012S4S-1L?
      ENERGY STAR lists 3 certified combinations for this outdoor unit. The highest-rated ones use LENNOX MWMC012S4-*L, LENNOX MWMC012S4, LENNOX MWMB012S4-2L.
      What refrigerant does the Lennox MPC012S4S-1L 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 $314/yrYou save $305/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 Lennox MPC012S4S-1L
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $314
      Current system, per year
      $619
      You save per year
      $305
      Payback
      14.8 years
      Net after 10 years
      -$1,454

      Cooling $180Heating $134Electricity used: 1,963 kWhSaved vs. a minimum-efficiency heat pump: $160

      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.

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      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of March 4, 2025. How we use the data.