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      3.5-ton central heat pump · Elite

      Mainline MLP15AY42AJ2N

      Below average cooling and heating efficiency for a 3.5-ton central heat pump, and certified for cold climates.

      Ranks #77 of 138 3.5 ton central heat pumps for cooling efficiency, and costs about $1,308 a year to run in a mixed climate like Atlanta.

      SEER2
      16.0 Cooling efficiency over a season
      Below average · beats 26%
      HSPF2
      8.1 Heating efficiency over a season
      Below average · beats 20%
      EER2
      11.7 Cooling efficiency on a 95°F day
      Average · beats 43%
      Heat at 5°F
      19,300 BTU/h47% of its 47°F output
      Average · beats 58%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 19,300 BTU/h at 5°F.
      • You want a choice of indoor units - 58 certified pairings.

      Think twice if…

      • Cooling cost matters most - its SEER2 is below average for central heat pumps.
      • You mainly need heat - its HSPF2 is below average for central heat pumps.

      Calculate my running cost

      Details

      Specifications3.5 ton, R-454B
      General
      BrandMainline
      Outdoor unit modelMLP15AY42AJ2N
      SeriesElite
      TypeCentral heat pump
      Nominal size3.5 ton
      CompressorVariable-speed units run longer at low powerTwo-stage
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceDecember 23, 2024
      Last certifiedApril 9, 2025
      Cooling
      SEER2Seasonal efficiency, higher is better16.0 (range 16.0)
      EER2Efficiency at 95°F outdoors11.7-12.0
      Cooling capacity40,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better8.1
      Capacity at 47°F40,000 BTU/h
      Capacity at 17°F27,000-40,000 BTU/h
      Capacity at 5°F18,400-19,300 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.00-2.10
      ENERGY STAR cold climateYes
      Heating output as it gets colder47% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with TCFY4821STANM at the standard test temperatures, in BTU/h:

      Certified matchups58 indoor units

      The same outdoor unit scores differently with each indoor unit and furnace. Ask your installer for the AHRI reference number of the exact system you are quoted.

      Indoor unitFurnaceSEER2EER2HSPF2Heat @5°FAHRI ref.
      TCFY4821STANM · cold climateML801V0754A17UH16.011.78.118,800216684851
      TCFY4824STANM · cold climateML962V1005A21M416.011.78.119,100216684858
      TCFY4824STANM · cold climateML801V0755A21UH16.011.78.118,900216684847
      TCFY4824STANM · cold climateML801V1005A21UHU16.011.78.118,800216684849
      TCFY4824STANM · cold climateML962V0855A21M416.011.78.119,200216684861
      TCFY4824STANM · cold climateML962V0705A21M416.011.78.119,100216684893
      TCFY4821STANM · cold climateML962V0855A21M416.011.78.119,200216684862
      TCFY4821STANM · cold climateML962V0705A21M416.011.78.119,100216684868
      TCFY4821STANM · cold climateML962V1005A21M416.011.78.119,100216684864
      MLH2VY4824STACN · cold climate-16.012.08.118,400216684909
      MLH2VY4821STACN · cold climate-16.012.08.118,500216684910
      TCFY4824STANM · cold climateML801V1505A24UH16.011.78.118,800216684839
      TCFY4821STANM · cold climateML802V1005A21DZ16.011.78.118,700216684840
      TCFY4824STANM · cold climateML802V1255A24DZ16.011.78.118,700216684843
      TCFY4824STANM · cold climateML801V1005A21DZ16.011.78.118,700216684841
      TCFY4821STANM · cold climateML801V1005A21UHS16.011.78.118,800216684838
      TCFY4824STANM · cold climateML801V1255A24UH16.011.78.118,800216684842
      TCFY4821STANM · cold climateML802V1004A17UH16.011.78.119,000216684844
      TCFY4821STANM · cold climateML801V1005A21UHU16.011.78.118,800216684846
      TCFY4821STANM · cold climateML801V1004A17UH16.011.78.119,000216684845
      TCFY4824STANM · cold climateML962V1155A24M416.011.78.118,800216684857
      TCFY4824STANM · cold climateML802V1505A24UH16.011.78.118,800216684850
      TCFY4824STANM · cold climateML802V1005A21DZ16.011.78.118,700216684848
      TCFY4824STANM · cold climateML951V1155A24M416.011.78.118,800216684804
      TCFY4824STANM · cold climateML921V0705A21M416.011.78.119,100216684805
      TCFY4824STANM · cold climateML921V1155A24M416.011.78.118,800216684802
      TCFY4824STANM · cold climateML921V0855A21M416.011.78.119,200216684806
      TCFY4824STANM · cold climateML951V1005A21UH16.011.78.119,000216684801
      TCFY4821STANM · cold climateML951V1005A21UH16.011.78.119,000216684803
      TCFY4821STANM · cold climateML921V1005A21M416.011.78.119,100216684800
      TCFY4821STANM · cold climateML921V0705A21M416.011.78.119,100216684807
      TCFY4821STANM · cold climateML921V0855A21M416.011.78.119,200216684808
      TCFY4824STANM · cold climateML921V1005A21M416.011.78.119,100216684810
      TCFY4821STANM · cold climateML951V0705A21M416.011.78.119,100216684815
      TCFY4821STANM · cold climateML951V1005A21M416.011.78.119,100216684814
      TCFY4824STANM · cold climateML951V0705A21M416.011.78.119,100216684813
      TCFY4824STANM · cold climateML951V1005A21M416.011.78.119,100216684812
      TCFY4821STANM · cold climateML801V0755A21UH16.011.78.118,900216684816
      TCFY4824STANM · cold climateML951V0855A21M416.011.78.119,200216684809
      TCFY4821STANM · cold climateML802V1005A21UH16.011.78.118,800216684822
      TCFY4821STANM · cold climateML951V0855A21M416.011.78.119,200216684811
      TCFY4824STANM · cold climateML802V1255A24UH16.011.78.118,800216684818
      TCFY4821STANM · cold climateML802V0754A17UH16.011.78.118,800216684821
      TCFY4824STANM · cold climateML801V1255A24DZ16.011.78.118,700216684820
      TCFY4821STANM · cold climateML801V0754A17DZ16.011.78.119,300216684819
      TCFY4821STANM · cold climateML801V1005A21DZ16.011.78.118,700216684828
      TCFY4824STANM · cold climateML801V0755A21DZ16.011.78.118,800216684825
      TCFY4821STANM · cold climateML802V0755A21DZ16.011.78.118,800216684823
      TCFY4821STANM · cold climateML801V1005A21UHN16.011.78.118,800216684830
      TCFY4821STANM · cold climateML801V0755A21DZ16.011.78.118,800216684829
      TCFY4821STANM · cold climateML802V0754A17DZ16.011.78.119,300216684827
      TCFY4824STANM · cold climateML802V0755A21UH16.011.78.118,900216684835
      TCFY4824STANM · cold climateML801V1005A21UHS16.011.78.118,800216684837
      TCFY4821STANM · cold climateML802V0755A21UH16.011.78.118,900216684831
      TCFY4824STANM · cold climateML802V1005A21UH16.011.78.118,800216684833
      TCFY4821STANM · cold climateML801V0704A17UH16.011.78.119,300216684832
      TCFY4824STANM · cold climateML801V1005A21UHN16.011.78.118,800216684834
      TCFY4824STANM · cold climateML802V0755A21DZ16.011.78.118,800216684836
      Yearly running cost in 10 large cities$1,175-$3,124

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

      Questions5
      What is the SEER2 rating of the Mainline MLP15AY42AJ2N?
      The Mainline MLP15AY42AJ2N is rated at up to 16.0 SEER2 and 11.7 EER2 for cooling and up to 8.1 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the Mainline MLP15AY42AJ2N good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 19,300 BTU/h at 5°F with a COP of 2.10, so it is still 2.1 times as efficient as electric resistance heat at that temperature.
      How much does the Mainline MLP15AY42AJ2N cost to run per year?
      At its rated efficiency it costs about $1,175-$3,124 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,446 in Phoenix and $2,608 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 Mainline MLP15AY42AJ2N?
      ENERGY STAR lists 58 certified combinations for this outdoor unit. The highest-rated ones use TCFY4821STANM, TCFY4824STANM, MLH2VY4824STACN.
      What refrigerant does the Mainline MLP15AY42AJ2N 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 $1,433/yrYou save $629/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 MLP15AY42AJ2N
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,433
      Current system, per year
      $2,063
      You save per year
      $629
      Payback
      23.8 years
      Net after 10 years
      -$8,706

      Cooling $880Heating $553Electricity used: 8,957 kWhSaved vs. a minimum-efficiency heat pump: $149

      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 3.5 ton models

      See all 138 3.5 ton central heat pumps, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of April 9, 2025. How we use the data.