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      42,000 BTU mini-split heat pump · free matcht 24S R32

      TCL TMH42HDI2NAO0U25

      Very good cooling efficiency and average heating efficiency for a 42,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #7 of 61 42,000 BTU mini-splits for cooling efficiency, and costs about $1,039 a year to run in a mixed climate like Atlanta.

      SEER2
      24.0 Cooling efficiency over a season
      Very good · beats 75%
      HSPF2
      10.0 Heating efficiency over a season
      Average · beats 43%
      EER2
      11.2 Cooling efficiency on a 95°F day
      Below average · beats 11%
      Heat at 5°F
      31,000 BTU/h74% of its 47°F output
      Average · beats 48%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 75% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 31,000 BTU/h at 5°F.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • Nothing stands out - its ratings have no weak spot for its class.

      Calculate my running cost

      Details

      Specifications42,000 BTU, R-32
      General
      BrandTCL
      Outdoor unit modelTMH42HDI2NAO0U25
      Seriesfree matcht 24S R32
      TypeMini-split heat pump
      Nominal size42,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-32
      Connected (smart) capableNo
      On the market sinceDecember 16, 2025
      Last certifiedAugust 20, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better24.0 (range 20.0-24.0)
      EER2Efficiency at 95°F outdoors11.0-11.2
      Cooling capacity39,000-42,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.5-10.0
      Capacity at 47°F42,000 BTU/h
      Capacity at 17°F33,000-34,400 BTU/h
      Capacity at 5°F29,800-31,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.00
      ENERGY STAR cold climateYes
      Heating output as it gets colder74% kept at 5°F

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

      Certified matchups4 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.
      - · cold climate24.011.210.031,000218035810
      - · cold climate20.011.010.029,800218467786
      - · cold climate20.011.010.029,800218468377
      - · cold climate20.011.09.531,000218035806
      Yearly running cost in 10 large cities$828-$2,566

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

      Questions4
      What is the SEER2 rating of the TCL TMH42HDI2NAO0U25?
      The TCL TMH42HDI2NAO0U25 is rated at up to 24.0 SEER2 and 11.2 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 4 certified matchups SEER2 ranges from 20.0-24.0.
      Is the TCL TMH42HDI2NAO0U25 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 31,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
      How much does the TCL TMH42HDI2NAO0U25 cost to run per year?
      At its rated efficiency it costs about $828-$2,566 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,069 in Phoenix and $2,181 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      What refrigerant does the TCL TMH42HDI2NAO0U25 use?
      It uses 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 $1,086/yrYou save $1,079/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 TCL TMH42HDI2NAO0U25
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,086
      Current system, per year
      $2,166
      You save per year
      $1,079
      Payback
      14.8 years
      Net after 10 years
      -$5,208

      Cooling $616Heating $470Electricity used: 6,790 kWhSaved vs. a minimum-efficiency heat pump: $575

      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 42,000 BTU models

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      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of August 20, 2026. How we use the data.