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      3.5-ton central heat pump · AU Series

      AI AIR CONDITIONING AUO19-42N2-M3H-S

      Average cooling efficiency and very good heating efficiency for a 3.5-ton central heat pump, and certified for cold climates.

      Ranks #40 of 138 3.5 ton central heat pumps for cooling efficiency, and costs about $1,365 a year to run in a mixed climate like Atlanta.

      SEER2
      16.7 Cooling efficiency over a season
      Average · beats 43%
      HSPF2
      9.5 Heating efficiency over a season
      Very good · beats 70%
      EER2
      11.7 Cooling efficiency on a 95°F day
      Average · beats 43%
      Heat at 5°F
      46,000 BTU/h92% of its 47°F output
      Below average · beats 20%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 46,000 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 70% of central heat pumps.
      • 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

      Specifications3.5 ton, R-454B
      General
      BrandAI AIR CONDITIONING
      Also sold asMitsutomo, Multi MFG, ECO-AIR
      Outdoor unit modelAUO19-42N2-M3H-S
      SeriesAU Series
      TypeCentral heat pump
      Nominal size3.5 ton
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceOctober 10, 2024
      Last certifiedSeptember 16, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better16.7 (range 16.7)
      EER2Efficiency at 95°F outdoors11.7
      Cooling capacity42,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.5
      Capacity at 47°F50,000 BTU/h
      Capacity at 17°F39,500 BTU/h
      Capacity at 5°F46,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.90
      ENERGY STAR cold climateYes
      Heating output as it gets colder92% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with AUH2-48N2-DM3E at the standard test temperatures, in BTU/h:

      Certified matchups1 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.
      AUH2-48N2-DM3E · cold climate16.711.79.546,000215866709
      Same unit, other model numbers3

      These model numbers have exactly the same certified ratings and matchups as the AI AIR CONDITIONING AUO19-42N2-M3H-S: 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$1,184-$3,293

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

      Questions6
      What is the SEER2 rating of the AI AIR CONDITIONING AUO19-42N2-M3H-S?
      The AI AIR CONDITIONING AUO19-42N2-M3H-S is rated at up to 16.7 SEER2 and 11.7 EER2 for cooling and up to 9.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the AI AIR CONDITIONING AUO19-42N2-M3H-S good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 46,000 BTU/h at 5°F with a COP of 1.90, so it is still 1.9 times as efficient as electric resistance heat at that temperature.
      How much does the AI AIR CONDITIONING AUO19-42N2-M3H-S cost to run per year?
      At its rated efficiency it costs about $1,184-$3,293 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,477 in Phoenix and $2,765 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Is the AI AIR CONDITIONING AUO19-42N2-M3H-S the same as the Mitsutomo UHO42-NB-LD-Q?
      Yes, as far as the certified ratings go. ENERGY STAR lists 4 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 AI AIR CONDITIONING AUO19-42N2-M3H-S?
      ENERGY STAR lists 1 certified combination for this outdoor unit. The highest-rated one uses AUH2-48N2-DM3E.
      What refrigerant does the AI AIR CONDITIONING AUO19-42N2-M3H-S 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 $1,475/yrYou save $822/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 AI AIR CONDITIONING AUO19-42N2-M3H-S
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,475
      Current system, per year
      $2,297
      You save per year
      $822
      Payback
      19.5 years
      Net after 10 years
      -$7,782

      Cooling $885Heating $589Electricity used: 9,217 kWhSaved vs. a minimum-efficiency heat pump: $306

      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 September 16, 2026. How we use the data.