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      18,000 BTU mini-split heat pump · LEA Series

      NOVAIR LEA18SZ26-O

      Very good cooling efficiency and excellent heating efficiency for a 18,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #67 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $360 a year to run in a mixed climate like Atlanta.

      SEER2
      24.0 Cooling efficiency over a season
      Very good · beats 75%
      HSPF2
      13.5 Heating efficiency over a season
      Excellent · beats 96%
      EER2
      13.5 Cooling efficiency on a 95°F day
      Very good · beats 74%
      Heat at 5°F
      14,000 BTU/h72% of its 47°F output
      Excellent · beats 90%

      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 14,000 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 96% of mini-splits.
      • 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

      Specifications18,000 BTU, R-454B
      General
      BrandNOVAIR
      Outdoor unit modelLEA18SZ26-O
      SeriesLEA Series
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceJuly 18, 2025
      Last certifiedMay 28, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better24.0 (range 20.0-24.0)
      EER2Efficiency at 95°F outdoors12.5-13.5
      Cooling capacity16,000-18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.5-13.5
      Capacity at 47°F17,000-20,000 BTU/h
      Capacity at 17°F13,900-15,000 BTU/h
      Capacity at 5°F12,800-14,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater2.10-2.35
      ENERGY STAR cold climateYes
      Heating output as it gets colder72% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with 3LEA18USK-I at the standard test temperatures, in BTU/h:

      Certified matchups5 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.
      3LEA18USK-I · cold climate24.013.511.113,000217606292
      LEA16CONSK-I · cold climate23.812.513.513,100217606318
      4LEA18USK-I · cold climate23.512.710.812,800217606296
      LEA18CASS-I · cold climate20.712.511.412,800217606311
      LEA18DUCT-I · cold climate20.012.510.514,000217606315
      Yearly running cost in 10 large cities$332-$851

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

      Questions5
      What is the SEER2 rating of the NOVAIR LEA18SZ26-O?
      The NOVAIR LEA18SZ26-O is rated at up to 24.0 SEER2 and 13.5 EER2 for cooling and up to 13.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 5 certified matchups SEER2 ranges from 20.0-24.0.
      Is the NOVAIR LEA18SZ26-O good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 14,000 BTU/h at 5°F with a COP of 2.35, so it is still 2.4 times as efficient as electric resistance heat at that temperature.
      How much does the NOVAIR LEA18SZ26-O cost to run per year?
      At its rated efficiency it costs about $332-$851 a year in electricity in large U.S. cities, depending on climate and local rates - for example $404 in Phoenix and $707 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 NOVAIR LEA18SZ26-O?
      ENERGY STAR lists 5 certified combinations for this outdoor unit. The highest-rated ones use 3LEA18USK-I, LEA16CONSK-I, 4LEA18USK-I.
      What refrigerant does the NOVAIR LEA18SZ26-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 $399/yrYou save $494/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 NOVAIR LEA18SZ26-O
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $399
      Current system, per year
      $893
      You save per year
      $494
      Payback
      13.2 years
      Net after 10 years
      -$1,557

      Cooling $249Heating $149Electricity used: 2,492 kWhSaved vs. a minimum-efficiency heat pump: $289

      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 18,000 BTU models

      See all 465 18,000 BTU mini-splits, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of May 28, 2026. How we use the data.