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      18,000 BTU mini-split heat pump · Z-MAX

      ZERO ZMSB-18HVT-USHHCR2

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

      Ranks #129 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $448 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
      12.5 Cooling efficiency on a 95°F day
      Average · beats 44%
      Heat at 5°F
      17,800 BTU/h99% of its 47°F output
      Below average · beats 9%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 70% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 17,800 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

      Specifications18,000 BTU, R-454B
      General
      BrandZERO
      Outdoor unit modelZMSB-18HVT-USHHCR2
      SeriesZ-MAX
      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 sinceJune 1, 2026
      Last certifiedJuly 17, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better23.5 (range 23.5)
      EER2Efficiency at 95°F outdoors12.5
      Cooling capacity18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.0
      Capacity at 47°F18,000 BTU/h
      Capacity at 17°F15,500-18,000 BTU/h
      Capacity at 5°F17,800 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.80
      ENERGY STAR cold climateYes
      Heating output as it gets colder99% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with ZMSB-18HVT-USHHCR2 at the standard test temperatures, in BTU/h:

      Certified matchups2 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.
      ZMSB-18HVT-USHHCR2 · cold climate23.512.510.017,800216723130
      ZMSB-18HVT-USHHCR2 · cold climate23.512.510.017,800218665114
      Yearly running cost in 10 large cities$362-$1,104

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

      Questions5
      What is the SEER2 rating of the ZERO ZMSB-18HVT-USHHCR2?
      The ZERO ZMSB-18HVT-USHHCR2 is rated at up to 23.5 SEER2 and 12.5 EER2 for cooling and up to 10.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with.
      Is the ZERO ZMSB-18HVT-USHHCR2 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 17,800 BTU/h at 5°F with a COP of 1.80, so it is still 1.8 times as efficient as electric resistance heat at that temperature.
      How much does the ZERO ZMSB-18HVT-USHHCR2 cost to run per year?
      At its rated efficiency it costs about $362-$1,104 a year in electricity in large U.S. cities, depending on climate and local rates - for example $465 in Phoenix and $936 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 ZERO ZMSB-18HVT-USHHCR2?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated one uses ZMSB-18HVT-USHHCR2.
      What refrigerant does the ZERO ZMSB-18HVT-USHHCR2 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 $471/yrYou save $457/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 ZERO ZMSB-18HVT-USHHCR2
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $471
      Current system, per year
      $928
      You save per year
      $457
      Payback
      15.3 years
      Net after 10 years
      -$2,431

      Cooling $270Heating $202Electricity used: 2,945 kWhSaved vs. a minimum-efficiency heat pump: $241

      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 July 17, 2026. How we use the data.