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      18,000 BTU mini-split heat pump · 3PAMS

      PerfectAire 3PAMSHH18-SZO-20.5

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

      Ranks #207 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $442 a year to run in a mixed climate like Atlanta.

      SEER2
      22.0 Cooling efficiency over a season
      Average · beats 48%
      HSPF2
      10.6 Heating efficiency over a season
      Average · beats 65%
      EER2
      13.0 Cooling efficiency on a 95°F day
      Average · beats 62%
      Heat at 5°F
      17,200 BTU/h96% of its 47°F output
      Below average · beats 27%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 17,200 BTU/h at 5°F.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • You want the newest refrigerant - it uses R-410A, which is being phased down.

      Calculate my running cost

      Details

      Specifications18,000 BTU, R-410A
      General
      BrandPerfectAire
      Outdoor unit model3PAMSHH18-SZO-20.5
      Series3PAMS
      TypeMini-split heat pump
      Nominal size18,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-410A
      Connected (smart) capableNo
      On the market sinceJune 3, 2020
      Last certifiedJune 13, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better22.0 (range 19.4-22.0)
      EER2Efficiency at 95°F outdoors12.5-13.0
      Cooling capacity17,000-18,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.0-10.6
      Capacity at 47°F18,000 BTU/h
      Capacity at 17°F10,900-11,100 BTU/h
      Capacity at 5°F16,400-17,200 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.89-1.90
      ENERGY STAR cold climateYes
      Heating output as it gets colder96% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with 3PAMSHH18-UVW 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.
      3PAMSHH18-UVW PERFECTAIRE · cold climate22.013.010.617,200214389985
      2PAMSHH18-SZW-20 PERFECTAIRE19.412.510.016,400207338159
      Yearly running cost in 10 large cities$385-$1,064

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

      Questions5
      What is the SEER2 rating of the PerfectAire 3PAMSHH18-SZO-20.5?
      The PerfectAire 3PAMSHH18-SZO-20.5 is rated at up to 22.0 SEER2 and 13.0 EER2 for cooling and up to 10.6 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 2 certified matchups SEER2 ranges from 19.4-22.0.
      Is the PerfectAire 3PAMSHH18-SZO-20.5 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 17,200 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 PerfectAire 3PAMSHH18-SZO-20.5 cost to run per year?
      At its rated efficiency it costs about $385-$1,064 a year in electricity in large U.S. cities, depending on climate and local rates - for example $479 in Phoenix and $893 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 PerfectAire 3PAMSHH18-SZO-20.5?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated ones use PERFECTAIRE 3PAMSHH18-UVW, PERFECTAIRE 2PAMSHH18-SZW-20.
      What refrigerant does the PerfectAire 3PAMSHH18-SZO-20.5 use?
      It uses R-410A. R-410A is being phased down under the EPA AIM Act, and new systems are moving to R-454B and 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 $478/yrYou save $450/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 PerfectAire 3PAMSHH18-SZO-20.5
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $478
      Current system, per year
      $928
      You save per year
      $450
      Payback
      15.6 years
      Net after 10 years
      -$2,501

      Cooling $288Heating $190Electricity used: 2,989 kWhSaved vs. a minimum-efficiency heat pump: $234

      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 June 13, 2026. How we use the data.