HVAC Rated
    Menu

      3.5-ton central heat pump · UHP Series

      MRCOOL UHP18048-O

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

      Ranks #28 of 138 3.5 ton central heat pumps for cooling efficiency, and costs about $1,341 a year to run in a mixed climate like Atlanta.

      SEER2
      17.5 Cooling efficiency over a season
      Average · beats 58%
      HSPF2
      9.5 Heating efficiency over a season
      Very good · beats 70%
      EER2
      12.0 Cooling efficiency on a 95°F day
      Average · beats 64%
      Heat at 5°F
      48,000 BTU/h100% of its 47°F output
      Below average · beats 39%

      A good fit if…

      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 48,000 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
      BrandMRCOOL
      Outdoor unit modelUHP18048-O
      SeriesUHP 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 sinceAugust 15, 2025
      Last certifiedMay 1, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better17.5 (range 15.2-17.5)
      EER2Efficiency at 95°F outdoors10.4-12.0
      Cooling capacity45,000-48,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better8.3-9.5
      Capacity at 47°F47,000-48,000 BTU/h
      Capacity at 17°F30,000-39,500 BTU/h
      Capacity at 5°F41,000-48,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.75-2.00
      ENERGY STAR cold climateYes
      Heating output as it gets colder100% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with UAH18048 - O at the standard test temperatures, in BTU/h:

      Certified matchups5 indoor units

      The same outdoor unit scores differently with each indoor unit and furnace. Ask your installer for the AHRI reference number of the exact system you are quoted.

      Indoor unitFurnaceSEER2EER2HSPF2Heat @5°FAHRI ref.
      UAH18048 - O · cold climate-17.512.09.548,000217730331
      **AECMPT60D2AA · cold climateMGM96EE100C5NB15.510.48.341,000218029383
      MCMP4860COTB · cold climateMGM96EE100C5NB15.510.48.341,000218029368
      **AECMPT60D2AA · cold climateMGM96EE080C4NB15.210.58.542,000218029382
      MCMP4860COTB · cold climateMGM96EE080C4NB15.210.58.542,000218029367
      Yearly running cost in 10 large cities$1,208-$3,199

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

      Questions5
      What is the SEER2 rating of the MRCOOL UHP18048-O?
      The MRCOOL UHP18048-O is rated at up to 17.5 SEER2 and 12.0 EER2 for cooling and up to 9.5 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 5 certified matchups SEER2 ranges from 15.2-17.5.
      Is the MRCOOL UHP18048-O good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 48,000 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 MRCOOL UHP18048-O cost to run per year?
      At its rated efficiency it costs about $1,208-$3,199 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,485 in Phoenix and $2,670 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 MRCOOL UHP18048-O?
      ENERGY STAR lists 5 certified combinations for this outdoor unit. The highest-rated ones use UAH18048 - O, **AECMPT60D2AA, MCMP4860COTB.
      What refrigerant does the MRCOOL UHP18048-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 $1,471/yrYou save $898/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 MRCOOL UHP18048-O
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,471
      Current system, per year
      $2,369
      You save per year
      $898
      Payback
      18.9 years
      Net after 10 years
      -$8,016

      Cooling $905Heating $566Electricity used: 9,194 kWhSaved vs. a minimum-efficiency heat pump: $353

      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 3.5 ton models

      See all 138 3.5 ton central heat pumps, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of May 1, 2026. How we use the data.