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      3-ton central heat pump · DAVE LENNOX SIGNATURE XP21 SERIES

      Lennox XP21-036-230-

      Below average cooling and heating efficiency for a 3-ton central heat pump, but not rated for cold climates.

      Ranks #204 of 302 3 ton central heat pumps for cooling efficiency, and costs about $1,127 a year to run in a mixed climate like Atlanta.

      SEER2
      16.4 Cooling efficiency over a season
      Below average · beats 38%
      HSPF2
      8.0 Heating efficiency over a season
      Below average · beats 12%
      EER2
      12.5 Cooling efficiency on a 95°F day
      Very good · beats 80%
      Heat at 5°F
      - Not reported by the maker

      A good fit if…

      • You want a certified 3-ton central heat pump at a typical efficiency level.

      Think twice if…

      • You often see nights below 0°F - it is not cold-climate certified.
      • Cooling cost matters most - its SEER2 is below average for central heat pumps.
      • You mainly need heat - its HSPF2 is below average for central heat pumps.
      • You want the newest refrigerant - it uses R-410A, which is being phased down.

      Calculate my running cost

      Details

      Specifications3 ton, R-410A
      General
      BrandLennox
      Outdoor unit modelXP21-036-230-
      SeriesDAVE LENNOX SIGNATURE XP21 SERIES
      TypeCentral heat pump
      Nominal size3 ton
      CompressorVariable-speed units run longer at low powerTwo-stage
      RefrigerantR-410A
      Connected (smart) capableNo
      On the market sinceApril 2, 2018
      Last certifiedMarch 28, 2023
      Cooling
      SEER2Seasonal efficiency, higher is better16.4 (range 16.0-16.4)
      EER2Efficiency at 95°F outdoors12.2-12.5
      Cooling capacity34,800-35,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better8.0
      Capacity at 47°F34,000-34,200 BTU/h
      Capacity at 17°F23,200-23,400 BTU/h
      Capacity at 5°F-
      COP at 5°F2.0 = twice as efficient as a space heater-
      ENERGY STAR cold climateNo
      Heating output as it gets colder

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with CHX35-48B-**-*+TDR at the standard test temperatures, in BTU/h:

      Certified matchups2 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.
      CHX35-48B-**-*+TDREL280UH090E36B*16.412.58.0-202891593
      CH35-48B+TDR+TXVEL280UH070XE36A*16.012.28.0-203361971
      Yearly running cost in 10 large cities$1,003-$2,697

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

      Questions5
      What is the SEER2 rating of the Lennox XP21-036-230-?
      The Lennox XP21-036-230- is rated at up to 16.4 SEER2 and 12.5 EER2 for cooling and up to 8.0 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 2 certified matchups SEER2 ranges from 16.0-16.4.
      Is the Lennox XP21-036-230- good for cold climates?
      It is not cold-climate certified: none of its matchups meet the ENERGY STAR cold-climate criteria (a COP of at least 1.75 at 5°F among other limits). In places with frequent sub-zero nights, pick a cold-climate 3-ton model.
      How much does the Lennox XP21-036-230- cost to run per year?
      At its rated efficiency it costs about $1,003-$2,697 a year in electricity in large U.S. cities, depending on climate and local rates - for example $1,239 in Phoenix and $2,255 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 Lennox XP21-036-230-?
      ENERGY STAR lists 2 certified combinations for this outdoor unit. The highest-rated ones use CHX35-48B-**-*+TDR, CH35-48B+TDR+TXV.
      What refrigerant does the Lennox XP21-036-230- 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 $1,230/yrYou save $562/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 Lennox XP21-036-230-
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $1,230
      Current system, per year
      $1,792
      You save per year
      $562
      Payback
      23.1 years
      Net after 10 years
      -$7,384

      Cooling $751Heating $479Electricity used: 7,688 kWhSaved vs. a minimum-efficiency heat pump: $142

      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 March 28, 2023. How we use the data.