Air Conditioners: One, Two and Variable Speed – Part 1 of 3

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One, Two and Variable Speed Air Conditioners – Part 1 of 3

Premium brands of Central A/C have various models.  Different models have different air conditioner compressor speed.  The speed a/c compressors operate at affects energy-efficiency, comfort and humidity-removal ability.

These are the 3 price-points for air conditioners, each with different air conditioner compressor speed:

  • expensive models have Variable-Speed
  • mid-priced have Two-Speed
  • lower priced have a One-Speed
  • Variable speed compressors run at many speeds to match their cooling output to current cooling demand.  Variable speed a/c has enhanced ability to adjust system cooling output by slowing down or speeding up the compressor as needed.  

Since Variable Speed a/c run at only the speed required, they run for longer periods of time.  This minimizes starts and stops that use more electricity.  Also, with most DFW homes’ ductwork in the attic, longer operating times further increase efficiency as they reduce the number of times the a/c must recool the ductwork.

  • Two-stage / speed compressors run at two speeds. The lower speed is 60-70% of the higher speed. Roughly 3/4 of the time, the system runs at the lower speed.  On hotter days, it switches to the higher speed.  Similar to variable-speed, Two-Stage a/c run for longer periods of time, minimizing starts & stops and more frequent need to recool the ductwork.

Longer cooling cycles translate to quieter operation, increased energy-efficiency, and enhanced humidity-control.  It takes 10 minutes for central a/c to reach its peak operating efficiency — while also have to recool the attic ductwork.  As compared to a single-stage a/c, a Two-Stage a/c remove more humidity by running at the lower speed. This is important feature in locations where humidity level are high, like DFW.

  • A single-stage / speed air conditioner has one compressor speed. The unit is either on off.


Al’s Plumbing, Heating & A/C offers American Standard as our premium brand.

american standard platinum gold silver series hvac

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