Selecting a Line Set for Your Mini-Split AC System


One or more line sets is needed to install any mini-split air conditioning system. This is the component used to connect an indoor unit to an outdoor unit, as explained in our video on how line sets work. We offer pre-flared, insulated line-sets, which make for easier installation.

When selecting a refrigerant line-set for a ductless mini-split system, you need to consider three sizes: the liquid-line diameter, the suction-line diameter, and the length.

  • Liquid lines bring refrigerant back to the outdoor compressor.
  • Suction lines supply refrigerant to the indoor unit, while preventing overheating at the compressor.

The necessary diameters of the liquid and suction lines depend on the requirements of the indoor mini-split unit. The length of your line-set should be based on the distance between the indoor and outdoor units, but make sure to look at the distance limitations of each mini-split system.  All systems have maximum distance and height differences between the units, as well as a maximum refrigerant pre-charge. A typical mini-split system comes pre-charged with sufficient R-410A refrigerant for a 25-foot run. Most systems are rated for runs up to 50 feet if necessary to connect to an outdoor unit that is further away, however line sets longer than 25 feet require additional refrigerant.

For more information on selecting line sets and how they work, check out our video:

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2 Responses to Selecting a Line Set for Your Mini-Split AC System

  1. thanks for the article..tremendous review.great worked! now i deeply understand about air conditioner.i try to figure out lately until i find your blog.god bless u..i will bookmark your site

  2. I like your post,very informative

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