I need to insulate two outdoor minisplit lines. They are 3/8 and 1/4 inch copper lines - approximately 15 feet.

Edit: They came with insulation but after several years it is damaged and needs replacement. Perhaps my problem is that I didn't cover them with the plastic guides/shields. Though even if I did this I'd still have 3-6 feet exposed as the outdoor units are several feet from the wall.

I'm wondering what material I can use that is available to the home DIYer? I want it to be UV resistant and last a long time.

I've read recommendations on Armacell/Armaflex series of products. Armashield looks like it might be the best. But I'm having trouble figuring out which product to use? And where to buy it?

Armaflex Shield looks ideal - but I don't know where I can buy it. https://www.armacell.us/blog/post/best-pipe-insulation-choice-for-line-set-hvac-and-refrigeration-applications/

  • 2
    Are you sure you need to insulate them? My system came with insulated lines... And the contractors installed guides/shields/trim over them so they're never exposed to UV.
    – keshlam
    Commented Jul 14, 2023 at 4:22
  • The insulation got damaged by several years of weather and needs replacement. Perhaps the problem is that I didn't us the guides/shields... Commented Jul 15, 2023 at 2:47

3 Answers 3


EDPM rubber foam is fairly standard for refrigeration line insulation. Having an additional covering (metal or plastic) over that for more abuse resistance is also common.


Linesets for mini splits usually come with insulation on them, although the durability of the line set insulation varies. To be honest I'm kind of surprised you managed to find a 1/4 x 3/8 line set that WASN'T insulated.

As to where to buy them - HVAC supply houses should have line set insulation available to purchase.

Usually the way UV protection is handled is the line set is put inside of a line set cover, and the line set cover is supposed to protect the line set inside. As encerwal mentioned they also protect from abuse as well. Rectorseal is an example of a manufacturer that makes line set covers.


I'm going to try

  1. PVC tape to increase the diameter of the 1/4 inch pipe to 3/8.
  2. Armacell pipe insulation (for 3/8 inch pipe) - I will cut a slit and then use Armaflex 520 to seal it
  3. UV resistant tape to cover the Armacell pipe insulation

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