I'm installing a multizone ductless minisplit in my house.

Many of the items I need have already been purchased, I have not purchased:

  • Line Sets
  • Nitrogen Testing Tank
  • 410a Refrigerant

I'm considering building my own line sets, it seems cheaper. But I cant seem to find the proper insulation for 1/4" & 3/8" lines. This look like the type of insulation I would want, but I cant find it for the sizes I need.


Would the 1/2" ID work for my 3/8" line? I think probably not. Can someone please provide me a resource where I can find the proper insulation?

In regard to the Refrigerant and Nitrogen... These seem a bit more expensive then I was hoping, think I can find someone in southern NH / northern MA that would rent something like this to a non-licensed person?


There will be more problems than a nitrogen tank. You also need a vacuum pump to pump the line set down once everything is assembled and a vacuum gauge, if the system pulls down and holds nitrogen is not needed but the non compressibles Need to be removed from the system. also depending on the length of the line set you will need additional r410 , I don't know any certified tech that would loan this equipment. Do you know there are HUGE fines for opening hvac/r equipment without a license, it has been many years but $20k rings a bell. You would not have any warranty, better to find a tech that will do it on the side for cash if you do have it set up correctly. Also depending on your local electrical code , permits for the branch circuit. The hvac license is not a state thing it is governed by the EPA you can get the equipment on line but need a license to buy Freon. For this reason I do not consider this a DIY job.

  • +1 for getting a tech to install so you have a warranty. – Lee Sam Jul 25 '18 at 19:56
  • I have a vacuum pump, a digital vacrometer and many of the other required tools. The installation guides asks for nitrogen tests and vacuum tests, not sure I want to only do one. From my understanding anyone can purchase AND handle R-410A, can you please be more specific about the fines you mention? Yes warranty would be nice, but unfortunately all the installers willing to come out to my house costs want more than $4k what it would cost me. I'm a pretty hardcore DIY'r I understand this isn't a job for the unmotivated. – Calvin Jul 25 '18 at 20:39
  • @calvin, this comment shows you need to be more motivated , check ,go online and get the core and level 1 license, this license is limited to 5lb systems, but if you think 100 psi nitrogen will be an accurate measure of 410a it is a total waste if the system will hold below 500um vacuum I have not heard that 410a no license is required, 134a is used for dusters, freeze spray and air horns. All dumped into the air but to use it in a hvac-r system a license is required. As I said there are massive fines for unlicensed opening of systems. Will check with vendor on 410. – Ed Beal Jul 25 '18 at 22:42

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