In my situation, it would be *linesets* of the refrigerant pipes for ductless splitless units.
Installer used the good stuff...rolls of tubing with insulation already on it. My electrician told me alot of HVAC guys use regular copper, then slowly put the Armourcell on it, etc.

Long story short, there is some areas in which insulation is not up to par...
What is the primary reasoning's for insulation, just short of keeping the refrigerant as cool as possible (no cool/heat loss) and condensation ?

The areas in my install in which insulation is short or need *better work*
- the last 8 inches or so where the linesets go into the condensers. I would have expected insulation all the way up to to the last 4 inches or so where they make the flared connection.

- I have quite some vertical runs. Where they brazed the linesets to the linesets coming to the air handler, they cut back around 12" of insulation to make the brazed connection. Only 1 or 2 of these dual linesets I have issues with. On the others, where I pointed it out, he wrapped the exposed copper with armorcell. In the 2 areas in which another worker was doing it, I pointed it out and he just wrapped it in 1 layer with the *foam insulating tape*, that was like 4 inches wide similar to a mastic tape roll but it was the foamy stuff but the overall thickness is thin