[jeff5may]

The newer minisplit units are using long parallel runs of small diameter, thin wall, ribbed tubes in their heat exchangers. The superconducting supercomputers have led them in this direction. Apparently, some pressure drop is a good thing. More surface area is always better, as is turbulent flow.

There are charts and formulas all over the web (and this site) that can help you predict how your design will act before you actually install it. I used coolpack and the SWEP literature a lot to make things jive. The literature ac_hacker cited is also awesome.

For a 4 ton rig, you will need to do your homework to ensure the rig will be reliable. For this half ton build, it will probably work well without lots of modeling. However, it will be good practice to get your hands dirty and for measuring performance. I perfected my brazing skills on small systems and built up my tool set.