Originally Posted by JohnnyK81
I know you specifically didnt' ask me, but I'd go with copper. It's quick, it's easy (You don't have to braze, just solder. CLean them up, apply flux, heat with propane, apply solder, capillary action will take care of the rest). It transfers heat efficiently and quickly, and you can use type M for home use.
Check out this site on copper.
Table 3c is the all the pressures for copper.
Type M is the thinnest wall tubing.
Type L is the medium wall thickness
And Type K is the thickest wall and much harder to find.
From what I have read Type M should work just fine, I think I read the bursting pressure is around 300 psi.
You will only save $50 or so running an M system, so just go with L. M always has red lettering on it and L is always blue.
When you terminate the tube, use what is called drop ear 90's. They have ears on them with holes for securing to the walls.
From the Copper tube document it says brazed joints will handle 200 psi at 100 degree's. So in the heat of the summer 200. So I think we are good at 175 for quite a while until global warming heats us up.