Originally Posted by
ballvalve
Sounds like you have not done too many radiant installs. Installers do not bother to use 20$ a foot product between zones because the heat loss still heats the house, and that loss is not a calculation of interest. If it is, simple pipe insulation suffices.
Poly drain line with pex foamed into the center logically seems like something for exterior use between buildings, snowmelt supply lines, or for the brain dead ultra rich that have contractors that get a 20% upcharge on silly products they spec and install.
If you used 25 feet of this from water heater to your first hot water fixture, the entire lifetime of the house heat loss savings would not recover its cost.
PEX - .33 cents a foot + standard insulation = .59 cents a foot.
Or this junk at 17 to 25$ a foot that cannot go through a joist or 2x4 wall.
I think your use specification is faulty.