Two 1" Lines of Pex-Al-Pex wrapped in closed cell Reflective insulation and fed inside 4" flexible non-perforated drain tile.  Standard Lengths are 200', 250' and 300' rolls. 

Requires 1" Pex-Al-Pex Compression fittings.  See Photo Below.
 1" Pex-Al-Pex shown on left, Standard 1" Pex on right.