Adding Heat Exchangers to Garage Solar Heater

I'm adding more heat exchangers to the solar heating system. This system captures the sun's energy in hot water, and sends it to the radiant floor in my garage/shop. However, the heat exchanger is the weak link. I'm going to upgrade it to capture more of the sun's energy. Playlist, garage build:    • Garage Workshop DIY Super Insulated Radian...   Video, re-using PEX fittings:    • Reusing Uponor Wirsbo Pex Expansion Fittings   PEX Expansion Tool: http://amzn.to/2E8AyAH “We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.”