I have spent some time researching radiant floor systems, and would like some input about the open system that is promoted by Radiantec and other companies that cater to the DIY. Every professional HVAC that I read the opinions of say they will never use such a system because the potable water will stagnate all summer, making it unsafe. While I may respect their professional status, they never address the design which insures that the potable water always flows through the floor tubing prior to arriving at the faucet, so the system is designed to prevent stagnation. Does anyone have an opinion on the subject? Is there really any validity to the stagnation argument, or is it just “tradition”? If you are agains’t such a system, please explain why.