Why do hydronic towel warmers need to be on a closed loop system?

We have discontinued our Hydronic towel dryers, but here is some more information for those who currently have them installed. 

 

Hydronic towel warmers are not designed to work with domestic hot water systems. They need to be connected to a closed water system (hydronic) with a corrosion inhibitor and with its own heat source (as outlined in the instruction manual). See diagram attached as an example. If the towel warmer is heated directly from the domestic hot water system, the heat output will likely be limited, and the constant flow of fresh water throughout it will corrode the unit over time.

Please view the attached diagrams Hydronic Diagrams