Riku Mattila 
How to build a protection that prevents the non-frost-proof primary side of a heat exchanger from freezing?
Louis Botelho@rmattila74 Use electric heat tracing cables wrapped around the pipes and the heat exchanger. These cables provide a constant low level of heat to keep the fluid above freezing temperatures.
@Louisbotelho17 But how to make sure it's operational.
@rmattila74 Develop or use existing control systems that provide an easy-to-read status of all freeze protection mechanisms. Interfaces should allow for quick manual override if necessary.
@rmattila74 Implement a real-time monitoring system that can alert you via SMS or email if temperatures drop too low or if there's a system failure.