There are multiple factors which can contribute to corrosion within a closed loop system. For this blog we will concentrate on erosion corrosion. This is caused by particulate in the system sand blasting the piping, causing leaks typically in elbows and threaded sections of the piping. This can also be damaging to small areas of newer high efficiency boilers. There are many factors that can lead to this particulate, including improper cleaning of a hydronic system after installation, improper chemistry used in the system, or a complete lack of chemistry. Routine checks of system iron and copper (both dissolved and total) should be performed to monitor against this. The American Boiler Manufacturer Association sets limits of less than one ppm of iron and less than 1/2 ppm of copper. If a higher level of these metals is found within the system from routine testing, your water treatment partner may recommend flushing the system to remove the debris or installing a filter to clean up the undissolved iron/copper and protect the rest of the system.