What is the reason that Raypack will void your warranty for a heat exchanger if your water has FC levels more than 3ppm but the Pool School recommends much higher levels? What am I missing? Will the higher chlorine levels damage my heat exchanger?
They are assuming 3 FC with no CYA. That's actually lower than the EPA limit for drinking water, which is 4. So I;d like to see them deny a warranty based on that! Anyway, the technical part of the CYA/FC is here. The relevent graph
Okay, so it appears that higher chlorine may be recommended for better sanitizing but will it dissolve the copper in the heat exchanger? In my case, my CYA is around 65 and FC between 6-7 (although I initially shot to 12 but let it burn off by itself). PH never below 7.2 and generally stays around 7.8 to 8.0 with ALK at 100. Heater is brand new but exchanger developed a leak in 2 months.