Ionic compounds like copper oxide and calcium carbonate provide protection from copper oxidation.
The trick for calcium carbonate is to provide a very thin film without triggering a full runaway scaling event.
The problem is that any calcium carbonate layer provides a substrate that new calcium carbonate can attach to and grow very fast under scaling conditions.
The water in a heater has a higher CSI due to the higher water temperature in the heater when it is firing.
As copper ages, it develops a protective patina of copper oxide, which is the brown compared to the elemental copper you can see where the copper was sanded to remove the copper oxide for soldering.
The copper in copper oxide is already oxidized, so it is not susceptible to further oxidation.
Low pH will dissolve copper oxide and expose the elemental copper to oxidation.
The trick for calcium carbonate is to provide a very thin film without triggering a full runaway scaling event.
The problem is that any calcium carbonate layer provides a substrate that new calcium carbonate can attach to and grow very fast under scaling conditions.
The water in a heater has a higher CSI due to the higher water temperature in the heater when it is firing.
As copper ages, it develops a protective patina of copper oxide, which is the brown compared to the elemental copper you can see where the copper was sanded to remove the copper oxide for soldering.
The copper in copper oxide is already oxidized, so it is not susceptible to further oxidation.
Low pH will dissolve copper oxide and expose the elemental copper to oxidation.
