Connecting a copper pipe directly to an aluminum tank submerged in water creates an electrochemical cell, where the water acts as the electrolyte and the metals serve as electrodes. If the copper and aluminum are electrically connected, rapid galvanic corrosion will occur due to the short circuit across the cell. Separation of the metals by a non-conductive barrier such as a long plastic pipe or using very pure water can significantly reduce corrosion rates. The voltage driving this corrosion can be calculated using standard electrode potentials. Using polymer laminate pipes is recommended to prevent galvanic corrosion in potable water systems.
Plumbing engineers, corrosion specialists, HVAC technicians, and anyone involved in designing or maintaining water heating systems with mixed-metal components.
Now there is something I hadn't thought of. It would be cool if I could harvest the electricity. I doubt it would be worth disolving the plumbing in my heater.Baluncore said:Welcome to PF.
The different metals are the plates of an electrochemical cell.
The water is the electrolyte.
If the metals are connected, there will be rapid corrosion, as the connection represents a short circuit across the cell. If you can separate the metals with a long length of plastic pipe, or the water was very pure, then the cell may not discharge, and the metals will only dissolve in the water slowly.
You can work out the voltage of the cell using electrode potentials.
https://en.wikipedia.org/wiki/Standard_electrode_potential_(data_page)