You know that those sacrificial anodes are simply zinc, right? One of the most plentiful metals on the planet?

Why would anyone on earth not make those simply swappable, like on boat motors, and on ocean going vessels.

We have been building ocean going vessels out of metal for over a century now. I think those so-called engineering challenges are solved.

Ever notice that the vast majority of oxidation actually occurs ABOVE the waterline?

Care to guess why?

Here's a hint, look at the first 3 letters of the word "oxidation."

Edit to add: Plus there's different metal choices for the actual heat exchangers, such as stainless 2507 or even titanium, which is extremely resistant to such corrosion, and for the parts of the building that do not need heat exchange, an insulating coating will mitigate nearly all oxidation issues.