I remember having a discussion on an invention that was highly improbable given well known science. I actually got out a thermodynamics resource, and went through the calculations on the device, with the individual.
His response? "You've fallen into the trap of buying into the fallacy of newtonian physics!"
To be fair, though, there is a very small amount of science that supports descaling of calcium hardness in water by using very strong magnetic fields. Permanent magnets attached to the pipe won't do it. To really make it work, the magnetic field has to be incredibly strong. You can use variable magnetic fields induced by an electronic device to mimic the effect, with some success. The electrical coil devices sold by such as Home depot do this. They can have some positive effect. The joker to it all is that the effect is very small, and that it entirely depends on what is causing your hardness, the other characteristics of the water, and what your piping is. Hardness in many waters varies over time, and how much your pipes and faucets and such scale depends on your usage patterns. So, often the testimonials come from someone that may have had ideal water, or from someone that experienced a reduction due to seasonal variability of water quality, or a change in use or other variable.
The hardness molecules in water are divalent, and can be influenced by a strong magnetic field. My understanding of the result is that the molecules are essentially "aligned", and for a period of time, may clump together, and become less likely to "stick" to other substances. The problem is again that word "strong". It takes a lot of power to do this, through a pipe, with water flowing by. Most successful applications of this technology have been using very strong magnetic fields, or very small flows. When you try to extrapolate those results to home use, they don't produce real world effects at that home use scale.
The successful applications I have seen documented have been for industrial processes where replacing the pipes or cleaning them in place was difficult or cost prohibitive because of the resulting process shutdown. The cleaning was done by a company that brought in specialized equipment, and operated it on piping during the normal process operations for a finite amount of time to remove the existing scale. Most of the time, continuous operation of the devices wasn't the intent, just descaling of the pipes to restore them to original function. As someone stated at the beginning of the thread, sometimes it doesn't work, and you're out very expensive costs. But, sometimes it does.
I think in the homeowner realm, it very seldom will work. And, it definitely will not work on iron, only on calcium hardness.
