Lantley wrote:
Since hot water can freeze faster than cold I think you maybe going down the wrong road.
While the water in the pipes may freeze as long as the tank remains in motion the chances of it freezing are reduced.
The "hot water freezing faster" is the Mpemba effect, and it's rather uncertain whether or not it's true and under what conditions it may apply if it is true. This is in no small part because it's rather difficult to conduct a controlled experiment.
It is rather clear that hot water generally needs more heat energy removed to freeze than cold water, in as much as hot water must first become cold water before becoming ice. If you add heat to the water at the same rate as it's taken away by the environment while traveling, it won't freeze. This is no less sound than using a heated hose in winter time to keep the hose from freezing.
For what it's worth, my RV water heater does tend to blow out if left on at highway speeds (or perhaps just fail to light at highway speeds), requiring one to cycle the power to get it going again.
