I've currently got several Cadet RM162 Registers (in-wall heaters) in my home. They're powered with 220VAC power. I'm curious about the challenges of converting some to the sort of electric radiator that appears common in Europe. From what I can tell, the voltage is the same, and the load (current) is similar. But what is unclear is if 60Hz power in the US will be a problem for heaters designed to run on 50Hz power more common in EU/UK.
One retail site I've found many of these on is Geyser.
Since the resistive heating element really won't care about the frequency of the AC power, the real question is about how the built-in thermostat will handle it.