I figure. I've never had to use one at full capacity ever even in really freezing situations. But you do need to keep a close watch on humidity because they dry out the air. I did run across a new simple one lately . It doesn't have a lot of digital crap. It does come close to the quality of the original delonghi oil filled heaters for around $29. And this one didn't cost much more so the simple ones are still out there. Who would use an electronic device at full blast for hours on end anyway? That's just asking for trouble.I don't know the answer to that question. I only use one mini radiant heater and it is 700 watts max. I would guess that the settings for the two switch models aren't the same across all brands. A quick google search pulled up a few that are 600 watts on one switch and 900 watts on the other. So I suppose Low would be one switch on and 600 watts, medium would be the other switch on and 900 watts, high would be both switches on and 1500 watts.