It's not electric, it's Thermo-mechanical. It has a mechanical device in it that triggers the air to close once the temperature rises; it's a metal wound spring that concracts/relaxes with temperature changes, the pushes a small trip/trigger that engages a preset primary air selection. It's a pretty cool idea, there are a few threads here somewhere with pictures of the mechanism.Thanks for the explanation. I actually printed out the entire EPA list and whittled it down to the England brand and a couple of others, but they were more difficult to obtain. But no where has it explained the smart feature, if it is electronic, I think I'll stick to old fashion! lol