They only go up to around 1200W, and those cost $200-300. From what I've seen, when using the immersion water-heater elements, you need at least a couple thousand watts to comfortably boil a batch - and immersion-type elements would inherently be more efficient because nearly all the heat they generate would be going into the liquid, whereas these band heaters would lose a lot to ambient unless seriously insulated. You'd probably need 2 or 3 of them, plus a whole bunch of insulation, resulting in a total cost that could get dangerously close to 4 figures, and probably not work any better than the common existing methods.
So, I don't think they'd be a good choice, especially for a boil kettle. If cost were no object, they might be sort of nice for maintaining mash temps, though the thermostat would likely need to be replaced with something more accurate...
Last edited by Funkenjaeger; 01-10-2008 at 02:22 PM.