Edit 2014-11: Nevermind.
Another idea I don’t want to bother thinking about patenting-
How about an intelligent heating tape/sleeve that can be used to keep something (for example, water pipes) permanently above some pre-set temperature?
I imagine a sleeve (possibly surrounded by insulation) that can be put around a water pipe, that contains:
- A resistive heater
- A temperature sensor
- A FET to turn the heater on when the temp falls below the set value (a thermostat)
This would be great to prevent pipes from freezing in the winter in unused rooms (with minimum expenditure of energy). Of course, one can imagine lots of other uses.
I’d power the thing from 12v or so, so nobody gets electrocuted if they cut into it, and to simplify conformance with building codes. You’d probably want the power supply to have a battery backup so it’ll keep working if the power goes out for a while.
If it’s used on a copper pipe, the pipe itself could form the return path, leaving only a single wire to power the thing.
It would have to be segmented so that the stuff can be cut or torn to the desired length. Each segment should have its own thermostat so only the part that needs heat consumes power. And it should be removable without too much trouble, to allow for repair access to the pipe.
Does this thing already exist? Anybody know? (Bill, you reading this?)
It doesn’t quite exist. There’s AC powered heating cables – and of course you can’t cut them. You can see one at http://tinyurl.com/yc7feer. I spent hours underneath my NH house installing this stuff (and let me tell you, being under that house is no fun at all), and we’ve never used it.
Maybe that’s it. We don’t really know what’s in the little orange box – maybe it drops the voltage (tho I doubt it).
I was thinking you’d want each segment to have its own thermostat (sensor) so it can heat independent of the rest of the sleeve. That way the spots that need more heat (the less insulated ones) can get it without wasting power on the rest.
The orange box has a black thing on it that needs to be placed against the pipe. It’s a temperature sensor. It turns the current on and off as needed. The cord is available in different lengths so you can set up different “zones” if you want.
The installation instructions are to tape the cord to the pipe, then wrap it all in fiberglass insulation.