On Fri, 19 Sep 2008 12:16:32 GMT, "JohnR66" wrote:

"John Grabowski" wrote in message
...

"Square Peg" wrote in message
...
Most coffee mug warmers are under-powered. One reviewer on Amazon said
that they were restricted to about 24 watts by law.

This one

http://www.amazon.com/Bunn-BCW-Warme...1796737&sr=8-3

is made for warming the whole coffee pot. It says it's 120V/15amp.
Several of the reviews say that they use it for a single cup, but it
keeps it too hot. It only has on/off -- no temperature control.

Can I put it on a 300 watt dimmer switch like this?

http://www.amazon.com/Lutron-Electro...1799800&sr=8-2

If not, is there a way to ramp the the power down as an external
thermostat?


You will probably be disappointed in the results and waste electricity at
the same time. The heating elements are designed to perform at a certain
voltage. As that decreases so will the heat level, but it will not be on
a straight line but rather a drastic curve due to the resistive nature of
the elements.

Take a look at what happens when a light bulb is dimmed. Not only is the
light output diminished, but the color of the light changes as well
because they were designed for certain voltage.
An incandescent light bulb is inefficient at producing light and it gets
much worse as the voltage is reduced, however, it is great at producing
heat.
If you reduce the voltage on a heating element, it will produce less heat
but is still nearly 100% efficient at producing the heat. It does not become
less efficient if that is what you were trying to say.

That would be my guess as well.

I'm not too worried about the efficiency curve or achieving 10 decimal
places of accuracy on the temperature. I'm mainly curious about (a) if
it will work at all and (b) it if will damage the unit.