On Feb 12, 1:13 pm, Paul M. Eldridge
wrote:

On 12 Feb 2007 08:18:13 -0800, "dpb" wrote:

....
they're switching thermostats, too, ...
....

Hmm, good point. Because it uses a triac, I had assumed (incorrectly)
that it works pretty much like a standard household dimmer.
....

The triac is essentially just a bi-directional gated switching circuit
able to be controlled for either voltage polarity, so unless there is
more internally than that, it is essentially just an enhanced switch.
Less expensive dimmers are essentially the same, more expensive may
include other circuitry to modify the waveform and phase to provide
nearer a sinusoidal voltage, but I'd guess these thermostats don't
have that sophistication.