Nest Learning Thermostat

Nest is a thermostat with Apple DNA developed by Tony Fadell. Potentially cut 20% to 30% of your US$1000 annual energy bill. Priced at $249, and get your money back in savings in one year. Looks good, too.

Update: via Ben Brooks. Marco Arment:

The problem arises when the Nest needs to charge itself and neither the heat nor air conditioning has turned on in a while, like on a mild day. Without a C circuit to take power from, it can only charge itself from running the system.

So it pulses the R-W heat circuit in short bursts to get power.

Brooks:

This isn’t likely something that will directly cause a problem, but it is putting unneeded wear and strain on your heating system — no way I would allow this.

If you have a boiler that reacts instantly, like the one Arment has, these short bursts can also be annoying. I would suggest Nest take a look at solar-powered Casio watches for Nest version two.

Update 2: Nest teardown. I think the LCD is a square; the cover glass makes it look circular.