Competition: Nest Learning Thermostat: Teardown

Sparkfun published a nice article about Nest teardown.

I wonder if the battery is replaceable other than by "contacting technical support" (update: from the link below - no, it is not replaceable).

As usual, comments are as useful as the article if not more.

C Wire-less Setup

In particular, here's a link to an article describing a subtle problem: Undocumented Nest incompatibility with single-stage wiring. Incidentally, all three of three HVAC units I have do *not* have the C wire. Here's what Nest has to say:

• When Nest needs a common "C" wire
• Should my B wire go in Nest’s O/B connector or in the common (C) connector? (this one is actually very important because it is a thinly veiled liability disclaimer ("If a common wire is inserted into any connector other than C, it may blow a fuse in the HVAC system and damage Nest"). Be sure that your B wire is not actually a C wire. It would be nice if they provided a way to determine this for sure using something as simple as a multimeter, more on this later.
• Power Specifications for the Nest Learning Thermostat
• Does Nest need a common wire?
• What do Nest's wiring errors mean?

Would it be a regular dumb thermostat with nothing but dry contacts, I'd fiddle with wires. With this device, I guess I'd go for their installation service if there is anything out of ordinary. Or spend more time digging the actual wire layout. By the way, DIY installation video doesn't even hint at this problem, which makes me think there'll be lots of pissed off overconfident DIY dudes with attitude killing their Nest and blaming the manufacturer for that. Their Returns & Cancellations page is mum about what is gonna happen if the thermostat comes back dead because of customer's fault, it'll be interesting to see how this gets handled.

Afterthought: Multi-zone Setup

I missed the How does Nest work if I have multiple Nest Learning Thermostats in the same home? article when I was writing the original review. Stark contrast with DZ approach: one relatively expensive control panel per user (optional) and lots of dirt cheap sensors vs. many expensive control panels. The other side of the equation, though, is Apple aesthetics, learning capability and ability for everyone to control the temperature vs. powerful, though not quite below-average-IQ-friendly scheduler and unlimited tinkerability (at high price of your involvement, of course). These products are for totally different markets, that's for sure.