[dankoss]

I have a "wireless" thermostat (Honeywell Redlink) and there are a lot of problems you have to think through to make it work. In particular, what is the failure mode when the thermostat can't communicate with the furnace? What if your internet goes down and it can't communicate with your phone? You might need a different failsafe for when it's 0C vs 25C outside, but what if your exterior temp sensor stops working or can't communicate with the furnace? Not to mention the security implications of having an appliance on your network.

All these problems are made much simpler with a wired thermostat and battery backup. I wish it was easier, but in this case "smart" doesn't really buy you much energy or UX savings over a simple programmable wired device.

[icebraining]

If the Internet goes down, you could still connect locally. It could even create its own wifi hotspot, like many devices nowadays.

Not to mention the security implications of having an appliance on your network.

Yeah, but the Nest is already connected.