All thermostats use power continuously. It is supplied from the furnace/AC. It's 24v AC, I believe. Most of the programmable thermostats also come with a backup battery so that the program isn't lost every time the power is interrupted. That's the only reason it needs to have a battery.
That's not true. Most thermostats only draw their power from internal alkaline batteries. I know this because I had to run a common line from my furnace to my nest thermostat in order to energize it. My gas furnace runs on a 24v system.
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What use is this? I have Satchwell thermostats on my walls that switch the full mains current to my heaters.
This Nest thing apparently cannot replace those. It only switches low voltage.
Currently Nest only supports 24v systems. In the future they will probably release another line of 120v and 240v systems. Looking forward to one with the ability to hook up a Humidifier.
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Apparently. I'd expect any furnace system installed in the last 30 years to have a digital thermostat, if a simple one, and since furnace systems don't last much longer than 30 years that the old mechanical types would be far more scarce. I've actually got one of those on the wall in my house but it's no longer in service. Anyhow the bottom line is, installing a Nest to replace another digital thermostat should not require running another line to the furnace. Isn't that right?
It depends on the type of furnace. If the furnace has a logic board (mid to high efficiency) then no, you don't need to run a line. In my case I have a conventional (low efficiency) and need to run a common line.
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This is what my fancy building (constructed in 2003) has for a thermostat. It looks like it is from the 1970s!
I can't see any way that I can use a smart thermostat in my place, and I've been eyeing Nest and others for a while. Le sigh...
Why can't you run a smart thermostat like the nest in your place? I replaced my thermostat from the 1950's with a nest.
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Presumably Apple is aiming to help Nest resist Honeywell's dubious anti-competitive lawsuit.
http://www.theverge.com/2012/4/12/2942861/nest-answers-patent-lawsuit-honeywell-troll
Here's the full list of Honeywell's patents Nest thinks are invalid or irrelevant, and why:
#7,584,899, which covers a rotating ring around a central display. Nest says this was "implemented years earlier by engineers at Volkswagen," who filed for a European patent.
#6,975,958, which covers controlling a thermostat through the internet. Nest says this was already covered by now-expired patent #4,657,179, which Honeywell first filed for in 1984 a patent it did not disclose to the Patent Office.
#7,476,988, which covers "power-stealing" to charge the thermostat's battery from the control wires. Nest says Honeywell already patented the idea ten years prior in patent #5,736,795 and once again didn't tell the Patent Office.
#7,159,790, which covers a rotating selector with an offset rotation axis. You guessed it: Nest says Honeywell filed for exactly the same thing nearly 20 years prior, resulting in patent #4,405,080, a patent Honeywell didn't disclose to the Patent Office.
#7,634,504, which is Honeywell's wild patent for using natural language prompts to program a thermostat. Nest says this is a retread of patent #5,065,813, which was filed 15 years earlier and not shown to the PTO by Honeywell.
#7,142,948, which covers displaying the time it'll take to reach a certain temperature. Nest says that was already covered by patent #6,286,764 and #5,767,488 patents that were again not disclosed to the PTO.
#7,159,789, which covers a thermostat with a rotatable selector dial partially hidden behind a non-moving cover. At this point you should be ready for this: Nest claims this was already covered by patent #5,224,649, which Honeywell did not disclose to the PTO.
I hope Nest turns the controls industry on it's head. There is so many overprices beige boxes out on the market that are pieces of junk.