# Should I get a "smart" thermostat? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [July 2, 2017, 5:42pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374 "2017-07-02T17:42:03Z")\ **Posts on this page:** 11\ **Page:** 3
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [July 6, 2017, 12:00am UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/41 "2017-07-06T00:00:36Z")
> [@John\_Mace](#): > > That’s an important thing to consider when buying a new thermostat. Check before doings so in case you have to run extra wire. Not everyone is going to want to do that. Nest claims that the c-wire is desirable, but not necessary, for their device: > [@](#): > > C-wire is not required > > A c-wire (also referred to as a common wire) is a low voltage power wire that many modern thermostats require for their features to work. > > This Nest Learning Thermostat does not require a c-wire to work. Nest has a built-in battery that can be charged using the heating and cooling wires. > > Nest however recommends that you connect a c-wire if you already have one. To determine if you have a c-wire, please remove your old thermostat’s cover plate. You should see several wire terminals labeled with letters. If a wire is connected to the “C” terminal, you have a c-wire. [https://www.comedmarketplace.com/collections/wi-fi-thermostats/products/3rd-gen-nest-learning-thermostat-white](https://www.comedmarketplace.com/collections/wi-fi-thermostats/products/3rd-gen-nest-learning-thermostat-white) ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [July 10, 2017, 7:47pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/42 "2017-07-10T19:47:53Z")
Well, in case anyone was curious, I \*did \*get the Nest, for just under a hundred bucks. It was very easy to install, even without a c-wire. And no, I probably won’t use 75% of what it can do, but the coolness factor is well worth it for that subsidized price. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 10, 2017, 8:25pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/43 "2017-07-10T20:25:46Z")
Cool. (or Warm :)). Thanks for the update. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [July 10, 2017, 8:36pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/44 "2017-07-10T20:36:07Z")
When you have no common wire at the thermostat to power a Nest, it somehow bleeds off a little of the 24 volts running through when it’s calling for heat/cooling to charge up the internal battery. This has two disadvantages: if you go months without heating/cooling (like my heat-only setup in summer) the battery can go completely flat, and additionally some HVAC systems don’t seem to play nice with it. Lots of people seem very down on the idea of these thermostats, but I quite like mine. I initially got it primarily because the old thermostat did a crap job of regulating the temperature in my house. It’s an old house heated with hot water radiators. The system is slow to begin heating after being activated, and slow to stop heating after being shut down. Because of this, the dumb thermostat would kick on too late, and wouldn’t shut off soon enough, so it would be uncomfortably cold before the heating really kicked in and then it would overshoot to uncomfortably warm (because the rads are still full of hot water when the thermostat decides to kick off). The Nest has a radiant heating mode that is supposed to understand that the system has this sort of delay built into it, and it does actually work, mostly. Certainly it maintains a vastly more stable temperature than the old thermostat. It’s also pretty good at predicting time-to-temperature based on past performance and current weather data, which enables me to use significant workday and nighttime temperature setbacks without suffering long periods of cold when I get up/back from work. As slow as my radiator system is to heat in extreme cold weather, without this sort of feature it would be a giant pain in the butt to do any money-saving thermostat scheduling at all. Finally, the ease of modifying the schedule is something I make use of all the time. Most cheap programmable thermostats are awkward enough to program that you’re going to set them once and almost never change them again. For day to day variation you’ll just manually adjust the thermostat. But if I know that tomorrow I’d like the heat on a slightly different schedule, I’ll pop open the webpage and change it. I don’t use the self-learning scheduling or occupancy detection at all, but the other aspects I’ve come to depend on. If you stole my Nest, I’d immediately replace it (albeit possibly with an Ecobee). Well, before October, anyways. ---
**Author:** ![Runs\_With\_Scissors](https://avatars.discourse-cdn.com/v4/letter/r/278dde/32.png) [@Runs\_With\_Scissors](https://boards.straightdope.com/u/Runs_With_Scissors)\ **Post date:** [July 10, 2017, 9:02pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/45 "2017-07-10T21:02:03Z")
I have one (not a nest). I love it. It’s especially useful in the winter when I’m on vacation and want to return to a warm house. It’s also nice to tell it to warm the house if I’m coming home early. Sometimes I get up earlier than it’s set to turn the furnace on, but I still want to be in bed for a half hour. It’s kind of embarrassing to turn the heat on without getting out of bed, but if you have ever enjoyed this simple luxury, you won’t judge me. Sent from my SM-G935V using Tapatalk ---
**Author:** ![Driver8](https://avatars.discourse-cdn.com/v4/letter/d/b5a626/32.png) [@Driver8](https://boards.straightdope.com/u/Driver8)\ **Post date:** [July 10, 2017, 9:38pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/46 "2017-07-10T21:38:34Z")
> [@Gorsnak](#): > > When you have no common wire at the thermostat to power a Nest, it somehow bleeds off a little of the 24 volts running through when it’s calling for heat/cooling to charge up the internal battery. This has two disadvantages: if you go months without heating/cooling (like my heat-only setup in summer) the battery can go completely flat, and additionally some HVAC systems don’t seem to play nice with it. Does it go completely flat? My reading ([When the Nest Learning Thermostat needs a common “C” wire](https://nest.com/support/article/When-Nest-needs-a-common-C-wire)) was that it would potentially switch on your heating and cooling system just for the purpose of powering itself. Just the possibility of that would have been a deal breaker for us, which is why I stole the fan control wire for this purpose. That obviously has its own disadvantages but not ones that have inconvenienced us specifically. ---
**Author:** ![Gorsnak](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gorsnak/32/7587_2.png) [@Gorsnak](https://boards.straightdope.com/u/Gorsnak)\ **Post date:** [July 10, 2017, 9:53pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/47 "2017-07-10T21:53:14Z")
> [@Driver8](#): > > Does it go completely flat? My reading ([When the Nest Learning Thermostat needs a common “C” wire](https://nest.com/support/article/When-Nest-needs-a-common-C-wire)) was that it would potentially switch on your heating and cooling system just for the purpose of powering itself. > > Just the possibility of that would have been a deal breaker for us, which is why I stole the fan control wire for this purpose. That obviously has its own disadvantages but not ones that have inconvenienced us specifically. I can’t say for sure, but you certainly could be reading that correctly. I just ran a new wire for mine - not a big deal for me as that sort of thing falls within the scope of my professional skills, and I had to rejigger the wiring anyways - my old thermostat directly switched 120VAC to the circulation pump. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [July 10, 2017, 10:21pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/48 "2017-07-10T22:21:07Z")
> [@Gorsnak](#): > > When you have no common wire at the thermostat to power a Nest, it somehow bleeds off a little of the 24 volts running through when it’s calling for heat/cooling to charge up the internal battery. This has two disadvantages: if you go months without heating/cooling (like my heat-only setup in summer) the battery can go completely flat, and additionally some HVAC systems don’t seem to play nice with it… Little danger of that in Chicago where I live. We only have two seasons: too damn hot, and too damn cold. Sometimes during the same day! ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 11, 2017, 12:35am UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/49 "2017-07-11T00:35:16Z")
Yeah. When I lived in St Louis I enjoyed the shoulder seasons. But at the same time it drove me batty to need to run the AC in the afternoon and the heat all night. It’d sure be neat to have some way to store up the excess that Mother Nature so generously provides for just 12 measly hours to avoid paying to go back the other way … again. And again. And again. Sigh. ---
**Author:** ![swampspruce](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/swampspruce/32/261_2.png) [@swampspruce](https://boards.straightdope.com/u/swampspruce)\ **Post date:** [July 11, 2017, 3:50pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/50 "2017-07-11T15:50:51Z")
[Solar thermal battery](http://www.ecohome.net/guide/thermal-batteries-storing-solar-heat) ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [July 11, 2017, 4:51pm UTC](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374/51 "2017-07-11T16:51:41Z")
Certainly there _are_ answers today. They are not however standard features of standard US tract housing. Perhaps they should be in the regions that would benefit from them. [Previous page](https://boards.straightdope.com/t/should-i-get-a-smart-thermostat/790374.md?page=2)