Great, simple, wifi thermostat.
932288
Put this in my mother-in-laws house, she absolutely loves it!  Who needs a fancy Nest when all you do after installing a wifi thermostat is control it with your smart phone?  Heavily thinks about selling my nest that acts finicky with my router and getting one of these for our house too.
4351973
This is my 2nd purchase of this wi-fi thermostat and I'm very pleased with the results so far. The first one was purchased about 2 years ago and was the typical $99 but the one installed today only set me back $79 BUT I was surprised that for the first time in probably 15 years of using Amazon, I was charged sales tax. That ride was bound to come to a stop sooner or later. Oh well, still can't beat the great prices and free shipping on most items and I'll continue to use Amazon as much as possible.

Anyway, the reason you're reading this is to gain some clue as to what/how to get that dreaded "C" wire that is required to operate this device in wi-fi mode. I realize all systems/set ups are different but in my case, I did have at least 1 or 2 spare wires on the existing thermostat wire and was ultimately able to connect that extra wire to a 24V continuous connection within the air handler or heating unit, if you prefer. I'll admit, the one I installed a couple years ago was a real test of my wits and my will. Conservatively, if I count the time researching the internet and climbing in and out a dozen times to where the gas furnace resides, it took me about 4-5 hours...I know, ouch, but I've found the convenience of adjusting the thermostat from anywhere in the world to be well worth it, hence the 2nd purchase for our downstairs unit that was installed today. Redemption was had when I met the mailman today and had my new unit mounted, wired and working in about 30-35 minutes, start to finish! What was my secret? The set up was very closely matched to the work I did a couple years ago and with just a little luck on my side, I connected the extra C wire to the correct wire nut right off the bat. This unit is an old school hydronic system (uses hot water to provide the heat for the house) matched to a conventional AC condensing outdoor unit so I wasn't so sure but again, all systems go in about 30 minutes.

In a nutshell, you have to connect that C wire, assuming you have a spare wire already in your thermo wire, to 24v continuous electrical supply in order to power and run this thermostat. I'm sure electricians and AC guys may find this amusing and could do something like this blindfolded but for a commoner (there's that C reference again), this was a major score to get this one running quickly. Love it!
4791099
I love this thermostat.  Its no frills but since it is Z-wave, it works well with my SmartThings system.
3389099
We replaced an old (18 years) thermostat for our heat pump at a very reasonable price. We don't need one that is programmable and this works just fine. Easy to read and simple to understand the controls.
4686174
My conventional HTC system already used 5 wires so I knew this thermostat woul work. Here's what I did:

Turn off power to air handler and the AC
Took off old thermostat.
Take photo of current wiring on old thermostat
Remove wires from the jumpers.
Remove old thermostat panel
Labelieve wires with provided stickers
Put on new thermostat panel
Insert wires into the jumpers.
Push the new thermostat unit onto the panel.

Product worked right away.  Setting up the wifi took 5 minutes and was simple. I downloaded the easy to use honeywell app onto my iPhone.
3055688
This venstar thermostat is awesome this is my second one that I bought. The new upgrade for the WiFi is a lot better than the last one, so it makes it easier for the updates
438616
The perfect smart thermostat.  I bought this one because of the remote sensors.  Our heat pump only has one zone, so the upstairs wasn't consistent with the downstairs.  We only have one sensor so far and it's already a HUGE improvement.  I will buy more sensors, but honestly we wouldn't need more.  It's already a big improvement and it's so easy to use.  The app makes it super easy to use as well. I can change the temp from bed using my phone or while I'm at work our on my way home.  Highly recommend this one!
4803743
So far so good. It was easy to setup and the signal is great. Wish it was closer to the 10,000 sq/ft mark, but I understand the household restrictions of wifi and am ok with it.
4173629
Works just as designed over wifi, gives great stats with the right apps.
3958772
Just installed this thermostat after becoming very very frustrated after three+ hours with the $200+- wifi model.  This one installed very easily (10 minutes), seems to be working like a charm, and was half the price.  I may go back and try the wifi model later but for now this is just fine...
1049058
What a simple device and so easy to install. Weather was cool when it was installed so the ability to adjust the setting lower came in handy and provided proof the unit worked. Since installation, it has provided power to an exhaust fan every time the temperature setting has been reached. Since it is "hard wired" the installation of a three way switch may prove handy in case you want to turn it completely off or bypass it for continuous operation.
4977716
I purchased this thermostat after watching TWIT's Try Before You Buy podcast.  It was recommended, and as we weren't happy with our existing programmable thermostat, we decided to try this.  As reported, installation was great.  The kit comes with a handy screwdriver and wall plate.  I used both, and this install looks nicer than my previous did.  The wiring install was relatively straightforward with one glitch.  The kit did not have stickers with all of my wire labels (ie mine differed slightly from the labels) amid inadvertently labelled one wire wrong.  Also we had a jumper cable, and it wasn't immediately clear what to do about that.

Wiring went in easily.  I searched Nest's site on what to do about the jumper, and easily found the remedy (Nest says it detects that you need a jumper and takes care of that electronically).  Because I had mislabeled one wire, when we booted the thermostat, it said I had a heat pump and no a/c (wrong). Took a quick look at the digital pic I had of my old setup (protip - take a picture of your wiring before messing with it!) and realized my mistake.  Reinserted the wire in the correct slot and bingo, we were in business.

Connected to my wifi easily enough (do check the Nest's website, there are some routers that the Nest doesn't cooperate with and this can be a big issue).  Set my locality, the thermostat downloaded software updates and it was running fine.  It has taken a few days to get the full feature set - the nest has to learn your system to estimate heat up and cool down times.

I like the app - it provides quite a bit of consumption information, such as how long your furnace ran on a given day.  We have made use of the away function (setting the furnace to a minimum temp while away) and the scheduler.  The scheduler is excellent and very flexible.  Each day can have a different schedule, or you can let the auto scheduler handle things for you.

One note, the nest uses a rechargable battery that leaches from your main control line.  If your furnace/ac does not support that, you probably can't use the nest.

Overall, I love the interface.  It is simple and much more friendly than the replaced thermostat. I take one star away for price.
2036595
Very nice, Simple, (once I got it working)  at first it would not connect to the wifi at the installation site, I brought it home it worked just fine, back at the site it finally started working and I'm not just sure why.  but it has been working really nice now for several months. Simple and does the job, I'm ordering another one.
1551575
Easy to install, nice to be able to adjust things from your smartphone and to get reports when it starts and stops. As long as it can access your WiFi hot spot you're in.
592767
This lovely thermostat is a good buy. Fairly easy to install (although make sure you differentiate the "r" wire from the "RC" wire during set up!). The touch screen is easy to understand and it is easy to program, too. Nice to be able to walk by and see the time prominently displayed, too. Overall, would recommend!
1089696
I'm not sophisticated enough of a user to run temperature tests and understand the physics of heat transfer and its impact on systems.  But I'm not a novice user either.  This is my third or fourth router in the past 15 or so years, and I bought it because we're increasing the number of devices we use around the house, with at least three devices connected at any time.  And we're also increasing the places where we need access around the property.  In the two years I've owned this, it's performed flawlessly.  It was simple to configure and it's been simple to upgrade and maintain.  The dual band works fine, and the devices that we have that can access the higher band perform well on it.  The places that are distant to the router perform well on the lower band.  It's good when something I buy actually performs as advertised, and this does that.  A simple router that allows me the level of wireless access I need.  No router is plug and play, but this is about as easy as they come.
2740819
The Thermostat works as expected. I had to connect to its ad-hoc network and then connect it to my WiFi, and register it to a new account with Honeywell, so the set-up took a little bit of time, but the thermostat is well worth it. I can schedule my temperature and monitor it from anywhere.