Friday, January 25, 2013

Nest Thermostat - Quick Review

Nest Programmable, Learning Thermostat - Quick Review.  Updated with new comments after a year's use.

I bought a new Nest brand thermostat for my furnace / AC, replacing my old Mercury-filled thermostat that I've used for the past 23 years.

Everybody who has bought one of these will tell you how neat they are.  I agree.  This is about the most fun you can have with a mundane household appliance.

What you will find is the thermostat is easy to use, thoughtfully designed, magically functional, and artful.  High praise, deserved.

Unbelievable Features first:
  • Connects to the Internet (yes!)
  • Downloads updates and patches itself when first started
  • Analog controls - turn the dial to adjust the heat - no buttons
  • Screen turns red when heating, blue when cooling
  • Always shows status (such as "in 20 minutes, heating to 72deg)
  • It 'learns' your schedule and programs itself
  • It connects to your Android or iPhone - adjust from anywhere
  • Motion detector, turns down heat if nobody is home
  • The cat does not appear to trip the motion detector
  • It knows the outside temperatures and adjusts its schedule

This is a programmable thermostat with no buttons or programming.  The thermostat "learns" how and when you set your temperatures -- basically 'figuring' it out as you go.  The Vendor claims that (90%) of all programmable thermostats are not programmed properly; this thermostat fixes that problem.   

In our case, after three days, the device had decided our patterns and had programmed itself.  We usually wake at 6:00am, last one to leave for work is at 8:30; someone comes home by 4:30 and we go to bed at 11:00.   On the Android, the reported schedule looks something like this:

For the first few days, we adjusted the temperature the way we like it.  It figured out the rest.  After a short time, it even calculates if it needs to turn the heat on earlier than normal if it is particularly cold outside. 


The thermostat has a stainless-steel ring, which rotates around the glass-front.  The device, about the size of hockey-puck, feels solid and substantial.  It is heavy for its size.  The thermostat is composed of two basic parts:  the thermostat and a snap-on wiring harness.

The wiring harness is logical and installs with two lag-screws (illustration, below) and it has a bubble level. If hanging on sheetrock, without a stud, I would use plastic sheetrock anchors, which were oddly not included.  In my case, I was mounting on a wooden wall and had no concerns, but the device does come with several optional mounting plates, should you need to cover a junction box or if you have a gaping hole from the old thermostat.  It even comes with a screwdriver.

Once the harness is attached to the wall, the hockey-puck-electronics snap onto it with a click.

It comes beautifully packaged, but with little documentation. The web is the real resource.  With that said, I installed and configured it without really reading any of the instructions.  It is a self-guided installation, but you will want to go to the web and use their automatic wiring-diagram.


Installation was do-it-yourself easy.  Follow these steps:
  • Remove the old thermostat's cover
  • Record which wires went-where on the old thermostat.  They are always labeled as "G" (green), R, Y, RH, etc.  Ignore the actual wire colors.
  • On the installation site, check the labeled boxes (R, G, Y, RH) - the wire-names you have.  It then gives you a wiring diagram, and confirms the thermostat is compatible with your furnace (98% are).

  • My Wiring Diagram looked like this (literally displayed like this on the web):

  • Turn off the breaker to the furnace/AC
  • Remove wires from old thermostat
  • Screw new wiring harness to the wall and pull wires through center
  • Insert wires into the push-connectors
  • Snap the thermostat onto the harness; power-up
  • Pat yourself on the back for a job well done

I had a momentary confusion because my old thermostat forked the red wire from the "R" connector to "RH", giving me four wires at five connections.  The Nest does not care or need the jumper, all I had to do was plug into the RH, exactly per the wiring diagram on their website.  Also, be aware the wire on your old thermostat may have been labeled G "green" but the actual wire color could be something different -- ignore your actual wire color and only pay attention to the old-thermostat's printed labels on its wiring harness.

The thermostat is powered by the existing wiring (24-volt); no additional power is needed.

Be sure to take the old Mercury-filled thermometer to a hazardous waste dump - Mercury is nasty stuff and must not be thrown in the trash. 

When it wakes up, it shows all of the local wireless networks (or you can type your SSID); choose your network, type the password (the round dial has a way to type individual letters; a third-grader can figure this out, it is really easy), and it connects.  Once online, it downloads new BIOS versions and walks you through various questions, such as what is your zipcode (it uses this to determine the local temperature), what type of heating you have (forced-air, gas, electric, infloor, etc.) and a few other minor questions.   Once you are done, the thermostat is ready to use.

Although the thermostat does not need an ethernet connection to work, why would you buy one of these without it?  The wireless is what makes this so neat.  I would not use this thermostat without a wireless connection. 

Smart Phone Installation

Optionally, from your App Store, install the NEST application.  Create an online account, where they ask for an email address (acting as an account name) and password.  As soon as you do this, your phone will tell you to walk up to the thermostat and press "Ok".  The two devices automatically connect.

Immediately, from your phone, you can adjust the temperature, and later in the week, after some history, you can view reports on when your furnace and A/C are turned on and what temperatures were set in the house at any hour.  It is embarrassingly easy to use.

Total hardware installation time was about 5 minutes.  Waiting for software updates and setting up the wireless was another 20 minutes and 5 minutes for the Android phone setup.  Complete, fully functional time was about 30 minutes.  Amazing.

The phone is handy
The other day, I left work early and from my phone I turned the heat up to 71 degrees so the house would be warm by the time I arrived.  What a hoot.

Once a month, Nest emails a report showing energy use.


  • These are somewhat expensive devices, costing $250, but it should save money.  I've not compared last year's energy use with this year, but the device appears to be working as advertised.  It clearly has been turning off the AC (or furnace) when we are away and the schedule has been working exactly as hoped.  I would guess the payback might be after a couple of years.  But that is hardly a reason not to install one.  They are too much fun and have monsterous bragging rights.

Installation is easy.
Operation is transparent.

This is a recommended device.

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