See what changed from the first Nest to the current model.

Nest is a company that's been around a while and since the debut in 2011, there have been three generations of hardware. Because a thermostat is something we tend to keep once we buy one there are plenty of older generation units in use and for sale used. While the changes between them aren't as drastic as what we would see in a smartphone, there are some differences worth talking about.

We'll start by talking about what hasn't changed: the overall user experience. When Google bought Nest Labs many were worried that there would be significant "over-engineering" and extra features added that take away from the simple and efficient experience Next delivers. Thankfully, that didn't happen and using a first generation Nest feels very much like using a third generation Nest, even though there are some substantial changes in functionality and compatibility.

Which Nest do I have?

Nest technical info

Each generation has a different diameter and thickness, though the differences are very slight. One of the external differences you can easily see is in the trim ring. A gen 1 Nest has a two part ring in stainless steel, and a gen 3 Nest can have a copper, white or black ring. Another external difference is the size of the display, with the generation 3 Nest having a larger (.5 inch difference in diameter) touch screen that the previous models.

You don't have to break out any measuring tools to tell which Nest is on your wall. Just open the Nest app, choose your thermostat and in the upper right corner tap the gear icon to open the settings. Under Technical Info you'll see the Display Model listing. The first digit in the model number corresponds with the hardware version.

Here is a quick overview of the main differences

Category Nest Gen 1 Nest Gen 2 Nest Gen 3
Dimensions Diameter 3.20 inches
Depth 1.44 inches
Diameter 3.27 inches
Depth 1.26 inches
Diameter 3.25 inches
Depth 1.21 inches
Display 2.75 inch (diameter)
320 x 320 px
2.75 inch (diameter)
320 x 320 px
3.25 inch (diameter)
480 x 480 px
Connectivity 802.11b/g/n @2.4GHz
Zigbee @2.4GHz
802.11b/g/n @2.4GHz
802.15.4 @2.4GHz
802.11b/g/n @2.4GHz
802.11a/n @5GHz
802.15.4 @2.4GHz
Bluetooth LE
Sensors Temperature
Humidity
Near-Field Activity
Far-Field Activity
Ambient Light
Temperature
Humidity
Near-Field Activity
Far-Field Activity
Ambient Light
Temperature (10 sensors)
Humidity
Near-Field Activity
Far-Field Activity
Ambient Light
Features Auto-Schedule
Airwave
Nest Leaf
Auto-Away
Energy History
Time to Temperature
Auto-Schedule
Airwave
Nest Leaf
Auto-Away
Energy History
Time to Temperature
System Match
Early On
Heat Pump Balance
Auto-Schedule
Airwave
Nest Leaf
Auto-Away
Energy History
Time to Temperature
System Match
Early On
Heat Pump Balance
FarSight
Water / Boiler control

Changes in gen 2

The biggest difference from the first generation to the second was equipment support. When Nest first arrived it was compatible with approximately 75% of heating and cooling systems in use. That means there were a sizeable number of people who couldn't use a Nest. Gen 2 brought that number to 95% by adding an extra pair of connectors. The new inputs added support for hybrid heat installations and humidistats in addition to 1-2 stage cooling and 1-3 stage heating systems. One last change made it possible to control 24 volts equipment without a common wire back to the thermostat. These changes made it possible to use a Nest thermostat on advanced HVAC systems found in the newest homes.

Generation 2 brought support for more advanced installations and a more custom setup.

Gen 2 Nest thermostats also introduced System Match. System Match determines the wiring connection then asks you a few questions during the installation. This lets Nest tune other features specifically for your setup rather than treat every installation as a standard forced-air system and makes us more comfortable while saving money.

Additional features introduced with gen 2 include Early On mode for cold mornings, filter change reminders and a True Radiant mode that helps the thermostat determine exactly how much heat is being created.

Changes in gen 3

The biggest visible difference between previous models and the generation 3 model is the display. With gen 3 we see a bigger 480 by 480 touchscreen at 229 pixels per inch. This makes it easier to see information across the room so you don't need to open the app on your phone or tablet.

Generation 3 brings a better display and support for water boilers as well as more colors.

Not readily seen but more important are some additional features. Gen 3 Nests can control a water boiler if you have one in your HVAC system. Just like other environmental controls through Nest software you can set limits and schedules for when the boiler is heated and a peak water setting is useful as an override if you have guests or need to use some extra hot water.

Gen 3 also has what Nest calls Farsight. Using special sensors your thermostat can tell when someone enters a room or walks past from up to 5 meters away. There are several things you can display on the screen when a person is sensed, including a clock or a weather widget. Nest users coming home from work can see the current indoor temperature as soon as they walk into the house. You'll know at a glance if you need to adjust the temperature if you arrive earlier than scheduled.


A Nest Thermostat is a great way to keep your house at the temperature you want and save money while doing it. It's reasonably simple to install yourself (professional installation is about $125 if you want to go that way) and works with almost every heating and cooling setup. With full control from your phone or Amazon Echo and Google Home, it's a great first step for an automated lifestyle.

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