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Google Nest Learning Thermostat review: Can new tech work in an old house? We've got answers

ZDNet's long-term review of Google's 3rd-gen smart thermostat includes information on how to install it and what to expect when you put it to use.
michael-gariffo
Written by Michael Gariffo, Staff Writer on
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Google

Google's Nest Learning Thermostat has been around for some time now, yet it remains one of the top contenders in the smart thermostat space. Like many that choose it, I was attracted by its clean, high-end aesthetics and the promise of being able to have more granular control over not only my heating system, but the temperature of individual rooms in my home.

It's important to note that, despite being attracted by the Nest's promises, I was hesitant at first about the integration process. I live in a home that's over 120 years old. Obviously, the heating system is much newer, but it's still what I'd call pretty geriatric. The idea of connecting a Wi-Fi enabled, AI-using, smart assistant-communicating thermostat into my home and expecting it to work perfectly with a heating and cooling system that was installed over 20 years ago caused a kind of cognitive dissonance that made it hard to believe this could possibly go well. 

Although the installation process wasn't without the occasional bit of confusion, it was surprising in many, almost universally, positive ways. I won't spoil the ending, but I have a new appreciation of just how well cutting-edge systems can be designed to integrate into legacy infrastructure, when designed correctly.

Pros
  • Clean, simple aesthetics
  • Wide-ranging compatibility, even with older systems
  • Excellent voice assistant support
  • Reliable automated temperature control
Cons
  • Lack of granular notification controls
  • Initial training can result in some chilly/sweaty times until it gets a grip on your preferences

Let's take a look at how the Google Nest Learning Thermostat performed during its initial setup and my first six months of using it to gain a new level of control over my home's climate. 

Pre-Installation

Yes, there is a step even before we get to the installation, and it will become clear soon why it is so important that you don't skip this one. 

My initial apprehension over integrating a smart thermostat into such an old system led me to Google's Thermostat Compatibility Checker. This simple online tool runs you through a series of questions that can be answered by removing the faceplate of your old thermostat and taking a look at the wires connected there. I was expecting my hopes to be dashed by what lay hidden within the confines of my analogue, yellowing-plastic, 1980s era thermostat.

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Not my exact model of decrepit thermostat, but you get the idea...

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However, to my surprise, after inputting the various wires and colors found behind the aged thermostat's faceplate, I was told my home's system was compatible with the Nest Learning Thermostat, as well as the newer, lower cost Nest Thermostat. While I considered both, I eventually settled on the Nest Learning model due to its support for the Google Nest Temperature Sensor, an extremely important component in my goal of making every room in my home equally comfortable. We'll talk about these in more depth later. 

With Google's blessing given to my heating and cooling system's compatibility, I moved forward and ordered the Nest Learning Thermostat and a pair of Google Nest Temperature Sensors to place in two particularly problematic areas of my home. 

Installation 

Google provides everything you need to install the thermostat in your home, up to and including a surprisingly nice screwdriver with a reversible flat-head/Philips-head bit. Once you've turned off the breaker powering your old thermostat, it's just a matter of removing the needed wires, followed by the old unit's mounting plate. With that done, the installation truly begins. 

As someone that lives in a home that never quite has a stud in the wall where I need to hang something, I was pleased to see Google included self-tapping screws that were designed to anchor it to both wood and drywall. The fasteners screwed in easily using the included driver, and firmly held the included mounting unit with its permanently labeled wire fasteners. Making sure it was level was easy thanks to the thoughtful, built-in bubble level just below the top screw. 

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Michael Gariffo

The next step was getting the wires clipped into their correctly color-coded slots. This was a bit finicky due to a combination of the very low-profile nature of the mounting plate and residual bends in the existing wires from their many years spent wrapped around the old thermostat's screw contacts. Eventually I verified I had enough extra slack in the wire and chose to clip the kinked ends off and use a straighter portion to better seat into the Nest's spring-loaded, pushbutton contact clamps. Once I did this, it was easy to clip all of the necessary wires into place. 

This is a good time to talk about the "C" wire, or the common wire (seen above). Not all home heating and cooling systems have one of these run to their thermostats. If yours doesn't, Google sells a small adapter called the Nest Power Connector which can avoid you having to run a C wire through your walls by providing the voltage it would carry via one of the other wires already traveling to your thermostat. 

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Google

However, the Nest Learning Thermostat is unique in Google's smart thermostat lineup in that it does not always require a C wire to be present. Instead, it can "pulse" your system on for a minute or two at a time in order to sip a bit of power for itself from the wiring to maintain its necessary charge. That said, I've run into scattered reports of Nest owners having issues with this actually providing enough power, while others complain of the annoyance of having their systems go on and off for no reason. 

Also: Nest Learning Thermostat vs Nest Thermostat: Which is right for you?

I do not have a C wire, and, spoiler alert, have had no issues with the Nest Learning Thermostat maintaining sufficient power. Of course, if you choose the less expensive Nest Thermostat, or are more sensitive to your heating or cooling systems coming on randomly for a few seconds, you may need to install a Power Connector after all. 

Initial setup

Once you've completed the installation of the base plate, it's just a matter of clicking the faceplate over it and restoring power to the heating system wiring, which now includes the Nest. This will begin a several-minute-long process during which the thermostat connects to your Wi-Fi networks and asks for a few initial settings such as its location, what type of heating and cooling system you have, and a few other basics. These can all be completed on the thermostat itself using the outer ring that rotates to scroll through selections and clicks in to confirm them. 

This is when you would install any additional sensors you'd like to use with the Nest. In my case, this meant adding two more devices to my setup process: the pair of Nest Temperature Sensors.Thankfully, these are much easier to set up. Just pull out the battery activation tab on the small sensor units and place them in a convenient location within the room you'd like to monitor. They can be placed on a flat surface or wall mounted with a similar type of self-tapping screw, like the ones the main unit includes. 

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The sensor unit is about the diameter of a large wristwatch face and about one inch tall (quarter for scale)

Google

Once placed, the next step is to tap the "+" icon in the Nest app. Once that's done, you'll have to tap in a location name, make sure the unit can connect to the Nest Thermostat wirelessly, and you're good to go. In my experience, the sensors do an excellent job of accurately reading the ambient temperatures in their room of choice, just be sure to avoid any areas with strong direct sunlight or cold drafts for the most accurate readings. 

The only downside I've discovered with the hardware of the remote units is that it cannot provide readings on humidity like the thermostat itself. It's a minor gripe, but one that comes up frequently in the cold winter months when the lack of indoor humidity, as well as the dry sinuses and static shocks that go along with it, may be something you want to track. 

The user experience

Now that all the hardware's in place and the initial setup is complete, you get to actually enjoy the benefits of owning a smart thermostat. The first perk is in the name itself. The Nest Learning Thermostat is designed to do just that, learn. In my experience, it's done an excellent job of tailoring heating in my home over the past fall and winter to keep the whole house comfortable. 

Importantly, the Nest can be set to use the temperature at the thermostat itself, or at any one of its connected sensors to be the one it uses to trigger the heat when needed. This means that if you spend your days in a drafty home office, like I do, you can create a schedule within the Nest app that will automatically use that drafty office's sensor to make the heat kick on each morning, at the time of your choosing. This will let you have the room nice and toasty by the time you've got to make the long commute across the hall to plant yourself at your desk for another workday. 

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The app will also let you know which sensors tend to be coolest or warmest, once it analyzes your home's trends

Michael Gariffo

If you live in a perfectly insulated, newly built home, the vast differences in temperatures some of us have to deal with may be shocking. But, for example, I've had the temperature sensor in another room read 72 degrees while the aforementioned office, which is right across the hall, is at a frigid 58 degrees due to differences in insulation, sunlight received, and wind direction. Being able to manually or automatically account for this differential by choosing one sensor or the other has meant far, far fewer days spent unnecessarily sweating or shivering. 

Better yet, the tendencies that you show the Nest you'd prefer over the course of using it are integrated into its self-programing measures, which attempt to balance your comfort with energy savings that can lower your utility bills and help reduce your home's carbon footprint. 

While this has all amounted to a vastly improved living experience compared to the yellowing plastic analogue thermostat the Nest replaced, the transition has not always been 100% smooth. 

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Michael Gariffo

One of the most common issues I've run across is the Nest's seemingly nonsensical determinations that it could go into "Eco" mode at certain times of day. This mode drops your thermostat's temperature to something lower than usual, in my case around 66 degrees. This is below the minimum temp of 68 degrees I'd set (as you can see above), and often occurred during times when the Nest should have been able to tell I was very present and likely in need of heat. The result can be a bit on the chilly side, especially if you prefer to lounge around in short sleeves. Thankfully, the longer my Nest has been in operation, the more its learned to understand when this is and is not ok, resulting in its temperature settings being something I rarely have to think about anymore. 

The other matter I've run into has specifically to do with the Nest Temperature Sensors. Although these units are absolutely vital to the increased comfort I've mentioned, Google's Nest app seems to have been designed by someone that thinks all homes are of the newly-built, perfectly-insulated variety I mentioned earlier. I say this because on unusually windy or cold days, I am inundated with Nest App notifications informing me that my system is running a a lot, and asking me to consider moving the sensor in a given room. 

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Oh boy, this again!

Michael Gariffo

Now, being a (relatively) logical person, I would assume Google's engineers would understand sometimes it's just damn cold, and the heat needs to run a lot to keep things comfortable. I'm sure any readers in more northern climes can relate. But, not only has the Nest platform seemingly never gotten the gist of the fact that I don't want to move the sensor, but it continues sending me these notifications two at a time, every time, for some inexplicable reason. 

Of course, you can block notifications from the app entirely on iOS or Android, but this would mean actual important notifications might not make it through to you. That's especially problematic if you've bought more deeply into the Nest ecosystem with one of Google's doorbells or cameras, which absolutely rely on those same notifications to inform you of visitors or intruders…hardly the kind of messages you'd be okay missing. 

It's a minor annoyance, and one I've decided to live with. But, nonetheless, it's something Google should allow the user to disable at will. Unfortunately, that setting does not appear to exist. 

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The far more simplified control screen the same Nest Learning Thermostat presents in the Google Home app

Michael Gariffo

One of the reasons for this lack of ongoing improvements to the Nest App may be Google's continued efforts to transition away from it to its own Google Home app. This hybrid, almost split-personality approach the company is taking to controlling its Nest-branded hardware means that the Google Home app can currently control things like the Nest Learning Thermostat or Nest Hello Doorbell, but most of the full capabilities of either device still require the Nest app itself to access. 

In the future, I'm sure Google will eventually transition all settings to its Home app. But, in the meantime, the dual nature of managing your Nest-branded devices is an ongoing drawback. 

Voice assistant compatibility

This is a big one for me, and for a lot of other potential buyers, I'm sure. To get right to the point, the Nest Learning Thermostat has worked nearly flawlessly with my Alexa-enabled devices from Amazon, and completely flawlessly with Google's own Google Assistant-enabled smart speakers. You can use either platform to find out the current temperature, change your desired temperature, and perform other basic functions. 

Unfortunately, you cannot switch your thermostat's active sensor to a Nest Temperature sensor, nor can you retrieve the current temperature at any one of those units from the voice assistant. This means controlling your heating or cooling via any of the remote sensor units typically involves either pulling out your phone or walking over to the main thermostat itself to fiddle with settings. Not ideal, but, as I mentioned above, it's something I've felt the need to do less and less frequently as the Nest has gotten a better grip on my daily heating and cooling preferences.

Siri, as you may have guessed at this point, is not compatible with the Nest Learning Thermostat out of the box. While it is possible to make the device work with Apple's personal digital assistant, doing so requires buying a third-party solution that can serve as a go-between to connect the Nest platform with Apple's HomeKit platform. Given the prevalence of Google and Amazon-branded devices already available in my home, it's not something I've pursued, but it is available as an option if you are one of the few users out there entirely locked into Apple's HomePod ecosystem, or a person that relies exclusively on your phone to control your smart home devices. 

Wrap-up

I think one of the best questions to ask a reviewer is always "would you buy it again?" In this case, the answer is an emphatic yes. In fact, I did buy it again when I purchased another Nest and another pair of temperature sensors for the other floor of my home with its separate heating and cooling zone. Like the first, it's worked extremely well, and unfortunately replicated all of the same minor annoyances.

It's always possible that Google's quietly preparing a true successor to the Nest Learning Thermostat. After all, the device is already on its third iteration. But, until the company finally comes to market with an alternative as fully featured and consistently reliable as the still Nest-branded option has been for me, I'd recommended sticking with one of the first, and still one of the best, smart thermostats out there. 

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