Reviews You Can Rely On

How We Tested Thermostats

Tuesday July 9, 2024

We meticulously tested every facet of these thermostats, even constructing a custom-made testing board for direct side-by-side comparisons of their functions. This board translated the thermostats' signals into control commands that would activate lights meant to indicate activation of the Heat, Cool, and Fan on an HVAC system, as well as activate actual portable fans, heaters, and ACs.

The front of our custom thermostat testing board.
Credit: Matt Lighthart

This enabled us to promptly repeat the test on each thermostat, ultimately leading to a more effective and direct comparison between the models.

thermostat - the backside of our testing board exposes the wiring to lights, fan...
The backside of our testing board exposes the wiring to lights, Fan, AC, and Heater rigged to test these thermostats.
Credit: Matt Lighthart

Ease of Use


When evaluating thermostats for their ease of use, we considered everything that makes or breaks a pleasant user interaction. First, high scorers need to make it easy and intuitive to adjust the temperature and switch between different modes. We appreciate responsive touchscreen controls with instinctive inputs and gestures or well-placed dedicated physical buttons for this. When it comes to smart thermostats, we also like to see polished user interfaces and advanced functions through a dedicated app.

We tested the accuracy of every thermostat's temperature reading against a lab-grade temperature-sensing data logger.
Credit: Matt Lighthart

Next up, we award points for advanced fan controls and some form of temperature holding. Some thermostats give you no control over the fan at all, while others let you decide if and when to run it and still give you the option to leave it on auto-pilot. Hold status is another function that we really appreciate when it is done right. The ability to bypass all scheduling and programming to hold a set temperature until you tell the thermostat to do otherwise comes in handy. Some thermostats have complicated ways of achieving this, while others are so simple that they just hold temperature by default.

thermostat - we encountered innovative interfaces throughout this testing.
We encountered innovative interfaces throughout this testing.
Credit: Matt Lighthart

Lastly, we award points for thermostats that are easy to read and display accurate temperatures. Some of the best thermostats will have highly legible screens that can activate or brighten as you approach them, and they will be highly precise with regard to the temperature displayed on the thermostat versus the ambient temperature measurement that we take with nearby lab-grade temperature loggers.

thermostat - typical install tools and testing devices used throughout this...
Typical install tools and testing devices used throughout this review included a level, drill, screw-drivers, and temperature sensors.
Credit: Matt Lighthart

DIY Installation


We rated the installation for every thermostat based on its technical complexity and how well the process was guided through supplied text and video. We highly preferred units that featured push-in wire terminals instead of the screw-in types. For many of the smart thermostats, extra points were awarded if we were guided through a dedicated app.

thermostat - we strongly prefer push-in terminal connectors to these screw-in ones.
We strongly prefer push-in terminal connectors to these screw-in ones.
Credit: Matt Lighthart

Some other nice-to-haves were online compatibility checkers, easy WiFi connectivity, and easy-to-create online accounts for smart thermostats. We also found it helpful when instructions would remind us to snap a picture of the wiring of the thermostat we were replacing and tell us what tools to bring for the job. We appreciate kits that include a built-in level for a precise installation as well.

thermostat - take a look at the accuracy of these thermostats vs. lab-grade...
Take a look at the accuracy of these thermostats vs. lab-grade temperature logging equipment.
Credit: Austin Palmer

Scheduling


We scored this metric based on the availability, intuitiveness, and robustness of scheduling features for every thermostat. The more flexible the scheduling capabilities, the higher the score awarded. For instance, we looked into the number of schedulable days, the ability to dial in intricacies, and the number and complexity of events permitted by the operating system.

thermostat - setting a schedule via an intuitive smart app can be the easiest way...
Setting a schedule via an intuitive smart app can be the easiest way to set up your scheduling.
Credit: Matt Lighthart

Smart Capabilities


Many thermostats we tested have some smart capability, but a few outliers kept it barebones and old school. Those did not score any points at all in this category, but we awarded points in a variety of areas for the others.

Most of the time, scheduling on a companion app is preferred, but a few more basic programmable thermostats did a good job with scheduling, too.
Credit: Matt Lighthart

The highest scorers had an easy-to-navigate mobile app and geofencing, where the thermostat can track your presence in or proximity to your home to trigger heating and cooling events. We also assessed and awarded points for maintenance reminders, schedule learning features, and the number of smart home ecosystems the thermostat is compatible with (Amazon Alexa, Apple Homekit, Google Assistant, Samsung Smart Things, etc.).

thermostat - remote access is a huge convenience afforded by smart thermostats.
Remote access is a huge convenience afforded by smart thermostats.
Credit: Matt Lighthart

Energy Saving


The final assessment is made regarding eco-friendly modes and features, including everything down to the sustainability of the thermostat's packaging. Thermostats with eco-modes and indicators on the display score better than those without them, as do systems with reporting features such as emails or in-app data that can lend insight into energy usage and help us develop habits to improve efficiency and best practices.

thermostat - we evaluated any energy-saving modes featured on each of the...
We evaluated any energy-saving modes featured on each of the thermostats we tested.
Credit: Matt Lighthart

Conclusion


We trust that this guide has shed light on our process of evaluating the wide array of thermostats available on the market to identify the most promising options and the criteria behind selecting our award winners. For a deeper look at the side-by-side performance of these products, take a peek at our thermostat review, or check out our Buying Advice article for a detailed discussion of which type of thermostat is best for your needs and home.