Best answer: If you live in a multi-story home and own either a 3rd-gen Nest Learning Thermostat or a Thermostat E, the Nest Temperature Sensor is a good way to manage the comfort of your home.
Best Buy: Temperature Sensor ($40)
What does the Nest Temperature Sensor do?
The Nest Temperature Sensor is a small plastic puck that connects to your Nest thermostat over Bluetooth and, as the name implies, measures and reports the surrounding temperature. There's a small hole on the back that you can use to mount the sensor to the wall, or you can simply place it on a shelf or table — either way works just as well.
Once the Nest Temperature Sensor is set up, you can check the temperature of the room it's in from the Nest app, and adjust your thermostat accordingly. This is ideal for multi-story homes, where upstairs will usually be a few degrees warmer than the lower levels. You only need one thermostat for most houses, but adding sensors to each level — or to rooms that tend to run hot or cold — can allow your Nest system to better heat and cool your house to your liking.
If you tend to spend certain times of day in different parts of the house — say, you wake up and get ready upstairs in the mornings, then come downstairs for breakfast — you can also use the Nest Temperature Sensor to schedule your thermostat based around those habits. At least, this is the general idea, but Nest's lackluster scheduling limits the usefulness of this feature.
Within the Temperature Sensor management page of the Nest app, there are four time segments: morning (7AM to 11AM), midday (11AM to 4PM), evening (4PM to 9PM), and night (9PM to 7AM). You can choose which sensor to prioritize for each segment between the thermostat itself and any Temperature Sensors you have, but you can't customize how those segments are divided up, so it might not be ideal for all lifestyles.
What models will the Nest Temperature Sensor work with?
Nest's site lists that the Temperature Sensor is only compatible with the 3rd-gen Nest Learning Thermostat and the more affordable Nest Thermostat E. If you have an older model, the Temperature Sensor simply won't pair with it in the Nest app.
If you're unsure which Learning Thermostat you have, Nest has a quick guide that breaks down the differences in aesthetics, apps, and serial numbers, but if you bought your thermostat before late 2015, when the 3rd-gen Learning Thermostat was released, it's safe to say you've got an older model that won't work with the Temperature Sensor.
A simple, but limited way to monitor and adjust the temperature in different parts of your home.
Despite an inflexible scheduling system, the Nest Temperature Sensor is a relatively inexpensive way to keep track of the difference in temperature throughout your home. Especially if you live in a multi-story house, it can keep you from freezing when you go downstairs in the mornings.
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Hayato was a product reviewer and video editor for Android Central.