Thermostats

The listing states that a C-wire is required. That is the single most useful sentence on any thermostat listing, because whether that conductor exists behind your current plate is not something anyone can tell you from here. The listing also states it works with Alexa and Ring. Check compatibility with the manufacturer tool before ordering, and cut power at the panel before removing anything.

Best forA household already on Alexa, after the manufacturer compatibility tool has been run.

The most equipped listing in the group: a smart sensor is stated as included, along with an air quality monitor and support for Alexa, Siri and Google Home. A remote sensor matters in houses where the hallway the thermostat lives in is not the room anyone sits in. Compatibility still has to be confirmed with the manufacturer tool, and power still comes off at the panel first.

Best forA house where the thermostat is in the wrong room and a remote sensor fixes it.

The listing states a Nest Temperature Sensor, 2nd gen, is included. That is the same idea as the ecobee remote sensor: read the temperature where people actually are rather than where the wiring happened to come out of the wall. Compatibility with your system is a question for the manufacturer tool, and the panel breaker comes off before the old unit does.

Best forA household on Google services replacing a thermostat in an awkward hallway.

The middle ecobee: the listing states Energy Star certification and support for Siri, Alexa and Google Assistant, without stating an included sensor or air quality monitor. Same three voice ecosystems as the Premium, fewer parts in the box. Run the manufacturer compatibility tool before ordering and cut power at the panel before the old plate comes off.

Best forA connected thermostat in the room people actually use, so no remote sensor is needed.

The listing states Wi-Fi, Alexa support, Energy Star certification, and DIY installation. Treat that last phrase as a description of the product category, not as permission — the manufacturer compatibility tool still decides whether it suits your system, the breaker still comes off at the panel first, and an uncertain job still belongs to a licensed HVAC professional.

Best forA straightforward connected replacement, once the compatibility tool has said yes.

The shortest listing in this category: a programmable Wi-Fi thermostat, and that is what it states. No sensor, no ecosystem list, no certification claim. Everything else — which systems it works with, whether the wiring behind your plate suits it — comes from the manufacturer compatibility tool rather than from anything printed here.

Best forA basic connected replacement where scheduling is all that is wanted.

The entry point in the ecobee line as listed: Energy Star certification and a programmable Wi-Fi thermostat, with no sensor, monitor, or voice ecosystem stated. It shares the manufacturer compatibility tool with the rest of the range, which is the only place the question of whether it suits your system gets answered.

Best forA scheduling upgrade where none of the sensor features would ever get used.

This listing does the thing the others mostly leave to a compatibility tool: it states what system the thermostat controls. Single-stage, 1 heat and 1 cool, with a 5-2 day schedule. If your system is not single-stage, that sentence has already answered the question. Turn the power off at the panel before any old thermostat comes off the wall, and check compatibility with the manufacturer tool before ordering.

Best forA single-stage system, confirmed with the manufacturer compatibility tool first.