Smart Thermostats
Schedules, remote sensors and the honest version of "saves you money".
A smart thermostat is the rare smart home device with a plausible financial argument. It also has the most prerequisites of anything you will buy, which is why so many end up in a drawer.
Before you compare features, spend five minutes with your existing thermostat: photograph the wiring, note the system type, and check whether there is a C wire. That photo decides your shortlist more than any review.
Check compatibility before you compare features
- C wire: the common wire provides steady power. Without one, most smart thermostats need a power adapter kit, and some systems cannot supply enough power at all.
- System type: single-stage, multi-stage, heat pump, dual fuel, and zoned systems all have different requirements. Heat pumps in particular need explicit support — getting this wrong can cost real money.
- Line voltage: electric baseboard and in-floor heating use line voltage and need a completely different product. A standard low-voltage thermostat will not work, and installing one incorrectly is a fire risk.
Every major manufacturer publishes a compatibility checker. Use it, and keep the photo of your wiring.
What actually saves money
The savings come from schedule discipline, not machine learning. A thermostat that reliably sets back the temperature while you are at work and asleep will beat a "learning" thermostat you keep overriding.
Remote sensors matter more than most people expect. If your thermostat sits in a hallway that is always three degrees warmer than the bedroom, your system is conditioning the hallway. Sensors let the thermostat average or prioritize the rooms you are actually in — which improves comfort, and comfort is what makes people keep using the schedule.
Be skeptical of specific percentage savings claims. Real savings depend on your climate, your home's insulation, your utility rates and your habits. Your utility company's own data is more useful than any product page.
The hidden benefit: a thermostat is often a hub
Several popular smart thermostats include a voice assistant, a Zigbee or Thread radio, or both. In a hallway or living room position, that turns the thermostat into a cheap way to extend your smart home network and add a voice control point where people actually walk past it. It is a real reason to pick one model over another.
Products mentioned in this guide
Products referenced in this guide, shown with the manufacturer's own photography. We do not publish prices or star ratings — both change faster than any article can be kept accurate.
Smart Thermostats
ecobee Smart Thermostat Premium
- Includes a remote SmartSensor for room-level temperature averaging
- Built-in voice assistant and a Zigbee radio for accessory devices
- Air quality monitoring and a glass-front touchscreen
Works with
- Apple Home
- Alexa
- Google Home
- SmartThings
Frequently asked questions
Will a smart thermostat save me money?
It can, mainly by keeping a setback schedule you would not maintain manually and by avoiding heating or cooling an empty house. The size of the saving depends on your climate, rates and current habits. Some utilities publish rebates for qualifying thermostats — check before you buy.
What if I do not have a C wire?
Most manufacturers sell or include a power adapter kit that borrows a wire from the existing bundle to supply constant power. If your system has fewer than four wires or you are unsure, check the manufacturer's compatibility tool or ask an HVAC technician before ordering.
Do smart thermostats work without Wi-Fi?
They keep running their schedule locally, so heating and cooling continue. You lose app control, remote access and weather-based adjustments until the connection returns.