Editor’s note: Originally published December 2020. Reviewed and updated November 2026. Some models mentioned here may have been updated or discontinued since; check current availability and specifications before buying.
The ecobee3 is a Wi-Fi smart thermostat built around one standout idea: wireless remote sensors that detect temperature and motion in other rooms, so the system can heat or cool based on where people actually are. This review covers how it works, its modes, compatibility, listed specifications and installation, based on manufacturer information, to help you decide if it fits your home.
Quick answer
- The ecobee3’s key feature is its remote sensors, which detect temperature and motion room by room; up to 32 can be connected.
- It works with conventional gas, oil, electric and dual-fuel systems (2H/2C) and heat pumps (4H/2C), plus accessories such as humidifiers and ventilators.
- A Power Extender Kit is included for homes without a C wire, though fitting it may need some electrical know-how.
- It works with Alexa, Apple HomeKit, SmartThings, IFTTT and other platforms, and is controlled from iOS and Android apps.
- The ecobee3 lite drops accessory support; the ecobee4 adds built-in Alexa.
ecobee3 vs ecobee3 lite vs ecobee4
Ecobee, Nest and Honeywell were the three main names in smart thermostats when this review was written, and each has its own strengths, so it’s worth comparing before you buy. Our ecobee vs Nest comparison covers the biggest rival.
Within ecobee’s own range at the time, the main difference between the ecobee3 and the ecobee3 lite was that the lite version doesn’t support accessories such as humidifiers, dehumidifiers and ventilators. The ecobee4 added Amazon Alexa built in.
Remote sensors
The remote sensors are what set the ecobee3 apart. Sold in two-packs, they detect temperature and motion, letting the thermostat account for each room that has a sensor rather than just the hallway where the thermostat hangs. The manufacturer says most small pets won’t set off the motion sensors.
DataRhythm learning technology
Ecobee’s built-in DataRhythm software is designed to learn your home without manual programming. According to ecobee, it analyzes factors such as outdoor temperatures, your sensor settings and your home’s energy profile to find the most efficient way to keep you comfortable.
Smart modes and options
- Follow Me: turns sensors on and off as you move from room to room.
- Sleep: turns off sensors in specified rooms overnight to save energy.
- Home: turns all sensors on to your programmed temperatures.
- Away: maximizes savings while you’re out for a set time.
- Scheduling: set home and away periods around your routine.
- Home IQ: monthly statistics and energy-saving tips, like a simple energy audit.
Features and settings
- Up/down slide control on the touchscreen for temperature adjustments.
- Alerts when issues are detected and reminders for regular maintenance.
- Touchscreen shows time, date, temperature, humidity and live weather.
- Remote control from iOS and Android phones, tablets and computers.
- Three-year limited manufacturer’s warranty (at the time of writing).
Works with
- Amazon Echo (Alexa)
- Apple Watch
- Apple HomeKit (Siri)
- IFTTT
- Samsung SmartThings
- Wink
Listed specifications
Thermostat
- 3.93-inch rounded square unit, 0.86 inch deep
- 3.5-inch full-color LCD touchscreen, 320 x 480 pixels
- Works with conventional electric, oil, gas and dual-fuel systems (2H/2C)
- Compatible with heat pumps (4H/2C), humidifiers, dehumidifiers and ventilators
- Senses temperature, motion and humidity around the unit
- Temperature set range: 45°F to 92°F
- Hardwired for continuous operation
- Includes large and small trim plates
- Supports up to 32 wireless sensors
- Includes a Power Extender Kit for systems without a C wire
- Bandwidth use of about 15 to 20 MB per month
- Built-in Wi-Fi, lockable, backlit display
- Mercury-, arsenic- and PVC-free, RoHS compliant, recyclable packaging
Remote sensor
- 1.7-inch rounded square (2.12 inches with stand), 0.78 inch deep
- Uses a CR2032 coin-cell battery
- Senses temperature and motion
- Operating range of about 45 feet
Installation
If your system has a C wire, ecobee says installation should take less than 45 minutes, guided by a setup wizard and quick start guide in the app. Ecobee also offers a professional installation service.
Older wiring often lacks a C wire, which makes the job more complicated. The included Power Extender Kit (PEK) avoids running a new wire, but it is installed at the HVAC control board. If you’re comfortable with basic electrical work you can do it yourself; otherwise, hire an electrician or HVAC technician. Not sure what your system needs? Our thermostat buying guide explains compatibility.
Pros and cons
Pros
- Remote sensors give room-by-room awareness and respond to occupancy
- DataRhythm learning is designed to optimize savings without manual programming
- Works with Alexa, Siri/HomeKit, SmartThings and most Android and iOS devices
- Power Extender Kit included for homes without a C wire
- Energy Star certified
Cons
- The slide control can be over-sensitive for small adjustments
- The unit and sensors feel less premium than some competitors
- It cannot redirect warm or cool air between rooms; it can only decide when to run the system
- Fitting the Power Extender Kit may require an electrician
Bottom line
The ecobee3 is worth considering if uneven temperatures between rooms are your main complaint, since its remote sensors let the thermostat respond to the rooms you’re actually using. It works with most residential heating and cooling systems and includes a workaround for homes without a C wire. Practical uses include keeping a nursery at a steady temperature or letting a guest room’s sensor count only when someone is in it.
If built-in Alexa matters to you, read our ecobee4 review; to see other brands, browse our Nest thermostat reviews.
FAQ
Does the ecobee3 need a C wire?
It is hardwired, but it includes a Power Extender Kit so you can install it without running a C wire on older systems.
How many remote sensors can the ecobee3 use?
Up to 32 wireless sensors can be connected at the same time, according to the manufacturer.
What’s the difference between the ecobee3 and ecobee3 lite?
The lite version doesn’t support accessories such as humidifiers, dehumidifiers and ventilators.
