The 8 Best Smart Thermostats Without a C Wire

Imagine forgetting to turn on your AC in July and you’re away on vacation.  

With the introduction of smart thermostats, you no longer need to worry about calling the neighbor to come over and check your house isn’t burning up on the inside.

However, most of these modern thermostats require a c-wire or a common wire that allows for constant power through your low-voltage heating system.

If you’re looking to replace your current thermostat with a smarter one that operates completely without a c-wire or blue wire, then your best choice is the Google Nest Thermostat E or Nest Third Generation.

The best overall smart thermostat is the Ecobee Smart Thermostat, but it does need a c-wire adapter.

But, you will find that this system is so feature-rich and easy to use that it’s worth the effort of using an adapter.

We’ll look at what makes Ecobee thermostats the best all-around, discuss what you need to know about your home’s thermostat wires, and cover the top eight smart thermostats without c wires in other categories.

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At a Glance: Our Top Picks
Smart Thermostat

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WYZE Smart 

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Why do Smart Thermostats Need a C-Wire?

Smart thermostats need a strong power source because they’re in charge of your HVAC system or heat pumps while needing a wi-fi connection.

A wi-fi thermostat offers the convenience of adjusting your home’s temperature by using your phone, tablet, smart speaker, or other wifi-connected device and is considered highly efficient while lowering your energy bill.

So, batteries don’t provide enough of a power supply and power stealing can work, but it’s unreliable. A c-wire or common wire is the answer as it charges your smart thermostat as long as you have power in your home.  

More specifically, the c-wire enables the flow of 24 VAC consistent power to the thermostat. What happens is the r-wire or red wire needs the common wire to complete the circuit of electricity.

Unfortunately, not every home runs on low-voltage electricity and it makes installing these newer systems confusing and challenging.

If you had an old thermostat, you did not need this type of continuous power because they were simpler devices that you would turn on and off. 

Considering the luxurious features of newer models, including digital displays and voice activation, smart thermostats need a steady supply of electricity.

Power extenders or power adapters are excellent alternatives if you want to bypass the c-wire requirement or find that your HVAC system doesn’t use the c-wire.

You Can Use A G-Wire

A g-wire or a fan wire can frequently be used as a common wire.

You will have to do some simple wiring inside your HVAC system and at your smart thermostat outlet to replace it as a terminal. However, you will lose your fan control if you do this.

Also, if you notice an extra unused wire in the wall, that can work as a blue or common wire for your new smart thermostat.

The extra wire will also need to be connected to the c terminal at the heating and cooling system. This will provide power to your new thermostat.

Here are eight of the Best Smart Thermostats Without C-Wire

1. Best Overall Smart Thermostat

Ecobee Smart
Ecobee Smart

Ecobee Smart Thermostat with Voice Control– C-Wire Adapter

Perhaps the Queen of all popular smart thermostats at this time.  

You won’t have many complaints with this “master of all features.” The Ecobee is a feature-rich model that works with almost any HVAC system installation.

 It has a sharp, minimalist design that adds to your “wall swag.”

Some of Ecobee’s basic features include auto-learning your household’s temperature preferences. This function means it will control your climate system without you having to lift a finger.

You also get a built-in smart assistant in Siri and Alexa. So, you can play your favorite music, and take calls.

  • Major money saver. The makers say the Ecobee saves you 26percent yearly on heating and cooling costs.
  • Auto Home/auto-away function.
  • SmartSensor technology means the unoccupied rooms, don’t get heat.
  • Compatible with most 24 VAC HVAC equipment, including most furnaces and air conditioners. The Power Extender Kit enables DIY installation without a C-wire.
  • You are paying for the intelligence here.  It’s more expensive than most systems in its category.
  • The built-in voice-activated feature can interfere with your current smart assistant, like Alexa.
  • Wiring configuration may still be a bit confusing for home DIYers. Some complain that the paper manual is incorrect.

2. Best Affordable Smart Thermostat

WYZE Smart
WYZE Smart 

Wyze Smart WiFi Thermostat  – C-Wire adapter

This is one of the least expensive thermostats on the market but has many of the same features you’re going to get with the more expensive devices.

Its design is simple and sleek. And you won’t fuss with the rotating dial and easy-to-use interface.

Some of the Wyze basic features include programming for home, away, and sleep modes. Control temperature inside from anywhere using a wifi-connected device.

It works with voice assistants like Alexa and allows you to schedule your household temp for a week in advance.  

  • Half the cost of the other smart thermostats with most of the same features.
  • Consistent heating and cooling functions with the c-wire adapter.
  • Simple design with minimal physical settings.
  • Easy installation. About 20 or 30 mins to fully set up.
  • Few setting options on the physical thermostat. Most of the computing is in the Cloud.
  • Need a c-wire adapter. This means you have to go down to your HVAC system and install the adapter inside.
  • Can experience dropped connection. Wi-Fi connectivity is intermittent.

3. Best TouchScreen Smart Thermostat

Emerson Sensi
Emerson Sensi

Emerson Sensi Wifi Smart Thermostat – needs a power extender

If you’re looking for a well-rounded smart thermostat without a high price tag, this is an excellent choice. This smart cookie has a satisfying touchscreen display. It’s modern and easy to use.  

There’s an automatic dimming feature when it’s not in use as well as a soft nightlight mode. It also looks great on your wall with slick white contours.

Some of Emerson Sensi’s basic features include Seamless integration with your home’s smart systems including Alexa, Google Assistant, Apple HomeKit, and Wink. It also, has smart alerts, scheduling functions, and usage reports.

  • Energy-efficient and cost-effective. Manufacturers say you can save 23% on HVAC energy.
  • Alexa voice compatibility.
  • Easy-peasy DIY install within half an hour. Clear and concise app instructions.
  • Simple controls and large text displays make programming effortless.
  • Complaints of unreliability. WiFi connection interruptions.
  • Randomly changes temps even when not on schedule mode.
  • Customer service can be slow to respond.

4. Best Alexa Compatible Smart Thermostat

Google Nest
Google Nest

Google Nest Thermostat E–  NoC-Wire.

If you don’t want to give up your relationship with Alexa, you won’t have to with the Google Nest smart thermostat.

This economical device is designed to meld with your Alexa system seamlessly, so you can tell her to cool the room or make it toasty.

The stainless steel sleek design looks like art on the wall and offers you remote control of your HVAC system from your tablet, phone, or laptop.

Some of Google Nest’s basic features include Home/Away Assist which adjusts itself to an efficient temperature when you leave the house or are away on vacation.  

Also, it’s programmable through the Google Home app on your Android or iPhone which includes a scheduling function for energy efficiency.

  • Easy programming. Dial up or down.
  • The app is user-friendly.
  • The scheduling function through the app enables you to control it from anywhere
  • Budget-friendly.
  • Product descriptions lacking.
  • Doesn’t work with all HVAC systems.
  • Customer service sometimes lacking.

5. Best High-End Luxury Smart Thermostat

Google Nest Learning
Google Nest Learning

Google Nest Learning Thermostat– no c-wire 

Here’s Google’s third-generation smart offering that learns what you like, so you don’t have to fiddle with programming.  

This smart thermostat is pretty to look at and it’s also easy to handle. You just turn it up or down and it remembers the temperatures you like when you’re home.

Other Google Nest Learning basic features include:  Intuitively learns your schedule, then programs itself, helping you save energy and costs.

With the Nest App, you can adjust the temperature at home from anywhere on almost any device. Also has heating and cooling system alerts that notify you of potential problems with HVAC systems.

  • The Farsight feature will sense your movement from far away and shows you different displays as you approach.
  • Nest temperature sensors allow you to adjust the temp according to a specific room.
  • The scheduling program makes it easy to set temps on the go. Also turns itself down when you’re away from home.
  • Learning functionality means it learns your preferences and automatically adjusts to the way you use the thermostat.
  • The learning aspect of the device means you don’t have as much control.
  • Complaints that thermostat is difficult to set up and c-wire still necessary.
  • Large temperature swings. This means rooms can get too cold before the thermostat kicks into gear.

6. Best Baseboard Heater Smart Thermostat

Mysa Smart
Mysa Smart

Mysa Smart Thermostat – Electric Corded

The Mysa Smart Thermostat has a mission: to control the temperature of your baseboard heater.

But, its stylish mission won’t get in the way of Alexa’s operation to serve you, so you get voice activation as a bonus.

This system works with high-voltage electric baseboards and electric fan-forced heaters with a clean, modern interface.

Mysa basic features include easy integration with other smart technology like Alexa and Google Assistant. You can use the app to control your home’s heating and the display is super simple and easy to set.

  • Alexa compatible.
  • Adaptive Display Technology lights up when you’re approaching.
  • Use your phone or tablet to control your electric baseboard heaters.
  • Easy installation. Takes only about 15 minutes.
  • Must be turned off through the app.
  • High price with limited functionality.
  • The display is unpredictable and not ideal for the bedroom as the light can shine too bright.

7. Best Sensor Smart Thermostat

Ecobee3 Lite
Ecobee3 Lite

Ecobee3 lite  – Power Extender Needed

This is another knockout from Ecobee. With its modern room sensor, you’ll be able to change the temperature in your house based on specific areas or rooms.

The cool minimalist display looks great on any wall and can show you what the weather forecast looks like for the entire week.

Ecobee3 Lite’s basic features include Alexa compatibility, so it can adjust the HVAC with your voice.  Simple and responsive touchscreen that lights up when you’re nearby.

The room sensor helps balance temps throughout your house or you can set a room to a particular temperature. You also get home usage reports showing how you use your HVAC.

  • Room sensor allows you to have control over how you would like specific rooms to be heated or cooled.
  • Easy installation with excellent customer service.
  • Compatible with Alexa, Google, and HomeKit voice assistants.
  • Responsive touchscreen.
  • Numbers on the display are inconsistent – digits for temp adjustment are small and hard to see from far away.
  • A room sensor is an average temperature based on motion or occupancy in a room. Doesn’t let you set a precise set point, so that room may be cooler or warmer than you would like.
  • The proximity detector cannot be deactivated.

8. Best Air Conditioner Smart Thermostat

Sensibo Sky
Sensibo Sky

Sensibo Sky Smart Home Air Conditioner– Plug In

This is smart AC control at your service.

The Sensibo is a mobile system that can turn your existing air conditioner or your “mini-split / ductless / heat pump” system into a smart AC. 

It integrates with Alexa and other smart assistants and it’s chic-looking with a two-tone design.

The Sensibo Sky’s basic features include being Lightweight, so it can attach to any wall.

The app allows you to control fan speed, temperature, and humidity as well as when they should shut off or turn on.

You can also add more units to the app if you decide you need AC in different rooms.

  • Reduce energy bills by 40 percent by regulating your air conditioner from anywhere.
  • Easy setup. Barely need to read the instructions.
  • Integration with your other voice-activated home systems including Amazon Alexa, Google Assistant, Nest, Siri, and others.
  • Scheduling mode allows you to set your home’s air conditioning for a week in advance.
  • The scheduling function is not reliable. Problems were due to Sensibo’s infrared transmitter.
  • The USB cable provided is short. Limits where the device can be placed.
  • Limited functionality.

Wrap Up

So, the best choice overall is the Ecobee Smart Thermostat with Voice Control.

It has an abundance of smart features and allows you the freedom of setting up your winter cabin’s heating schedule before you even arrive. 

You also get a c-wire adapter with it, so you don’t have to worry about any additional wiring for your HVAC.

For those who don’t even want to fuss with an adapter or power extender, there are Google’s popular options including the Google Nest E and the Nest Third Generation.

Both are stylish leaders in delivering smart heating and cooling through your phone, tablet, or laptop

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