4 Best Thermostats Without a C Wire (For 2024)

Last updated on April 12th, 2024

Do you want to buy a new thermostat but don’t have a C wire in your wiring system? That’s not a reason to worry. There are several models available in the market that work without a C wire. You’ll be surprised to know that several reputed brands sell thermostats without a C wire. To narrow down your search, we have compiled a list of thermostats without C wire that we liked.

The best thermostats without a C wire are:

  • Google Nest Thermostat
  • ecobee3 Lite Smart Thermostat
  • Sensibo Sky Thermostat
  • Emerson Sensi Wi-Fi Smart Thermostat

We are going to look at each of these thermostats in detail in this article so you can pick the best thermostat for you.

SpecsGoogle Nest Thermostatecobee3 Lite Smart ThermostatSensibo Sky Thermostat
TypeWi-Fi enabled programmableWi-Fi enabled programmableWi-Fi enabled automatic
Controller TypeTouchscreenTouchscreenApp
Special FeatureSends error alerts and maintenance remindersWindow and Door Sensor for temperature and humidityTurns any existing AC into a smart AC
Comparison between different thermostats without a C wire

Just in case you are wondering what’s all the hype about a C wire, let us tell that in brief.

What is a C wire?

C- Wire

The C wire provides a constant flow of power to the thermostat. Now, make one thing clear – C wire is not responsible for powering the thermostat. That task is done by the R wire.

The R wire provides 24 Volts of power but not constantly; it is alternating. The C wire keeps the power flowing in the circuit. It supplies low voltage to keep the advanced features like a touchscreen, Wi-Fi connection, etc., running in the thermostat.

The thing is, thermostats can, in fact, operate without a C wire if you provide them with an alternative source of low voltage. That’s why we use AA or AAA batteries in thermostats. These batteries provide the low voltage required and thus eliminate the need for a C wire.

So, in this article, all the thermostats we are going to discuss do not need a C wire. Let’s start discussing them one by one.

Google Nest Thermostat

Ratings: 4.2/5.0 (based on 13,082 reviews)

Product Dimensions: 4.8″D x 4.8″W x 1.9″H

Voltage: ‎24 Volts

Controller Type: Google Assistant, Amazon Alexa, Nest, iOS, Android

Why we selected this thermostat?

Google Nest Thermostat is a Wi-Fi-enabled device that you can control physically from the touchscreen. We adore the elegant mirrored display and the side touch bar that changes temperature with a simple swipe.

Remote control options include the Google Home app or integration with home assistants like Amazon Alexa and Google Assistant. If something doesn’t seem right, you immediately receive an alert on your mobile app.

Energy savings

Google Nest Thermostat is big on savings. It has an Energy Star certification, which means it consumes less power than traditional thermostats. It turns itself down when you leave the house and allows you to set an energy-efficient schedule. With the Savings Finder feature, you can look for more ways to save power.

Installation is simple and can be done under 30 minutes. It is compatible with 85% of heating and cooling systems. We really love that its plastic parts contain 49% recycled post-consumer plastic to reduce waste.

Pros and Cons


  • Energy Star certification
  • Uses 49% recycled plastic


  • Installation is difficult
  • Doesn’t sense outdoor humidity

ecobee3 Lite Smart Thermostat

Ratings: 4.6/5.0 (based on 11,434 reviews)

Product Dimensions: 1″D x 4.05″W x 4.05″H

Voltage: 24‎ Volts

Controller Type: Vera, Google Assistant, Amazon Alexa, iOS, Android

What’s great about this thermostat?

The ecobee3 Lite Smart Thermostat has won the Energy Star Partner of the Year award for 2023, which makes it one of the best thermostats without C wire in the year. It saves up to 23% per year on heating and cooling costs (compared to a hold of 72°F).

If you install Smart Sensors on doors and windows, the thermostat automatically turns down when a door/window is left open. It can be controlled from anywhere using the Eco+ app. It has an easy-to-use touchscreen panel from where you can access all the same settings as the app.

You can set a schedule, change temperature, see current weather conditions with indoor temperature and humidity, and a lot more. It even doubles down as a security base and keypad. You can integrate it into your entire security system and use the keypad to arm or disarm it.


Compatible with most 24 VAC HVAC systems:

  1. Furnaces
  2. ACs (2H/2C)
  3. Heat pumps (2H/2C + 2 stage AUX)
  4. Boilers
  5. PTACs
  6. Fan coil units (3 fan speeds)

Pros and Cons


  • Designed to save energy costs
  • Double downs as a security base


  • No built-in surge protection
  • Fewer savings as compared to other models

Sensibo Sky Thermostat

Ratings: 4.3/5.0 (based on 4,938 reviews)

Product Dimensions: 2.17″D x 3.23″W x 0.67″H

Voltage: ‎220 Volts

Controller Type: Google, Alexa, and Siri

What’s new in this thermostat?

The Sensibo Sky Thermostat is the world’s first intelligent AC and Heat Pump controller with indoor air quality monitoring. It even received the Time Magazine’s Top Best Innovation for 2023 award.

You can control any air conditioner and monitor indoor air quality at any point in time. The Climate React feature scans both indoor temperature and humidity to help you decide the ideal temperature for your home.

This leads to up to 40% reduction in your cooling bills. Plus, the geofencing compatibility contributes to the reduced costs. The thermostat detects when you leave the house, and it automatically turns down the cooling and turns it back up when you arrive in the vicinity of your home.

Other control options include the mobile app and voice commands when integrated with a home assistant. And did we tell you that this has 7-day full-week programming, just like Honeywell thermostats?


The Sensibo Sky Thermostat is compatible with

  1. Window AC
  2. Mini Split/Ductless ACs
  3. Heat pumps
  4. Portable ACs

Pros and Cons


  • Monitors indoor air quality
  • 7-day schedule programming


  • Complex installation process

Emerson Sensi Wi-Fi Smart Thermostat

Ratings: 4.5/5.0 (based on 19,864 reviews)

Product Dimensions: 1″D x 5.88″W x 3.75″H

Voltage: ‎24 Volts

Controller Type: Vera, Apple HomeKit, Google Assistant, Amazon Alexa, SmartThings

Why we included this thermostat in our list?

If you want a smart thermostat but don’t want the touchscreen because it smudges a lot, then the Emerson Sensi Wi-Fi Smart Thermostat will be a great choice. It has a 5-inch display panel with buttons to control the programs.

This, too, has Energy Star certification, just like the previous models. And be assured about your privacy because Emerson gives a privacy protection guarantee.

Remote control and monitoring

You have your Android and iOS compatible mobile app to receive alerts and notifications. The thermostat monitors the performance and efficiency of your HVAC system. It delivers valuable usage reports of your system, alerts about equipment malfunction, and maintenance reminders like filter replacement, etc., on your mobile app.


The Emerson Sensi thermostat is compatible with most conventional heating and cooling systems like:

  1. Gas furnace
  2. Electric furnace
  3. Air conditioner
  4. Boiler

Pros and Cons


  • Usage reports and alerts
  • Privacy protection guarantee


  • No humidity detection
  • No filter change reminder

Which of these should you buy?

We have given you our top 4 recommendations for the best thermostats without C wire, but still, you have to pick the final product. Your final choice should be based on the brand, price, features, and compatibility of the thermostat with your HVAC system.


This is the most important factor to consider. You need to ensure that the product you pick is compatible with your existing system. Otherwise, you will spend money only to discover you can install this thermostat in your system. We have included the compatibility of most thermostats above in our article. Do check that out before making the final decision.


Some of you might have loyalty towards a specific brand. We have seen users prefer Honeywell thermostats over others. If you like products from a certain brand or if you have previously owned a thermostat from that brand, then it would be a good idea to upgrade to a newer model from the same brand.


It’s human nature to look for value-for-money products. You must have an idea about how much you want to spend on a thermostat. So pick a product that fits into your price range. You don’t have to go above and beyond your price limit to get good thermostats without a C wire. There are several excellent budget options available.


Most modern thermostats have extra features besides heating and cooling. Some have sensors to know if any doors and windows are open and that’s causing temperature fluctuation while others have humidity detectors. Some models have a touchscreen and elegant designs. You have to decide which of these extra features you want to want.


Wiring for HVAC systems differs from model to model. Most of them have a C wire, so thermostats are designed to include a C wire attachment. However, some of the models do not have a C wire, and that’s when you need these thermostats without a C wire connection.

The products on our list of the best thermostats without a C wire are hand-picked and carefully studied by our research team. So you can be assured that they will work with your system. We have also included compatibility of most thermostats with different models so you can check whether your system is really compatible with the thermostat you buy.

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Siddhi Gurav

She is the editor and content writer at Smart Home Bulls. Siddhi merges her passion for language with SEO expertise. With 4 years of experience as a creative writer and a passion for smart home technology, she fits in perfectly at Smart Home Bulls. Her wide experience in content marketing has been an excellent addition to our team.

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