Traditional, non-smart thermostats act as a switch that turn your heat or air-conditioning on or off. It doesn’t need a steady power source. Today’s connected thermostats, on the other hand, need electricity to power the unit’s backlit display and other functions and features.
A C-wire, put simply, supplies constant power to your connected thermostat. If you want a smart thermostat but do not have a C-wire to power it, then you can run a new thermostat wire from your thermostat to your furnace.
However, this can take a lot of work, depending on the distance between the two. If you don’t want that, you can buy an adapter that allows you to add a C-wire to your thermostat. This option, however, is only ideal for those smart thermostats that already have a four-wire 24VAC layout and lack only a C-wire.
Plus, installation can be a tad too daunting, especially for people who do not know how to open their furnaces.
You can also just simply buy a smart thermostat that does not need a C-wire. You still get the same features as other smart thermostats without the need to trouble yourself with costly and complex installation.
These are the three best Wi-Fi thermostats in the market that do not need a C-wire:
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#1 Nest Learning Thermostat
- Smart Learning: The Nest Learning Thermostat takes away the hassle of having to program everything. It learns your behavior automatically to give you the perfect levels of cooling and heating while also allowing you to save on your fuel costs.
- Starts Working Quickly: It takes only a week for Nest to know about your routines, and then it pretty much works on its own after. The thermostat uses your phone’s GPS and sensors to know whether somebody’s home or not, and if everybody’s out, it will turn on Eco Temperature mode to save energy. Note: learn more about how it works.
- Farsight Tech: With its Farsight feature, Nest lights up when you go inside the room to show you the current temperature, time or weather.
- App Control: It has a companion app that allows you to see how much energy you have used, how much you have saved, and how to save more on energy. This app also allows you to control the thermostat using your smartphone.
- Design: Nest is beautifully designed. From its interface to its steel ring, Nest harmoniously blends with your wall no matter color it is. However, the Nest’s real value is in its sensors. Ambient light sensors can adjust the brightness of the display, while it tracks the last 10 temperatures of your home. It also has a humidity sensor to show you how muggy it is inside your home and even turn on the dehumidifier to help things a bit. Nest also checks the weather report so that it could adjust the temperature inside your house based on whether it is hot or cold outside.
Even while the Nest Learning Thermostat does not really need a C-wire, there are instances when it is recommended. Nest recharges its batteries using the heating and cooling wires, and it “steals” power from these wires to operate. But if you are using Nest with some control panels that will require a C-wire, then you need one. Some micro-controller-based systems and some gas valves also need a C-wire to work with Nest.
#2 Ecobee
- One of the Smartest Thermostats: One of the biggest advantages of getting an Ecobee3 is that it works even without a C-wire. Ecobee was the first company to come out with a thermostat that is app-enabled. Now on its third generation, Ecobee gives you a Wi-Fi thermostat and a remote temperature sensor that can be integrated with IFTTT, Apple Homekit and Amazon Alexa. NOTE: I’ve now updated this section for the release of the new Ecobee4 (read more about it here).
- Offers a Solid C-Wire Workaround: Ecobee technically needs a C-wire, but if your current heating and cooling systems do not have it, you can use the Power Extender Kit that is included in the package.
- Multiple Room Sensors: Ecobee has room sensors that allow it to detect cold or hot areas in the room and adjust the temperature accordingly. You can also use your smartphone to adjust the temperature. The Ecobee can detect if there is somebody in the room or not and it can connect to and control other devices. The companion app gives you monthly reports on your saved energy and gives you tips on how to save more energy. On the average, you could cut 23% on your energy costs.
- Does Not Steal Power: Unlike the Nest Learning Thermometer, Ecobee does not steal power from other wires in your thermostat unit to charge.
- Better Integrations: The IFTTT integration is one feature to watch. It certainly is very useful if you have a connected home, and it allows you to get more out of your smart thermostat. For instance, you can get an IFTTT recipe that would notify you when your Ecobee goes on Away mode automatically. You can also use Ecobee with your Amazon Alexa, allowing you to speak to it in order to adjust the temperature.
#3 Sensi Wi-Fi Thermostat
The Emerson Sensi Wi-Fi Thermostat promises to give you everything you need in a thermostat, allowing you to feel utmost comfort in your home. It boasts easy installation, one you can do yourself. It also boasts a companion app that enables you to remotely adjust heat and cooling from anywhere in the world.
The mobile app gives you the current temperature in your home, as well as humidity levels and even the current weather forecast. It also allows you to see your upcoming cooling and heating schedules.
- A Good Halfway Point: Sensi looks like your typical current thermostats, which means that even if you have a traditional-looking home, the device will still fit right in. Even so, it has modern features that you would look for in a thermostat.
- Flexibility: For instance, it displays the current temperature and humidity, and it can show you the weather report for the day. It also allows you to manually schedule your heating and cooling preferences, and you can use it with Amazon Alexa as well as the Wink Hub.
- Simple Installation: Sensi Wi-Fi Thermostat is very simple to install and very simple to set up. It also has a backlight button that is always lit to make it easier for you to see things even in the dark.
Comparing the Top Battery Operated WiFi Thermostats Without C-Wire
While it seems that Ecobee3 and Nest Learning Thermostat are keen on competing with each other as far as price is concerned, Sensi Wi-Fi Thermostat is happy to give users a more affordable choice. The Ecobee4 and Nest are each priced comparably, while the Sensi is the cheapest here.
Despite being cheaper, Sensi offers most of the basic features you’d find in the more expensive brands. For instance, all three display temperatures on screen, as well as humidity and time. You can also get weather reports for the day. All three allow you to control the fans while also having a companion app that enables you to control the heat and cooling at home from anywhere in the world. All three also offer some way to manually schedule heating and cooling for your home, as well as offer the ability to lock the thermostat so that your kids and other people would not be able to adjust it.
That cheaper price tag, however, does come with some trade-offs. For one, your Sensi Wi-Fi Thermostat does not have sensors that allow it to detect if there is a person in the room and its mobile app does not have usage logs. These are features that both Nest and Ecobee3 offer.
One of the most pronounced differences between the three thermostats is the way you control the thermostat unit when you do not have your phone with you. Sensi Wi-Fi Thermostat is controlled by physical buttons on the unit, while Nest 3rd Generation has a rotary knob around the main unit. Only Ecobee3 gives you a touchscreen interface to make adjusting temperatures a whole lot easier.
Ecobee3 also has remote sensors that help you get the most comfortable temperatures in different areas of the house. However, while Ecobee3 has a simple workaround to the C-wire problem, it might not be that simple to install. You need to put the extender directly on your HVAC unit’s controller board. So it might not be easy to do for a beginner.
Side by side comparison: Nest vs Ecobee vs Sensi Wi-Fi
This table provides an easier look at the features for each thermostat:
| Nest 3rd Generation | Ecobee 4 | Sensi Wi-Fi | |
| Manufacturer’s Price | Check here for latest | Check here for latest | Check here for latest |
| Dimensions (HWD, inches) | 3.3 x 3.3 x 1.2 | 3.9 x 3.9 x 0.9 | 5.9 x 3.8 x 1.1 |
| Touch Screen | No | Yes | Yes |
| Remote Control | Yes | Yes | Yes |
| Temperature Display | Yes | Yes | Yes |
| Humidity display | Yes | Yes | Yes |
| Time Display | Yes | Yes | Yes |
| Fan control | Yes | Yes | Yes |
| Remote Sensors | No | Yes | No |
| Human Activity Sensor | Yes | Yes | No |
| Smart Response or autoscheduling | Yes | Yes | No |
| Manual scheduling | Yes | Yes | Yes |
| Energy History | Yes | Yes | No |
| Weather Conditions | Yes | Yes | Yes |
| Lock Feature | Yes | Yes | Yes |
| Battery required | Yes | Yes | Yes |
| Color | Stainless steel, white, copper, black | Black and white | White |
Looking for a Honeywell Thermostat With No C Wire?
I’ve received this question a few times, so I wanted to answer it in context here.
While the latest “smart” Thermostats from Honeywell (Lyric models) typically do require C-wires off the shelf, you can opt for a capable their 7-Day WiFi Programmable Thermostat here instead. It’s not specifically “smart learning” like the Nest, Lyric, Ecobee, etc… but the WiFi customization makes it significantly smarter than “most” thermostats.
Final say: What should you buy?
If you only need a thermostat that would allow you to easily control your house’s temperature without the frills, then you should consider the Sensi Wi-Fi Thermostat. This allows you to save more than $100 while giving you a decent set of features, including integration with Amazon Alexa and Wink.
If Price is the Issue: Sensi Wi-Fi Thermostat is also a good choice for people who do not want to tinker with their HVAC systems too much just to solve the no C-wire problem.
For Everyone Else: However, if you are looking for a smart thermostat that helps you save energy and cut costs, then check out the Ecobee4 and the Nest Learning Thermostat. These two might be worth the additional money you pay for them when you realize that they will keep you from heating or cooling a room when nobody is there. They also give you insights into your usage and even give you actionable tips to help you save even more.
Thermostat on the Way? Check out my guide to the optimal placement for WiFi thermostats or The Best Wifi Thermostats for your Vacation Home
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