Many high-end smart thermostats require a C-wire (regular wire) to provide adequate power for LED displays, Wi-Fi, and other advanced features. However, older homes often do not have a C-wire. As a result, many homeowners are looking for smart thermostats that don't require a C-wire.
The thermostats listed below operate with low power consumption or come with easy-to-install, DIY power supplies. If you are familiar with smart thermostats, you will notice that the listed thermostats are the best-selling and most well-known thermostats.
Manufacturers have found ways to make their products accessible to everyone.
The choices below are our favorites that can help you get around the need to own the home you need. However, note that performance without a C-wire may vary depending on the thermostat. Nest is notorious for internal battery drain issues.
Ecobee Premium Smart Thermostat
Ecobee children's and biggest thermostat!
Use Power Extender Kit (PEK)
If you don't have a C-wire, and at least four wires are available on the thermostat, you can use the Power Extender Kit (PEK). The PEK is installed on the furnace control panel and is connected to the existing thermostat wires to generate wire C. Installation is usually very simple and straightforward.
Ecobee's latest smart thermostat improves on the features that made previous models unique - it now supports up to 32 room sensors, has a stunning new larger display and uses radar to detect presence.
What makes it stand out? The thermostat includes built-in Alexa and Siri voice controls, along with high-quality microphones and a speaker, allowing you to easily adjust the temperature with simple voice commands. In addition, the thermostat is equipped with an integrated air quality sensor that ensures that you are breathing clean air.
Ecobee 3 Lite
The cheapest Ecobee thermostat
Use Power Extender Kit (PEK)
The Ecobee 3 lite lacks some of the practical features found in the Premium model, such as an integrated presence sensor and built-in voice control.
However, it's a great, affordable choice, allowing you to remotely control your home's heating and cooling via apps or smart home assistant devices.
Additionally, the ecobee3 lite includes a power extension kit to bypass the need for a C-cable.
The Ecobee 3 Lite is what I personally use in my home and it meets my needs perfectly.
Google Nest thermostat
The cheapest Google Nest thermostat
Use Powersteal
The latest Nest thermostat can work without a C-wire; however, some customers ended up having to plug it in.
The need for the C wire depends on whether the R and Y wires provide enough voltage to power all functions; if not, the Nest Thermostat will disable some functions to keep the indoor temperature under control or will display errors that are difficult to troubleshoot.
If your HVAC system is fully compliant, a thermostat is a versatile and cost-effective device that uses geofencing and motion tracking to identify you when you're not home, potentially saving you a significant amount of money.
If you're experiencing problems, consider installing a new Nest power connector to see if that fixes the problem.
Google Nest learning thermostat
Children's and the largest Google Nest thermostat!
Use Powersteal
The Nest Learning Thermostat continues to be one of the smartest and most versatile thermostats available, offering multi-zone support, customizable scheduling, Alexa/Google Assistant integration, and HVAC monitoring.
The Nest Learning Thermostat uses energy theft just like the previous Nest Thermostat.
However, installing without a C-wire can lead to problems with power cycles, among other things.
Google introduced the Nest Power Connector as an alternative to the C-cable for constant power, but it may not be suitable for all homes.
It's worth trying Nest Thermostats without the C-wire, but save the receipt just in case.
Nest Power Port - Nest Thermostat C Cable Adapter
For Nest thermostat power issues that limit its capabilities, this power connector serves as a C-wire replacement. Google's how-to video shows you how to install it, or you can pay for a professional installation.
Amazon Smart Thermostat
Use Power Extender Kit (PEK)
If your system does not have a C-wire, the Amazon Smart Thermostat can be purchased with a C-wire power supply that can be used as an alternative to provide the necessary power to the thermostat. The C-wire power supply is the so-called version of the power supply extension kit.
The Amazon Smart Thermostat is an affordable and easy-to-use smart thermostat designed to help you efficiently manage your home's heating and cooling. It's compatible with popular voice assistants like Amazon Alexa, allowing you to control your thermostat with voice commands.
With features such as scheduling, energy-saving modes and remote control via the Alexa app, it aims to simplify climate control and reduce energy consumption. The easy installation process and compatibility with most HVAC systems make it an attractive option for homeowners looking for an affordable smart thermostat with basic features.
Mysa smart thermostat
For high voltage HVAC systems (120V - 240V).
In the rare case that the smart thermostat is compatible with 120V-240V, electric panels and fan heaters, you can usually install the Mysa smart thermostat yourself in just a few minutes.
Compatible with Alexa, Google and HomeKit, it offers all the smart features needed to reduce energy consumption, such as app scheduling, geofencing to detect when you're away from home, pre-heating or pre-cooling depending on your routine and comprehensive energy reports for potential upgrades .
Lux Kono
Use Power Extender Kit (PEK)
If you don't have a C wire, and at least four wires are available on the thermostat, you can use the LUX Power Bridge. The Power Bridge is the so-called version of the Power Extender Kit (PEK).
The LUX Power Bridge is installed on the furnace control panel and is connected to the existing thermostat wires to generate wire C. Installation is usually very easy and simple.
Lux Kono is an elegant and stylish smart thermostat that offers a range of features to help you efficiently manage heating and cooling in your home. It is compatible with popular smart home systems such as Amazon Alexa, Google Assistant and Apple HomeKit, allowing you to control the thermostat with voice commands.
Lux Kono also supports geofencing and offers energy-saving scheduling options to reduce energy consumption. The user-friendly interface and easy installation make it an attractive choice for homeowners looking for an affordable smart thermostat with basic features.
I personally prefer the Ecobee interface to the Lux, but I know not everyone will like it as much as I do.
Sensibo Sky - an intelligent home air conditioning system
Smart air conditioning - it doesn't have to be central
Aside from the C duct problem, some people may not have central air conditioning but still want to regulate the climate in their home.
In these cases, Sensibo Sky can control mini-split or portable air conditioners, allowing you to set heating or cooling schedules or select precise temperatures via Wi-Fi monitoring.
In addition, it allows you to control air conditioners using Amazon Echo or Google Home voice commands, increasing convenience and ease of use.
Abstract
From personal experience with friends, family and my own home, I recommend buying a nest or Ecobee.
Nest thermostats can work in some homes without a C-wire, but there is still the possibility that additional power will be required.
Google introduced a new Google Nest power connector to bypass the C-cable requirement, which solved some users' issues.
However, other reviewers mentioned that their low power issues persisted even with the new power port. As such, the performance of the Nest Thermostat without C-Wire may vary from home to home.
For those with some electrical know-how (and a little extra math), the Ecobee Smart Thermostat Premium requires a power extension kit to be wired to replace the missing C wire.
Fortunately, Ecobee designed the kit with self-assembly in mind, making the process relatively simple. Once installed, it becomes the ultimate multi-zone smart thermostat, making it ideal for large homes with unevenly heated rooms.
From multi-room sensor integration to built-in Alexa to control your entire home, the Ecobee thermostat is truly the pinnacle of smart thermostats — and its price reflects that.