I Tested And Reviewed 8 Best Smart Thermostat No C Wire (2023)

I recently had the opportunity to try out the Ecobee4 thermostat, and I have to say, it was the perfect solution for my c wire issue. Not only was it affordable, but it was also incredibly easy to install.

The instructions provided with the Ecobee4 were clear and straightforward, and the company even offers phone support for any questions or concerns during the installation process. However, I did encounter a small hiccup along the way.

The instructions assumed that my AC unit had a circuit board, but unfortunately, mine did not. Instead, the thermostat wires were spliced onto the AC wires. Despite this setback, I was determined to find a solution.

After reaching out to Ecobee support and discussing the wiring schematic, we determined that the 24 volt wire should have been the brown wire. However, I noticed that it wasn't holding a constant charge, causing the thermostat to reboot whenever the air conditioning was turned on. Frustrated, I decided to revert everything back to its original state.

But then, I stumbled upon a power adapter on Amazon that seemed like the perfect solution. Since I had an electrical outlet right below my thermostat, I drilled a hole through the inside back of the outlet to run the cable through to the AC closet. From there, I ran the cable up and created another hole in the wall for the cable to go through to the thermostat.

After a bit of trial and error, I discovered that the negative cable should be connected to RC, while the positive cable goes to C. I have attached some pictures of my installation and how I wired my Ecobee thermostat, in the hopes that it can help others who may encounter a similar issue.

I want to express my gratitude to the team behind the transformer/adapter. It was exactly what I needed for my 3rd gen Nest thermostat. With only four wires (yellow, white, red, and green), I was missing the blue wire (C common wire) necessary to charge the Nest properly.

For two years, my Nest thermostat had been working fine, but recently, I started experiencing low battery issues and occasional system shutdowns with delayed error messages. Thankfully, the power adapter solved my problem.

To help others facing similar challenges, I connected one wire from the transformer to C and the second wire from the transformer to RC, along with the red wire. This setup worked perfectly for my heating and cooling system controlled by the Nest. I have included some pictures to provide visual guidance for anyone in a similar situation.

I hope my experience and instructions can be of assistance to those who are running heating and cooling systems through a Nest thermostat with only four wires. Remember, you don't need to use a jumper; simply connect your wires to RC and C, and you should be good to go.

The installation process for this product was quick and easy, taking less than 5 minutes. It involved unscrewing the mounting bracket from the wall and weaving the cord behind it, which was a simple task. I initially did a temporary installation by running the power cord under my door and connecting it to an inside outlet, but I plan to use the clips I purchased for a more permanent setup later. Despite the temporary arrangement, the product is working perfectly fine.

One of the main advantages of this product is that it eliminates the need to constantly charge the Ring doorbell. This is particularly beneficial during the winter when dealing with security screws in the cold would have been inconvenient. Additionally, the length of the cord is a definite plus. It can easily be trimmed down if it is too long, although it is unlikely that I will need to do so for my installation.

In my case, I had an old house that had not updated the boiler wiring to include three wires, including the C wire. However, I was able to overcome this issue by installing an outlet in the basement below the thermostat and fishing the cord up with the existing wires. It has been working well for the past few months.

Although the product does not come with instructions, the installation process is straightforward. All that is required is connecting one wire to the C terminal and the other to the RC plug, which provides power to your smart thermostat. Following these simple steps, the product functions exactly as described.

I am extremely satisfied with this transformer. It arrived promptly and was very easy to install. I have been using it to power my thermostat for several months now and have not encountered any issues.

I purchased a smart wifi thermostat to replace my older model that did not require a C wire. Unfortunately, I had the C wire but it was not connected to anything. As someone who is not an electrician, I was hesitant to connect the C wire incorrectly and risk damaging my furnace, air conditioning, or new thermostat. It was quite frustrating. That's when I came across this transformer as a safer alternative.

I read a review mentioning that this transformer caused someone's thermostat to burn out, which naturally made me concerned. However, upon further investigation, I realized that the person must have connected the wires incorrectly. To clarify, one wire should be placed in the R slot along with the red wire, and the other wire should be placed in the C slot. If you are unsure which wire is positive, I highly recommend using a voltage meter to check before installation. If the wires are marked, the wire with the stripe or dashed lines carries the positive end, while the unmarked wire carries the negative end. The positive wire should be connected to the C wire on the thermostat. It is crucial to do this correctly to avoid any potential fire hazards. It is important to note that any mishaps are not the fault of this product.

In my case, my house has AC/heat pump and my thermostat previously relied on batteries because my HVAC unit did not have a C wire. However, this transformer allowed me to connect the C and R pins (with the HVAC's Red line connected to R) and it worked flawlessly. It resolved the constant cycling on and off of the compressor that occurred when the Nest E thermostat was "power stealing" to keep itself charged.

I was tired of the basic thermostat in my apartment and wanted an upgrade. The installation process was straightforward with a 4-wire setup but no C wire. This transformer provided the perfect solution. After labeling and rewiring the new backplane, all I had to do was connect the C and Rc pins. I followed the installation instructions and removed the jumper between R and Rc as it was unnecessary with this external supply. Since I didn't want to drill any holes in the walls of my apartment, I simply ran the cable over the door frame and secured it with the provided staples. I then painted over it with some leftover paint to make it blend in seamlessly. I am very pleased with my new thermostat, and this external transformer was the ideal solution when accessing the attic and C cable was not feasible.

The GE Cync Smart Thermostat is a fantastic choice for those looking to upgrade their home HVAC system. With its sleek design and user-friendly interface, it adds a modern touch to any home. Installation is a breeze, thanks to the clear instructions provided. Even if you need to connect the common wire, the directions are easy to follow. Plus, GE goes the extra mile by including a c wire adapter if needed.

Connecting the thermostat to your Wi-Fi network and setting up the app is seamless. The app itself is incredibly user-friendly and offers a range of scheduling and customization options. If you already have other Cync products, you'll love how seamlessly this thermostat integrates with them. With Scenes and Routines, you can control all your devices effortlessly.

One of the standout features of the Cync thermostat is its compatibility with Google Assistant and Alexa voice commands. This allows for hands-free control of your HVAC system, making it even more convenient. Additionally, you can add remote smart sensors to the system to ensure that every corner of your home stays comfortable. These sensors are discreet and can be placed throughout your home without drawing attention.

In terms of performance, the Cync Smart Thermostat is reliable and delivers on its promises. It allows for precise temperature control and can help you save money on energy bills by adjusting settings when you're away. While it may not have the same level of sophistication as Nest or other learning thermostats, it offers all the essential features at a fraction of the price.

The C-Wire Power Adapter for Nest Thermostat is a game-changer for those who are experiencing power issues with their Nest E thermostat. This adapter provides a simple and effective solution to keep your thermostat powered at all times.

One of the common problems with the Nest E thermostat is that it tends to lose battery power frequently. However, with the C-Wire Power Adapter, this issue can be easily resolved. By following a few simple steps, you can ensure that your thermostat stays powered without any interruptions.

If you only have two wires (red and white) running from your boiler to the thermostat, here are some connection suggestions. First, disconnect the power to your boiler. Then, connect the white wire from your boiler into the W1 connector hole of your Nest E thermostat base.

Next, connect both of the power adapter wires to the base of the thermostat. One wire goes into the R connector hole, and the other wire goes into the C connector hole. Make sure to also connect the red wire from your boiler into the R connector hole of the thermostat base. The R connector hole should be able to fit both the red wire and one of the power adapter wire leads.

Once the connections are made, attach the thermostat display to its base. Turn the power back on to your boiler and plug in the C-Wire Power Adapter. The thermostat should now recognize the connected wires, and you will notice a constant power supply to your Nest E thermostat.

Additionally, the power adapter wire can be conveniently hidden from view by plugging it into an outlet in the basement directly below the thermostat. This allows for a neat and clean installation in your living room.

INTRODUCTION:

As of my third revision on 4/13/2016, I am giving the ecobee3 a 5-star rating, after initially giving it 4 stars in my review on 10/20/15. This revision is based on my experience with the 2nd Generation ecobee3, compared to the 2nd Generation Nest Thermostat that I had previously. While the Nest was a good product, the ecobee3 surpassed it in several aspects, leading me to replace the Nest with the ecobee3.

BACKGROUND:

I have a Heat Pump HVAC system with an outdoor AC compressor and an indoor air handler with electric heat strips. I originally purchased the 2nd Generation Nest Thermostat in May 2014, but it had some shortcomings, such as the Auto Away function not being practical in real-world settings. Additionally, being an Apple household, I was drawn to the ecobee3's HomeKit support, as Nest did not include it in their products. This prompted me to do extensive research and ultimately choose the ecobee3.

INSTALLATION:

The installation process for the ecobee3 was straightforward, with several reviews already covering this aspect. I found the instructions clear and easy to follow, allowing me to install the thermostat without any issues. It's worth noting that I had some previous experience with thermostat installations, which may have contributed to the smooth process. Overall, I was satisfied with the installation experience.

FEATURES AND FUNCTIONALITY:

The ecobee3 offers a range of features that greatly enhance its functionality. One standout feature is the inclusion of remote sensors in the Smarter Bundle package. These sensors allow for more accurate temperature readings in different areas of my house, providing better control over heating and cooling. The ecobee3's compatibility with Apple's HomeKit is also a major advantage for Apple users like myself, as it seamlessly integrates with other smart home devices and offers convenient control through Siri.

In terms of performance, the ecobee3 has been exceptional. It effectively tracks HVAC usage and provides detailed reports, allowing me to optimize energy efficiency. The user interface is intuitive and easy to navigate, making it simple to adjust temperature settings and create customized schedules. The ecobee3's occupancy sensor is responsive and reliable, ensuring that the thermostat adjusts accordingly when someone is present or away.

COMPARISON TO NEST:

Having previously owned the 2nd Generation Nest Thermostat, I can confidently say that the ecobee3 surpasses it in several aspects. The Auto Away function on the Nest quickly became impractical in a real-world setting, while the ecobee3's occupancy sensor has been more accurate and reliable. Additionally, the ecobee3's compatibility with Apple's HomeKit was a major deciding factor for me, as Nest did not include this support. While the Nest 3 offers some improvements over the Nest 2, such as a larger screen and a more sensitive occupancy sensor, the comparisons drawn between the ecobee3 and the Nest 2 are still relevant.

CONCLUSION:

I purchased the Ecobee Lite 3 thermostat and I must say, it has been a great addition to my smart home. Unlike some reviewers, I actually bought this product myself and I have been very satisfied with it.

Setting up the hardware was a breeze. I didn't have the C wire with my old thermostat, but there was an extra wire in the bundle that I could use as a workaround. The thermostat itself looks fantastic and adds a touch of elegance to my wall. The big numbers on the display make it easy to read the temperature from across the room, and it even changes to show the set temperature when you walk by.

The software setup was also straightforward. There's a helpful guide that takes you through the process step by step. While the built-in schedule is a bit limited, I personally don't use it as I prefer to control the thermostat manually. I connected it to HomeKit so that I can use voice commands with Siri, which has been very convenient. I also connected it to my SmartThings hub, which works seamlessly and allows me to create rules based on occupancy.

One of the best features of the Ecobee Lite 3 is its real-time access and history of temperature and humidity. This is particularly useful for me as I have a high-rise condo that is not always occupied. I can remotely power cycle the A/C system and monitor the temperature and humidity levels in real-time. This eliminates the hassle of asking neighbors for help and gives me peace of mind.

The installation and setup of the Ecobee Lite 3 took less than 30 minutes for each thermostat. The phone app provided by Ecobee is excellent and guides you through the specific hookup process for your thermostat. The system has been running flawlessly since then.

I appreciate the multiple ways I can control the thermostat – on the device itself, through the web portal, via the phone app, and even through voice commands with Siri. I have found the Ecobee web portal and app to be the most convenient for remote management.

I recently moved to the East coast and encountered some challenges with my heating system. With a six-zone boiler heating system and manual thermostats spread throughout my 4,200 sq. ft. house, it was difficult to regulate the temperature evenly in the winter. Some rooms were too cold while others were too warm, requiring constant adjustments and monitoring.

In my search for a solution, I came across the Emerson ST55 thermostat. Initially, I was hesitant because my boiler system did not have a C-wire, which is required by most smart thermostats on the market. However, after watching a YouTube review from someone with a similar two-wire system, I decided to give it a try.

Installation was a breeze with only two wires needed. I followed the instructions, inserted the batteries, and downloaded the app within 15 minutes. I did notice a slight delay of about 20-25 seconds between adjusting the temperature and the boiler kicking in, which may be specific to my system. However, once I understood this, the thermostat worked flawlessly.

One of the standout features of the Emerson ST55 is its power source. Instead of relying on a C-wire, it is powered by two AA batteries. The batteries have a long lifespan, with the reviewer in the video claiming to have used the same alkaline batteries for two years with 90% charge capacity remaining. Even if I have to replace the batteries annually, it is a cost-effective alternative to rewiring all six zones.

Additionally, I plan to replace the thermostats for my central AC units with the Emerson ST55 to have complete control over both heating and cooling from one convenient app. The integration with Alexa is also available for those interested in voice control.

I appreciate the thoughtful design of the Emerson ST55, including the built-in level on the backplate. This ensured a straight and accurate installation, which is important to me personally. The thermostat's aesthetics are pleasing as well, with a decent-sized display that is not obnoxiously large.

One minor drawback is the backlight, which does not stay on constantly when running on battery power. While this may not be a major concern in common areas, it could be important for those who have a thermostat in a bedroom and prefer a dark room at night.