Can I Install A Smart Thermostat Without A C-Wire - Automate Your Crib (2024)

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Are you getting ready to install a smart thermostat and realized there no c-wire or common wire? If so, you have come to the right article to solve your problem.

When my wife and I recently purchased our first house, I was really excited to try out new smart home products, and the first device on our list was theecobeeSmartThermostats with Voice Control.

Since we were new homeowners, and we did not want to be overwhelmed with high utility bills we decided to switch our existing thermostat to a smart thermostat.

From our research, having a smart thermostat vs a digital Thermostat can help to reduce our energy usage, which will then reduce our energy billand allow us to have a more sustainable home.

Also, by having a smart thermostat we are able to control our heating and cooling system through our phone to adjust the temperature even when we are not home.

Now, after receiving ourecobee, reading the instructions, and watching a fewsmart home YouTube videoson how to install a smart thermostat, I was ready to go.

After removing the existing thermostat, I realized there was one potential installation problem,there was no c-wire.

Unfortunately, the previous thermostat didn’t require one and most older homes do not have a C-wire installed.

The good news there are several options to install asmart thermostatwithout a C-wire, it just takes some additional work.

The following are the steps I took on how to install a smart thermostat without a C-wire. In the example below, I used anecobeethermostat during this installation.

What is a c-wire?

Before we begin, let’s understand what is a C-wire also known as a commonwire.

A C-wire provides a continuous flow of electricity to your Wi-Fi thermostats which are connected to your heating and cooling system.

C-wire is usually blue or black for 24-volt power to the thermostat.

The old thermostat didn’t require a C-wire as most typically run on two or three AA-battery. The older thermostat only needed enough power for the small screen display in front of the thermostat.

Today’s thermostat needs power for geolocation, backlit display, and Wi-Fi functionality. Unfortunately, without a C-wire connected to some labeled terminal, you can’t use a smart thermostat.

How to Install a smart thermostat without a c-wire

First thing first,turn off the power to the HVAC system. You can also do this by turning off the master switch on your circuit box. The circuit box isusuallylocated in your attic, basem*nt, closet, or garage.

Next, check for a C-wire by detaching your existing thermostat andtaking a lookat the wires connected to it.

If you see a terminal labeled “C” then you have a C-wire, if there is not, go to your furnace or HVAC system (usually in the Attic, basem*nt, or garage) and check the source.

There is a chance your HVAC control board has a common wire that wasn’t needed during the installation for your existing thermostat, which the wire can be hidden in the wall.

If there no C-wire on the control board, then according toecobeeinstructions you will need to use their PEK or also known as the Power Extender Kit.

The PEK adapter is used as a replacement for the C-wire and will only work with the following,ecobeeSmartThermostat,ecobee4,ecobee3, andecobee3 Lite thermostats.

Before we go any further, I would like to state this.

I am not a certified electrician and if you continue, you are doing this install at your own risk.

For any reason you are uncomfortable, you should contactecobeefor instructions or hire your local licensed electrician.

Trust me, I understand, as I was very nervous, especially being a new homeowner. I had no clue what I was doing, but I was willing to try.

Now, that we have that out of the waylet’sbegin.

Step – 1 Get out your tools

Before you remove the wires from the backplate, double-check to see if the power is off with a voltage tester. If you don’t have an electric tester tool kit, you canfind one at your nearest big-box retailer or online.

It’s always good to test the wires for power before touching them. Here is a checklist of the tools you may need before you start:

• Drill
• Small screwdriver
• Phillips screwdriver
• Hammer
• Pencil
• Wire stripper
• Voltage tester
• Flashlight
• Touch up paint (Use the same paint and color matching wall)

Step – 2 Identify the old wiring

After you confirmed the power is off, the next step is to identify the old wiring from the existing thermostat. Once you have identified the wires, start removing and labeling them with each sticker labelecobeeprovides.

Or take a snap picture of the wires that are located on the back of your old thermostat.I did both.

Step 3 – Remove the existing backplate

Gently remove the backplate from the wall. It’s usually held in place by two to four screws into the wall.

Step 4 – Install the new smart thermostat

Now, here comes the solution to the problem. Since we already established you do not have a C-wire, you will need to go to your furnace or HAVC system with the Power Extender Kit (PEK) adapterecobeeprovides you.

Note: The PEK requires certain wires for your system in order to work.

• 4 Wires: y/y1, R, G, W/W1
• 3 Wires: R, y/y1, and G

Open the furnace or HVAC cover or covers off, and take a picture of the wires that are connected to the control board. This will be good for reference.

Step 5 – Disconnect the wires from the control board

You can now label each wire as we did with the thermostat wires for assistance. Next, disconnect theR,Y, G,and W wires from the control board, and re-connect them to the matching white terminal blocks located on the PEK.

Step 6 –Install the PEK adapter

Once you label the wires, you can connect the five white wires that are coming out of the Power Extender Kit to the terminals on the control board. Here is an example below of how your control board and PEK should look:

Step 7 – Confirmed wires are connected

After you’ve confirmed all the wires are securely connected, close your furnace or HVAC system and return to theecobee.

Step 8 – Wiring your newthermostat

Now, here comes the easy part. Install the larger trim plate for theecobee. Pull the wires through the hole located in the middle of the backplate.

Next, insert each wire labeled to the matching terminal on theecobee. In this order:

• R or RC wire – RC terminal
• G wire – C terminal
• Y wire – PEK terminal
• W wire – W1 terminal

Step 9 – Turn your HVAC system back on

Press yourecobeethermostat on the wall mount and click it shut, and restore power to your HVAC system back on!

Thermostat Troubleshoot:

Our Air conditioning won’t turn on

After restoring the power to our HVAC, theecobeepowered on but we noticed an issue, our air conditioning wasn’t turning on.

We felt air coming out of the vents but it wasn’t cooling down the house. We went over the instructions, check all the wires from the thermostat to the furnace, and ensure they are securely connected to the terminals.

There seem to be no connecting issues, so, we gave it a day to see if anything will change.

We contactedecobeesupport team

The next morning the air conditioner still wasn’t turning on, we decided to contactecobee(877-932-6233)for further assistance.

We explained the problem to Devon fromthe ecobeesupport team. To help him identify any potential issues we sent clear photos of the wiring from theecobeethermostat, HVAC control board, and PEK.

Everything I did was correct but there was an issue with the old wiring.

As I mentioned earlier, we recently purchased our first house, and the previous owner of the house did a lot of the electrical wiring (DIY electrical work) himself which caused the issue.

Eventually, we found out, that we had faulty wiring throughout our home but that’s a whole different topic for a later time.

Once Devon was able to figure out a solution without us calling an electrician, which would have cost hundreds ofdollars.

He had me adjust the wiring of the PEK adapter, which allowed the thermostat to properly engage the air-conditioning.

Devon fromecobeewas a lifesaver and helped us solve our problem without spending any additional cost.

What to do if yoursmart thermostat is not working properly?

If you are running into any issues with yoursmart thermostat it could be one of a few things. So, you’ll want to ensure that you follow the steps below to make sure that everything is working properly.

1. Check the wiring at yoursmart thermostat

2. Check the wiring at your air handler/furnace

3. Check the equipment configuration

4. Check your threshold settings

If you are still having trouble, contactthe smart thermostat company or if you have an ecobee, contact 877-932-6233 orsend a message, for further assistance.

How to power a smart thermostat with an external transformer?

Now, to be honest, I have not tried to install a smart thermostat with an external transformer, but I thought this wasaneasy solution to the problem without hiring a professional electrician.

A licensed electrician can cost you an average of between $200 and $400 to install a new thermostat wire in the wall to your boiler orfurnace.

In the video below, he used a Honeywell thermostatduring this installation, but this can work with any Wi-Fi thermostat without a c (common) wire.

If you are interested in a 24-volt transformer adapter, you can find them on Amazon.

Final Note

After I was done installing theecobeesmart thermostat without a c-wire, it was an exciting moment to know I did it, and it workswithout hiring a professional electrician to do the job.

The only hiccup was thefaulty wiring, but I was able to still do the job with some assistance fromthe ecobeesupport team.

Ecobeeor any smart thermostatmakes the setup process easy by eitherdownloading the app, watching theYouTube video,or following theinstructionsthat come with the product.

If you have questions you can always contact the company before purchasing the device.

Thanks toecobee,we can save money and control the temperature from the comfort of our bed.

Please, don’t forget to check out therecommended gadgetspage for the best tech for your buck.

For more useful tips and tricks with Home automation, please continue to check outAutomateYourCrib.com.

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