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I Want a Smart Thermostat but Don't Have a C Wire - Now What?

June 09, 2021

When you’re looking for methods to decrease heating and cooling costs, getting a smart thermostat is an intelligent idea. These devices learn the temperatures you like and routine and then create an energy-efficient schedule that matches. What’s even better is that you can adjust and keep an eye on your settings from nearly anywhere with your phone, whether you’re lying in bed or on the go. (You might even be able to get a free smart thermostat depending on rebate programs from your utility company in Carpentersville.)

In many instances, adding a smart home thermostat with the support of Controlled Comfort HVAC Inc is a simple process if you have a new residence. But what if your house is older or doesn’t have the right wiring? Can you still have a smart thermostat without C wire? We’ll help you demystify the process so you can pick the ideal thermostat and receive energy savings for a long time.

What Is a C Wire and What Does It Do on a Thermostat?

Most programmable thermostats run on batteries. When you’re switching to a smart thermostat, you’ll find that many require a C wire, or common wire, for power. Without this wire, your new thermostat may cause your heating and cooling system to have malfunctions.

You can ascertain if you have a C wire by doing the following:

  1. Cut power to the thermostat at the breaker.
  2. Take off the thermostat and look at the wiring.
  3. If there are five or six multicolored wires, you have what’s required for a smart thermostat. You might be pondering what color is the C wire on a thermostat—and the answer to that is usually blue.
  4. If there are three or four thin multicolored wires, you’re close. Check the C wire isn’t tucked inside the wall. If you can’t find one, we may be able to add one for you or you may be able to use your new thermostat without one.
  5. If you have two thick wires, you may be able to use a smart thermostat with an adaptor specifically for high-voltage systems. Or you may be able to use a battery-powered smart thermostat, like the Lux Geo Wi-Fi Thermostat, if your wiring is incompatible and you don’t want to replace it.

Do Nest or ecobee Need a C Wire?

Two of the most popular brands are the Nest smart thermostat and ecobee smart thermostat. If you have two to four wires, these thermostats may work for your needs.

Nest says its thermostats are created to run on very little power and can often share it with your HVAC system. However, you may need to have a specialist like Controlled Comfort HVAC Inc add a C wire with the Nest Thermostat E or Nest Learning Thermostat if you’re experiencing power problems or a battery that’s frequently drained.

ecobee works with 24-volt systems (ones with three to six thermostat wires) and comes with a C wire adaptor. So, you’re good if you don’t have a thermostat C wire.

Depend on Controlled Comfort HVAC Inc for Your Smart Thermostat Installation Needs

At Controlled Comfort HVAC Inc, we’re always looking for approaches to keep you cozier while keeping utility costs reasonable. If you want to know more about upgrading to a smart thermostat without a C wire, give us a call at 224-412-8308. We can help you pick the right model for your home and even put in new wiring if necessary.