For heating and cooling systems, it will have a red Rc and a red Rh wire. Though both wires are red, they are not interchangeable. For the thermostat to work properly, the red wires must be connected to the correct corresponding terminal. The C, or common wire, provides smart thermostats with continual power.
The C wire's primary purpose is to give power to operate the thermostat itself. No, they're not like the RH and RC wires because these two power the systems and not the thermostat. If your unit doesn't have any, this is nothing to be worried about.
Rc. If you don't have an Rh wire, the Rc wire is the power wire for both your. heating and cooling systems. If you have an Rc and an Rh wire, the Rc wire is the power wire for your. cooling system.
Known as the common wire, (C-Wire) provides WiFi thermostats continuous power from heating (e.g. furnaces) and cooling systems (e.g. Air Conditioning systems).
If there is no hidden C-wire, you can use a G-wire instead.
For heating and cooling systems, it will have a red Rc and a red Rh wire. Though both wires are red, they are not interchangeable. For the thermostat to work properly, the red wires must be connected to the correct corresponding terminal. The C, or common wire, provides smart thermostats with continual power.
You can still install a smart thermostat without a C-wire, but it may not work as accurately or efficiently without one. Without a C-wire, a smart thermostat may disrupt Wi-Fi connectivity to other devices or can cause the HVAC system to cycle continuously, which puts more strain on the system and can lead to damage.
Rc is different from R (or Rw occassionally) in the it allows the cooling to run on a dfferent power source. Power comes in at R and out at G to run the fan, W for the heat, etc. There is only a C if the stat itself needs it to power itself. You jumper R and Rc to make the power into Rc the same as R.
Note: If you have an R, Rc or Rh wire, you can put it into the R connector on the Nest Thermostat. If you have a W2, Y2 or O/B wire, you can put it into the *O/B connector, if needed.
Putting more than one wire into a Nest thermostat connector can damage your system and your thermostat. Instead of using jumper wires, Nest Learning Thermostats use an internal jumper between the Rh and Rc connectors. A Nest Learning Thermostat will automatically use this internal jumper if your system needs it.
iDevices Thermostat requires a 24V common or 'C' wire, which provides continuous power for features like Wi-Fi connectivity and the backlit display.
The Rc wires on your thermostat are for air conditioning systems or dual transformer systems. Dual transformer systems refer to a setup with a cooling and heating transformer. Rc wires connect to the RC terminals on your thermostat.
An RC circuit is a circuit with both a resistor (R) and a capacitor (C). RC circuits are freqent element in electronic devices. They also play an important role in the transmission of electrical signals in nerve cells.
Since R and Rc both often go to the same place on a combined heating/cooling system, it's common to jumper them together at the thermostat and only run one wire. Like other Honeywell thermostats, the Lyric T5 actually has a switch to join the two together instead of a jumper wire.
The "C" wire is typically a common, or the other side of the 24 VAC transformer. The wireless Tstat would need the power source to operate. If there are unused wires in the wiring harness at the thermostat, then using one of these wires for the common is acceptable if that wire is clearly marked (as common).
Type C connectors differ in appearance compared to the previous USB types, as they are asymmetrical and have a small and thin appearance. One major difference is that the USB C is reversible; meaning it does not matter which way the connector is facing.
This is the most typical thermostat wiring style, and it applies to systems that regulate both heat and air conditioning. The wires are typically arranged as follows: red for 24-volt hot, white for heat, yellow for cooling, green for the fan, and blue for common (although the common wire may be a different color).
In many recently-constructed homes, the HVAC c-wire is already installed. However, in homes that are only a few years old or older, the wire may need to be installed as part of the new smart thermostat installation.
Nest thermostats are designed to use very little power, and in many cases they can use your system's heating and cooling wires to get enough consistent power. But sometimes, you may need to connect a common wire (C wire) or power accessory, like the Nest Power Connector, to make your system compatible.
Blue or Black (C): The Unsung Hero
Not every HVAC system uses the blue wire, but when it's there, it's crucial. The blue wire serves as the common wire, providing a return path for electrical current.
Look at your furnace/HVAC unit's control board and see if there is a "C" terminal. If so, then see which wire, if any, it's connected to. That is your "C" wire at the thermostat.
Your best bet is to hire a local electrician to complete the C-wire installation for you. These electrical pros have the skills, tools, and expertise necessary to wire your thermostat quickly and safely.
Q: what is a C wire
C stands for common. The common wire is the ground or negative wire. To complete the circuit that provides power to the thermostat you need a positive and negative wire from the 24V transformer.