Honeywell (and others such as Trane) use a C wire on models that use WiFi or voice recognition or Z-wave so they can have a 24V connection. All thermostats use low voltage from the other connectors and typically use the batteries as a backup when there's no C wire.
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). C-Wires are required on all Resideo WiFi thermostats.
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.
In order to use the rth6580wf you are going to have to have a C wire.
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.
Do all Smart Thermostats Require a C-Wire? Though all smart thermostats can use a C-wire and arguably may be more reliable with the use of one, not all smart thermostats require a C-wire to function. Some models, such as Google Nest, are designed to work even if your home doesn't have a C-wire.
This Honeywell programmable thermostat uses an internal disposable battery for its primary power. A "C" wire is not required. It will work with a 2 wire system.
This Honeywell Home Thermostat does NOT contain mercury. Also, know that this Honeywell Home Thermostat does NOT use batteries.
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. If no "C" terminal that you will not have a "C" wire and could possibly hook one up if you have the wiring diagram for the furnace.
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.
If there isn't a C wire, you have 2 options: get a pro installer to run a new C wire from your system to your thermostat, which can be expensive, or you can install the Nest Power Connector, which is usually simpler and more affordable.
Most homeowners decide hiring a nearby electrician is worth the C-wire installation cost to ensure everything works right on the first try. Keep in mind that the typical cost to install a C-wire is $120 to $200.
If there is no hidden C-wire, you can use a G-wire instead. However, you will not be able to use your fan independently when the heating or cooling isn't running.
The most common configuration is five wires. However, you could see as few as two and many as ten. Make a note of any present wire not connected to a terminal. Do not label these wires.
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.
Honeywell (and others such as Trane) use a C wire on models that use WiFi or voice recognition or Z-wave so they can have a 24V connection. All thermostats use low voltage from the other connectors and typically use the batteries as a backup when there's no C wire.
A: Honeywell RTH9585WF wirelessly connected to my home Wi-Fi network just like a tablet or laptop. No additional modules were required. A: No batteries. This thermostat requires a constant live 24 volts.
A C wire, connected to C on the equipment, is required for the thermostat to power itself. Verify the furnace / air handler door is closed, the power switch is on, and the breakers are on. Confirm you have a C wire in the C terminal.
The RTH2300 series does not allow for a C wire connection and the C wire should not be use. Tape the wire off with electrical tape and tuck it back in the wall.
Q: what is a C wire
A: 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.
A "C" wire is the common wire that completes the electrical circuit from your transformer to your thermostat. "R" and "C" complete the 24v AC circuit to power the smart thermostat. Older "dumb" thermostats don't need power to operate things like wifi.