Can I connect C wire to R?

If the black wire on the R terminal goes to the thermostat and only the thermostat, you can safely move it over to the C terminal. The AC and humidistat being hooked up to C is correct. R and C together carry the 24v power that a smart thermostat (and some programmable models) use for power.

Where does C wire attach to furnace?





Quote from the video:
Quote from Youtube video: You would typically connect. This a/c wire to be the C terminal on the board on the control board on in the furnace.

What is the R terminal used for on a thermostat?

R – The R terminal is the power for the thermostat. This comes from the transformer usually located in the air handler for split systems but you may find the transformer in the condensing unit.

Do I need a jumper from R to RC?

If you have a wire in the R terminal, and another wire (not a jumper) in the RC terminal, you will not need to connect the R and RC terminals. See our Basic Wiring article for more info here.

How do I bypass the C wire on my thermostat?

Quote from the video:
Quote from Youtube video: Connect the extra wire to the C terminal of Union thermostat trace the extra unused wire from the thermostat to the furnace board make sure it's connected to the C.

How do you run a C wire from furnace to thermostat?





Quote from the video:
Quote from Youtube video: Basically take the the plate here take your transformer. You're gonna make your connections. For everything just like they were on the thermostat that you took off with the exception of two.

Can I connect three wires to the furnace C terminal?

If the terminals are allowed to have more than one wire, it will say so on the terminal block or in the manufacturer’s documentation. Two wires per terminal in HVAC work is common (though not usually correct), while 3 or more will tend to use a pigtail.

What is the C wire on a furnace?

WHAT IS A C-WIRE? A C-wire, or a common wire, runs from your low voltage heating system (24v) and carries continuous power to your thermostat. In today’s electric market, most newer heating and cooling systems have C-wires, which guarantees compatibility for the installation of all smart thermostats.

Does C wire have voltage?

The C wire, a.k.a. the “common wire”, allows a constant flow of 24 VAC (volts AC) power to a smart thermostat. However, the C wire doesn’t provide the actual source of power to the thermostat. The wires that provide the source of power are the R wires (or hot wires).

Can I use RC wire as C wire?



No the Rc is the red wire. You need 5 wires or more for this to run with all the functions. You can use one of the other wires but you have to drop control of the fan. It will only come on when furnace comes on.

Does the red wire go to R or RC on thermostat?

In a thermostat, the R wire is responsible for powering the entire HVAC system (through a transformer). If you have both an Rh (Red-heat for powering the heating) and an Rc (Red-cool for powering the cooling), then the R wire can be connected to either Rh or Rc.

Do I use R or RC on thermostat?

If you have two wires, R or RH go into the R terminal and RC into the RC terminal. If you have more than one wire (for example, you have a wire labeled R and another wire labeled Rc), remove any jumpers between the R and Rc terminals or push the switch to open the RC terminal to insert a wire.

Is RC wire same as R wire?



RC is no different and simply means red cooling. The wire is generally red, although there is no color standardization — but more importantly, the “R” really means that the wire and terminal are hot; it’s a live electrical wire. The RC wire connects to the RC terminal, which controls the cooling system.

Why is there a jumper between R and RC?

In most cases, the heating and cooling system share a single transformer by leaving the jumper in the lower right corner it connects the RC and RH to power heat and cool features.

What happens if you wire a thermostat wrong?

Potential consequences of improper installation could include: Electric shock. Blowing a circuit breaker. Damaging the thermostat unit, the electrical system or even the AC/furnace unit itself.

Can thermostat wires shock you?

Virtually all room thermostats operate on low voltage that carries little risk of harmful electric shock. However, it is always wise to shut off power to a thermostat at the service panel before examining or working on it.

Can you change a thermostat without shutting off power?



The short answer is no, it’s not OK – you increased your risk of electrocution and that’s never a good thing specially for a DIYer.

How many thermostat wires do I need?

The most basic thermostat has 2 wires; usually a red and a white wire. Two wire thermostat wiring is used for furnaces only and usually doesn’t need a “C” or “Common” wire. That’s why we only need two wires: Red wire for power (24h).

Can you install nest without C wire?

You can install a Nest Thermostat without a C-wire by using a C-wire adapter, that mimics a traditional C-Wire without you having to wire it.

What is the Blue C wire on a thermostat?

The Blue or C Wire



C wires or varying colors apply to every thermostat, but blue C wires belong to thermostats attached to a heat pump. Blue wires are for heat pumps. This wire connects to terminal B on your thermostat.