What is the blue wire for on a thermostat

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.

What color is blue wire in thermostat?

Blue “C” wires are most common in thermostats that connect to your heat pump. This wire must connect to the B terminal on the thermostat. “C” wires are also frequently black.

Where does the blue wire go on a White Rodgers thermostat?

A blue or black wire is meant to be connected at a terminal marked ‘C,’ while a white wire should connect at terminal ‘W. ‘ The wire for terminal ‘E’ is usually a brown one, and ‘Y’ and ‘Y2’ are usually yellow. A wire for terminal ‘G’ is typically green, while ‘O’ is orange and ‘B’ is blue.

What does each color thermostat wire do?

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).

Where do I connect the blue wire on my Nest thermostat?

1. A brown wire is mostly likely a heat pump wire and should be connected to the O/B connector on the Nest thermostat.
2. If the B wire is blue, it should most likely be connected to the C connector.

What are the wires in a thermostat?

• Red wire for power (24V).
• White wire for heating (connected to W or W1 terminal).
• Green wire for fans.
• Blue or yellow wire for cooling (connected to Y).
• Black wire for “C” or “Common” wire.

Where do thermostat wires go?

Thermostat Wiring Tips If your thermostat controls your heat, you will have a white wire. The Y wire is yellow and connects to your air conditioning compressor. The G wire is green and connects to the fan. Rc and Rh: The red wire(s) are the power source for your thermostat.

Where does the blue wire go on a Honeywell thermostat?

Wiring a New Thermostat First, isolate the power to the system to keep from blowing any fuses or getting a slight shock. Next, connect it to the C terminal and it becomes the C-wire. Be sure the blue wire is connected to the C at the control panel in the heating or cooling appliance.

What color wire goes where on a Honeywell thermostat?

Meaning of Wiring Terminal Letters W (white) controls the auxiliary heating elements. Y (yellow) controls the compressor on the cooling system. G (green) controls the fan. C (blue or black) provides a return path to the transformer.

Why does my thermostat have a jumper wire?

Most of your current thermostat’s wires will be connected to your thermostat and go through the wall to connect to your HVAC system. However, some thermostats will have a jumper wire that doesn’t go back through the wall to connect to your system. Instead, a short jumper wire connects two thermostat terminals together.

Article first time published on

What color is the C wire on a thermostat?

Blue wires are also called “C” wires because they are the Common wire. C wires are necessary for any “smart” thermostat that needs to be connected to a power source 24/7, regardless of your heat pump type.

What wiring is needed for a Nest thermostat?

Nest thermostats are designed to work without a C wire in most homes. But some systems may require a C wire for consistent power.

What is G wire on thermostat?

G: The G terminal controls the fan relay and is responsible for turning the blower fan on and off automatically or manually via the thermostat.

What color is the common wire?

Red, Black, and White are the colors of switch wiring for three-ways. Red and Black are connected to the switches if the White is used for neutral. The White is often referred to as Common, but the colored wires are also used as hot wires.

What color is b wire on thermostat?

MarkingWire Color CodeDescriptionY2YellowSecondary cool call relayGGreenFan relayOOrangeChange-over relay to cool relayBBlueChange-over relay to heat relay

Where is the C wire on a thermostat?

Simply remove your current thermostat face from its baseplate and look for the terminal labeled with the letter “c.” If this terminal has a wire attached to it, you have an active “c-wire.” If you don’t see a wire connected to your “c” terminal, you have a few options.

Why is there a jumper between R and RC?

Effectively there isn’t a second RH wire, although there is an RH terminal. However, the heating still needs to be controlled, so a wire known as a jumper is connected between the RC and the RH terminals so that power gets to the heating control part of the thermostat.

What is the Y2 wire on a thermostat?

Y2 is the thermostat wire for second stage of cooling. Y wire is for the first compressor (air conditioner units) and Y2 wire is for the second compressors (air conditioner unit). Y2 wires apply only if you have two air conditioner compressor units running from one AC thermostat.

Does White Rodgers thermostat use C wire?

White Rodgers – C-Wire – Thermostats – Heating, Venting & Cooling – The Home Depot.

Why is my White Rodgers thermostat not working?

Most White-Rodgers digital thermostats run on AA batteries, which can cause the unit to malfunction if they’re low or dead. Look for a low battery indicator on the screen if you have an electronic thermostat. … After replacing the batteries, turn the system back on and see if that fixes the issue.

What happens if you short thermostat wires?

If you short the R wire to the C wire, you’ve effectively created a very low resistance closed circuit across the secondary of the 24V transformer in the HVAC system. … Since the thermostat is on the secondary side of the transformer, the circuit breaker for the HVAC system may react too slowly, or not at all.

What is the difference between RH and RC thermostat wires?

The RH wire refers to “red heating” which means that this is the connection you need in order to power the heating system of your air conditioning unit. … The RC wire, on the other hand, refers to “red cooling”. It’s the same with the RH wire in that it powers the thermostat. For the RC, it powers the cooling system.

What does the C wire connect to?

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.