Traditional Thermostat Wire Color Codes
| Color | Terminal | Use | Details |
| Black - or - Blue | C | Common 24VAC | "Neutral" side of transformer or L2 |
| Blue | B | Switched to Reversing Valve | Heat pump reversing valve energized to H ... |
| Red | R or V | Switched 24VAC | "Hot" side of transformer or L1 |
| Red | Rh or 4 | Switched 24VAC to Heat | Turn on heater |
What color is the common wire on a thermostat?
- Red-Wire - connects to the R terminal with the red wire
- RC-Wire - connects to the RC terminal RC red
- RH-Wire - connects to RH terminal RH heat
- Y-Wire - connects to the Y terminal and is for cooling stage 1 with the yellow wire
- Y2-Wire - connects to Y2 terminal and is for cooling stage 2
What color wires go where on a thermostat?
What are the 4 wires on 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)
How to wire your thermostat?
How to wire and secure your new programmable thermostat. Step 1: Wrap each wire underneath the appropriate screw, according to your notes or labels. Step 2: Use a screwdriver to tighten each screw around each wire. Step 3: Before securing the thermostat unit to the mounted base, be sure new batteries are put in and the reset button is pushed to ...
Which thermostat wire to use?
What if you don’t have Common Wire
- Install a new C wire
- Use a C wire Adapter
- Choose a thermostat that doesn’t need C wire or has an alternative solution
What color thermostat wire controls the heat?
white wireThermostat 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.
What are the 4 thermostat wires?
4 Wire Thermostat Wiring (Heat Pumps, HVAC)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).
Do I need the blue 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.
How do you identify thermostat wires?
Look for connectors that have labels that are the same as your thermostat. For instance, you might find labels like R, W, G, Y, C or O/B. You should find wires attached to these connectors that are the same color as the wires that connect to your thermostat.
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.
How do you wire a thermostat with 4 wires?
4:587:44How to replace a 4 wire thermostat - YouTubeYouTubeStart of suggested clipEnd of suggested clipSo remember blue to yellow if there's no yellow wire there and then you go green to green white toMoreSo remember blue to yellow if there's no yellow wire there and then you go green to green white to white red.
Where does the blue wire on a thermostat go?
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.
What is the blue wire on a Honeywell thermostat?
The blue wire, or C-wire, is known as the common wire. It's there to provide power to the thermostat. Older thermostats usually don't have a C-wire because they either don't need power or, if they do, they get it from a battery. Modern thermostats are a different story.
What is the black wire for on a thermostat?
This the Common Terminal, and usually, a blue or black wire is run to the transformer from this terminal to complete the circuit, and in some cases, provide power to the Thermostat. This terminal is found on thermostats designed to work with Heating Pumps and is used to power the defrost cycle on the heat pumps.
What color is common wire?
Black wire: This is a hot wire that carries electricity from the power source to the first switch in a typical 3-way setup. It's also called the “common wire” or the “line wire.” Unless the breaker is off, this black wire is always hot.
What if I have a black and blue wire on thermostat?
Black Or Blue Wire (C) The functionality of a C-wire is to offer a continuous 24V electric circuit. It is very important for a smart thermostat and helps to generate overall power. The Black or Blue wire allows you to connect it to the “C” terminal.
Does red wire go to RC or RH?
There is no standard for the colour of the RH wire, but most units use a red one. 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.
How do you test a 4 wire thermostat?
1:395:57How to Test a Thermostat with a Multimeter! - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe R and the G inside the thermostat to turn the fan on now I'm going to go ahead and turn the fanMoreThe R and the G inside the thermostat to turn the fan on now I'm going to go ahead and turn the fan off and you see that our voltage has decreased. So what we're looking at is reading 24 volts.
Is B the same as C on thermostat?
The common wire, usually labeled C, should go in the C Terminal of the Zen Thermostat. A wire labeled O, B, or O/B is used to control whether a heat pump is in heating or cooling mode. However, on some thermostats, a wire labeled B is the common wire C. In most cases, the common wire is labeled C.
How do you wire a 4 wire thermostat to a 5 wire?
5:519:47Upgrading from a 4 Wire Thermostat to a 5 Wire Thermostat - YouTubeYouTubeStart of suggested clipEnd of suggested clipBut instead of connecting the G to the G. Use that fourth wire and connect the C to the C. ThisMoreBut instead of connecting the G to the G. Use that fourth wire and connect the C to the C. This means your fan will not be operating. So what you do is you go up to the HVAC unit.
How do I wire my AC and heat thermostat?
0:365:39Thermostat Wiring to a Furnace and AC Unit! Color Code, How it Works ...YouTubeStart of suggested clipEnd of suggested clipThat's for cooling G is for fan or C is 24 volt power for cooling or is 24 volt power for heatingMoreThat's for cooling G is for fan or C is 24 volt power for cooling or is 24 volt power for heating and C is the common. So the color code we usually use W. That's white why. And that's yellow G.
What is the white wire on a thermostat?
The white wire behind your thermostat controls the heating section of your HVAC system. It is connected between the W terminal and the heat source, a furnace, or a boiler. Many houses use dual-stage heating, which is more efficient and is quite common in modern HVAC systems.
How many wires does a thermostat have?
Most modern thermostats have the standard 4 or 5-wire template, with the only difference being whether a C-wire is present or not. However, older setups or simpler systems installed in places like cabins might use a 2 or 3 wire system. 2 or 3 wire systems usually have a single-stage boiler/heater installed. In contrast, newer systems might have air conditioners, heat pumps, etc.
What is the C wire used for?
In most modern 24V systems, the C wire is used to complete the power circuit for the thermostat if it consumes electricity . The majority of modern thermostats require electricity to operate, so a C-wire is necessary for them.
What is the E terminal on a heat pump?
This terminal is used for the emergency heating back-up in your heat pump. In case the primary heating fails, heat pumps have a smaller emergency heating in them. There is no thermostat wire color specified, but it’ll be connected to the E terminal. It is better to check what wires originate from your heat pump to see what color the wire is.
What is the green wire on a blower fan?
The green wire is connected to the blower fan relay and controls the airflow through the ducts. If you have a split system, the blower fan is indoor in the air handler, while in a package unit, the blower fan is in the outdoor unit.
What wires are used for a heat pump?
Some manufacturers such as Rheem and Ruud use the dark blue wire to connect B-terminal and the reversing valve. In this case, the reversing valve is used in heating mode.
What wire is used to connect a heat pump to a furnace?
In this case, your furnace will have low fire and high fire settings. If you have a two-stage heating system, a brown wire will be used to connect the W2 terminal to the dual-stage switch on your furnace or boiler. Heat pumps usually use staging for additional heating (auxiliary heating). In that case, the heat pump is also connected to the W2 terminal through the brown wire.
What is the color of the thermostat wires?
without air conditioning). Typically, the two wires are red and white (see above for information on where they are connected).
What color wires are used for a thermostat?
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).
What type of wire is used for a digital thermostat?
There is a 24-volt hot wire, a 24-volt common wire, and a white wire.
What is thermostat wire?
About thermostat wire. Thermostat wire is a bundle of 18 or 20 gauge copper conductors. Each individual conductor is sheathed in a protective, flexible coating of a different color. The exact number of colored wires varies, as does the gauge of the wires. 18 gauge wires are slightly thicker than 20 gauge wires.
Where are thermostat wires stripped?
At your thermostat, thermostat wires emerge from the wall and are stripped at the ends to reveal the copper inside. The copper ends are hooked to terminals on the thermostat’s base. Over in your furnace and other accessories, the other ends of these wires are hooked to similarly labeled terminals.
Is there a standard color for thermostat wire?
Thermostat wire color guide. Colors and their usages vary by system and installation – there is no standard, and furnaces/thermostats don’t enforce the usage of one color over another. As far as a thermostat or furnace is concerned, all the copper wires in the bundle are exactly the same.
What color wire is used for thermostat?
These are not likely to be found in every thermostat, so check with your manufacturers' instructions. The white wire connects to the W terminal and triggers the heating.
What is the black wire on a thermostat?
The black wire may be linked to the C terminal, which controls the transformer. This is most often seen in electronic thermostats where only 24 volts are required. C terminals are connected to the common wire, which is most often black, but can also be other colors.
What is the green wire on a blower?
The green wire connects to the G terminal and is used to control fan relays, triggering the blower fan. This system can be triggered by programming the thermostat to reach a certain temperature. Once this degree is reached, the G terminal will be given power, causing the blower to start up.
What color wires are used in heat pumps?
The most essential colors are red, green, and yellow, although you may find up to eight different wires in a heat pump thermostat, or as few as five in a more common hot water system. The red wire is connected to terminals beginning with the letter R, which include R, RH, and RC units, depending upon how the thermostat is being used.
What is the blue wire on a heat pump?
Dark blue wires connect to the B terminal , found in heat pumps, although this may be an orange wire connecting to the O terminal in some makes. Most brands use the O pump, as this connects to a valve used to trigger cooling.
What is the yellow wire on an air conditioner?
The yellow wire is often seen in air conditioning units and attaches to the compressor. Yellow wires connect to the Y terminal and the wire is sometimes spliced, being connected to a compressor and the condenser, although this is not necessary.
Why is it so hard to install a thermostat?
These color codes are vitally important in connecting the right wires to the corresponding terminals. Failure to properly link these can lead to failures in the system, including short circuits, which can lead to fires. Therefore, taking the time to learn all of the possible combinations of wires and colors is essential to keeping the family safe.
What is artificial intelligence thermostat?
Artificial Intelligence embedded in some of the most expensive thermostats is pushing these to the absolute limit. Not only are you able to create settings based on your preferences, but the thermostat will gather data based on your particular system and configuration in order to optimize comfort and energy savings. These units will also collect data over time and be able to predict certain events which occur on a regular basis and anticipate them better every single time.
What is the purpose of a programmable thermostat?
The main purpose of a programmable thermostat is to give you full control over the temperature levels within your home. Not only is it installed for comfort purposes, but can be configured to generate significant energy savings as you can easily turn off appliances when they are not needed.
Do thermostat labels go missing?
We recommend to always work with the labels instead of colors, but they do go missing much more frequently than colors of the wires! Therefore, here’s the color to label diagram for a typical thermostat:
What does the yellow wire on a compressor mean?
So, this is what you might expect to see in terms of colored wires and what they mean: White – The white wire is what connects to the (auxiliary) heat on your system. Yellow – The yellow wire connects to your compressor. Green – The green wire connects to the fan.
What does RC stand for in electrical?
Red – Now, there can be two separate wires for this. One is for cool and the other is for heat, hence the abbreviation “RH” and “RC”.
What is the black wire on a thermostat?
The black wire or blue wire (either color is used) is the C – “Common” wire. What does the C wire do? C wire is connected to the transformer and completes the 24V electric circuit. Newer thermostats have a continuously looped 24V circuit; in older models, the loop is completed only when the power is required (when you turn the AC on, for example).
What is the orange thermostat wire?
“O” or the orange thermostat wire is for reverse valve cooling. Most bigger heat pump manufacturers like Trane, Goodman, Lennox, and so on have the orange wire that goes to the condenser (located in the outdoor unit of heat pumps).
What wire does an air conditioner thermostat use?
All air conditioner thermostats have a red wire for power. You may also have Rc or Rh terminals for dual transformer systems; these are special cases in thermostat wiring.
What is the red wire on an air conditioner?
Thermostat Red Wire (“R” or “Rc” Wire) Red wire or “R” wire is the power wire. They originate in the transformer (air conditioners; in the air handler) and provide the 24-hour volt AC power. All air conditioner thermostats have a red wire for power.
How many wires does a Honeywell thermostat have?
With the basic Honeywell thermostat, you will find: 8 wire sockets to the left. 8 wire sockets to the right. Before we take the flathead screw to unscrew these, let’s first familiarize ourselves with the crucial part of any thermostat wiring: Wire codes and colors. Here’s where the thermostat wires go:
What is a thermostat?
Thermostats are the ultimate control hubs for HVAC devices such as furnaces and air conditioners. Thermostat wiring is a useful skill to know if you have to replace an old thermostat or just check if something is wrong with the new thermostat. With a little help, you can learn how to install a thermostat on your own.
How many sockets does a thermostat have?
As you can see on the thermostat base, you have 16 sockets, with letters C, R, W1, W2, O/B, G, Y1, Y2, BK, 2x RS, 2x ODT, AUX NO, AUX C, and AUX NC. With 2 wire, 3 wire, and 4 wire thermostats you don’t have all of these. That’s normal. You might also notice that all sockets don’t wire in them. That’s standard as well.
