What is the wiring for a heat pump thermostat?
Heat Pump Thermostat Wiring Diagram. Heat pump thermostat wiring - A typical wire color and terminal diagram. As shown in the diagram, you will need to power up the thermostat and the 24V AC power is connected to the R and C terminals. The color of wire R is usually RED and C is BLACK. C is known as the common terminal.
What is the Red Wire on a thermostat?
RH and RC single power for HEAT and COOL. In most thermostat wiring hookups the red wire is the power source for the system. W Heat control (usually this is the white wire) In most thermostat wiring hookups the white wire is used to switch heat on or off from the thermostat.
What does the W wire do on a thermostat?
This controls the reversing valve in the condensing unit. The reversing valve switches the condenser from heating to cooling and vice versa, depending on the thermostat setting. W Wire Terminal Designation - This color is typically white and goes to the W terminal. In a heat pump, this is for the backup heat source.
What is the W terminal on a heat pump?
W Wire Terminal Designation - This color is typically white and goes to the W terminal. In a heat pump, this is for the backup heat source. Whether it is electric heat strips or a gas furnace (dual fuel), the W terminal controls this.
What color is L wire on thermostat?
Thermostat Wiring Color Code ChartMarkingWire Color CodeDescriptionOOrangeChange-over relay to cool relayBBlueChange-over relay to heat relayAHeat and cool active to any relayLEmergency heat active lamp12 more rows
What is L on Honeywell?
C – Common. U – Humidifier, Dehumidifier, or Ventilator control. L/A – A – Input for heat pump fault. O/B – Reversing valve for Heat Pump systems. E – Emergency Heat.
What is L1 and L2 in thermostat wiring?
For double-pole thermostats: Using wire connectors, connect a hot supply wire, which is typically black, to thermostat wire one (typically it is marked L1 or Line). Step 8. Connect the remaining supply wire, which is typically white, to the second thermostat wire (typically marked L2 or Line).
What do the letters on thermostat wires mean?
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). You can also refer to the Conductor Color Chart (see Chart 6, thermostat wire).
How do I wire a Honeywell thermostat to a heat pump?
2:459:34Heat Pump Thermostat Wiring Explained! Colors, Terminals ...YouTubeStart of suggested clipEnd of suggested clipIt's gonna connect in the thermostat. It's gonna go back over to the air handler control board onceMoreIt's gonna connect in the thermostat. It's gonna go back over to the air handler control board once that air handler control board sees the 24 volts on the g terminal.
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.
What does L1 and L2 mean HVAC?
L1 and L2 represent the two poles on an AC power supply. L1 and L2 provide power to the components on the line side of the circuit. The control side of the circuit will not have lines for L1 and L2.
Is L1 load or supply?
A one way light switch has two terminals which is a common marked as COM or C. The common is for the live wire that supplies the input voltage to the switch. The other terminal is marked as L1 and is the output to the light fixture.
What is L1 and T1 on thermostat?
L is for line or supply. T is for load. Basically L is power in and T is power out. If you are trying to find which wire is coming from the panel, yes the power must be on. The one from the panel will show voltage.
Does my heat pump use O or B wire?
O/BIf you have a heat pump and your thermostat doesn't have a separate wire labeled O, then the wire labeled B should be connected to the Nest thermostat's O/B connector.
How do you identify thermostat wires?
Here is the industry standard color code for thermostat wires used for most systems:The W wire is connected to your heating system. ... 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.More items...
What are the 5 thermostat wires?
5 Wire Thermostat Wiring (Any HVAC Device – Air Conditioners, Heat Pumps, Furnaces, etc.)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.
What is L1 L2 on a furnace?
The word "circuit" is derived from the Latin, meaning "circle." L1 or L2, "hot" or "neutral" are merely words. Your typical outlet uses BOTH main connections, the slots, to power a device. The same current is moving through BOTH wires. On a 208 - 230 volt circuit used to power a condensing unit, same thing applies.
What does T1 and T2 mean on a thermostat?
When you call up the FreezeAlarm, you can tell it to supply the low voltage power to either thermostat #1 (T1) or to thermostat #2 (T2). Whichever ther- mostat is getting power is the one controlling the furnace. To to turn on the heat, you don't need the second thermostat.
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 is S1 and S2 on thermostat?
S, S1, S2: These wires run directly outside and provide outdoor temperature information to the thermostat.
What color wire goes where?
The colors such as Red are for hot and goes to the R terminal. Same with the other colors and terminals. However, depending on who wired the thermostat last, they may not have followed the wiring color code. Therefore, before removing any of the old wires, take a picture of the wires and where they are terminated on the sub-base of the old thermostat. Use your cell phone to take the photo for later reference.
Can you use an air conditioner with electric heating strips?
That is for use for heat pumps. You should 100% make sure that you have a heat pump system and not an air conditioner with electric heating strips as it is a common mistake for people to misidentify their HVAC systems. Make sure you do not make these same mistakes others make. Air conditioners are different because the reversing valve and defrost controls are unnecessary.
Can a heat pump have two transformers?
If you have a conventional split system air conditioner or heat pump and there is a jumper from RC to RH, then you have a single transformer and do not have to worry about two transformers in your system.
What is the W terminal on a heat pump?
W Wire Terminal Designation - This color is typically white and goes to the W terminal. In a heat pump, this is for the backup heat source. Whether it is electric heat strips or a gas furnace (dual fuel), the W terminal controls this. This wire will also run to the air handler/furnace and the condenser. The defrost control board in the condenser will automatically defrost the system. When it goes into defrost mode, the backup heat is energized. In most cases, if you are changing your thermostat, you do not have to worry about any wiring at the condenser.
What is the Y wire on a heat pump?
Y Wire Terminal Designation - This color is usually a yellow wire and goes to the Y terminal. In a heat pump, this is for heating and cooling. It energizes the compressor contactor in the condenser.
What is the R wire?
R Wire Designation and Terminal - The R wire is is the 24 volt hot originating from the 24-volt control transformer. That is the power to energize the control relays and contactors in your system. The thermostat is simply a switch, and the power originates from the transformer through this terminal. For those with a power stealing thermostat (without batteries), the is also where the thermostat gets its power. Finally, the color of the R wire is typically red.
What is the best backup heat source for a heat pump?
If the temperature falls below a certain point, the heat pump needs a supplemental heat source to keep up with the thermostat setting. The most basic method of backup or supplemental heating for heat pumps is electric heat strips. The next most common backup heating source is a gas furnace.
Why do heat pumps need a backup?
Additionally, air-source heat pumps have backup methods of heating for two reasons. When the heat pump system kicks into defrost, it needs a backup heat source.
What is W2 thermostat?
In some cases, depending on your system, W2 can be used simply for emergency heat, which is your backup heat source. It is sometimes referred to as auxiliary heating, and it is used in case something goes wrong with the condensing unit. In some cases, the terminal for the thermostat will be labeled Aux/E/W2.
Can you wire a heat pump to an air conditioner?
Wiring a heat pump is different than wiring an air conditioner with a gas furnace or boiler. There are extra controls in heat pumps that require extra attention and understanding to get the wiring correct. Additionally, changing an older mechanical thermostat to a newer digital thermostat will require some extra wiring that also may require you to pull new wire to the thermostat from the air handler.
What does each thermostat wire do?
Knowing what each thermostat wire does can help in wiring up a new or replacement room thermostat. This data can also be helpful if thermostat wires have become mixed-up or improperly color-coded by allowing you to trace wires back to their control connection point.
What is the orange wire on a thermostat?
In most thermostat wiring hookups the orange wire is used to control a reversing valve - switching from heating to cooling mode or vice-versa. See (B and O) above. R. RH and RC single power for HEAT and COOL. In most thermostat wiring hookups the red wire is the power source for the system.
What is the wire used to control a fan?
In most thermostat hookups the green wire is used to control a fan. In most thermostat wiring hookups the orange wire is used to control a reversing valve - switching from heating to cooling mode or vice-versa. In most thermostat wiring hookups the red wire is the power source for the system.
Does a backup heat switch on a thermostat?
IF the thermostat wire bundle routed to the thermostat included enough wires to operate all of the needed functions and IF the model thermostat includes both heating and cooling, the answer is probably yes. Backup heat will typically switch on automagically depending on outdoor temperature.
Where do you put the C wire on a thermostat?
In some cases, one of those wires may be your common. If you have a C wire, place it into the C terminal on your wall plate. Let's take a look at the G wire. This wire will go to the G terminal on your new thermostat. For the Y, Y1, and Y2 wires, Y or Y1 will go to the Y terminal, and Y2 will go to the Y2 terminal.
How many wires does a thermostat use?
The thermostat uses 1 wire to control each of your HVAC system’s primary functions, such as heating, cooling, fan, etc. See the diagram below for what each wire controls on your system:
What to do if you see terminals labeled A B C or 1 2 3?
If you see terminals labeled A B C, or 1 2 3 then your new thermostat may not be directly compatible, as your system requires a communicating thermostat.
Do you tape off the B wire on a heat pump?
If you have separate wires for O and B, you will want to tape off the B wire so it can’t make contact, and the O wire will be connected to the O/B terminal on your thermostat. If your O or B terminal shares a label with another wire, typically W, you’ll need to identify whether you have a heat pump system or not.
Can you label wires that are not connected to a terminal?
Any wire that is present, but not connected to a terminal you will want to make a note of, but you will not label these wires.
Where does Y1 go on a wire?
For the Y, Y1, and Y2 wires, Y or Y1 will go to the Y terminal, and Y2 will go to the Y2 terminal.
Do thermostats have a jumper switch?
If you just have one wire, regardless if it's labeled RC, it will go into the R terminal, and the jumper connecting terminals R and RC will be in place. Some thermostats have a jumper switch, some have a metal staple, others may have a plug, and the jumper may also just be a wire connecting the two terminals.
What does orange wire mean on a heat pump?
If the wire in the O/B-W connector is orange: you probably have a heat pump. (Check the picture above.)
Why is the common wire used in Nest thermostats?
Because the common wire is used to provide consistent power to the thermostat, it’s important to determine what function a wire labeled B serves before connect ing it to a Nest thermostat.
How to tell if a B wire is a common wire?
How to tell if a B wire is really a common or C wire. Wires labeled B typically should go into a Nest thermostat's O/B connector. But for some systems the wire in the thermostat 's B connector is actually a common or C wire. Common wires should go in your Nest thermostat's C connector.
How to check if Nest thermostat is compatible?
Usually, you just remove your thermostat’s cover and enter the wires you find into the compatibility checker. The Nest app and Home app will also let you know if your system is compatible and give you a wiring diagram for installation.
What happens if you put wires in the wrong thermostat?
If you put wires into the wrong thermostat connectors during setup can, this can cause your system to malfunction or possibly damage it.
What is a jumper wire?
Jumper wires connect two thermostat terminals together (often Rc and Rh), but they aren’t “two label” wires. Jumpers aren’t connected to the system and don’t run back into the wall.
How to tell what an unknown wire is?
Checking your system's control board is a very reliable method for determining what an unknown wire is. The control board’s connectors typically have labels that can tell you what each wire is when other methods aren’t convenient or don’t work.
