What is the OB wire on a thermostat?
O, B, O/B: These wires are responsible for switching the changeover valve in a heat pump system. The O wire reverses the valve from heating to cooling, and the B wire switches the valve from cooling to heating.27-Jun-2019
What color is an OB wire?
It's usually blue, but it may also be black, brown or purple. The O or orange wire connects to your heat pump (if applicable).
How do I know if my heat pump uses O or B wire?
The heat pump is 'O' if it energizes in cooling and 'B' if it energizes on heating. Thermostats use the B terminal in systems with a reversing valve that turns on with heat mode. The system uses the O terminal if the reversing valve turns on while running cooling mode.
Where does emergency heat wire go nest?
The 'E' wire, usually but not always brown or black, goes the the emergency heat terminal on majority of thermostats, however on a nest, it should do internally.
What color is O B on thermostat?
BlueThermostat 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 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.04-Sept-2018
What does O B on cool mean?
energized in CoolingCheck your configuration. Most commonly, O/B is energized in Cooling (O on cool). For Rheem or Ruud brand heat pumps, the O/B must energize on heating (B on Heat).04-Aug-2020
What color wire is heat on heat pump?
Blue wiresBlue wires are for heat pumps. This wire connects to terminal B on your thermostat.04-Feb-2020
How do you wire a heat pump?
3:2915:52Wiring a Heat Pump Thermostat to the Air Handler and Outdoor Unit ...YouTubeStart of suggested clipEnd of suggested clipSo if you're using electric strip heating. You're going to have these jumper the aux in the ER goingMoreSo if you're using electric strip heating. You're going to have these jumper the aux in the ER going to be jumper if you have a secondary heat. Source if you did have a furnace.
What happens if you accidentally turn on emergency heat?
If you've accidentally turned on your EM heat and you're frantically Googling “how to turn off emergency heat,” don't worry. Just like turning it on, you can deactivate your emergency heat with the switch.14-Jan-2021
How do you know if your emergency heat is on?
Emergency Heat Mode Comes with a Red Indicator Light: When you turn your emergency heat on, you will see a red indicator light. This light tells you that your HVAC system is now operating in emergency mode, and it will remain on until you deactivate your emergency heat.30-Dec-2018
When should you switch to emergency heat?
Emergency heat is ideal for when the outside temperature is too cold for your heat pump to keep your home warm. If the heat pump freezes over or becomes damaged, then you should switch to emergency heat and call an HVAC service provider.08-Nov-2021
Why are my transformer wires different colors?
Furthermore, the wire colors on the transformer will be different than the thermostat wires. If you do not know what you are doing, then please call a professional. Importantly, there are a few reasons for this:#N#First, as mentioned, there is high voltage in the equipment and can be hazardous to your health.#N#Lastly, if you wire it wrong or accidentally touch the wrong wires together, you can blow the transformer.#N#Furthermore, either reason can be harmful.#N#Additional Resources#N#Also, check our thermostat category for other detailed articles on thermostats. Additionally, it includes other detailed pages about the thermostat wiring color code.#N#Thermostat Wiring Colors Code 1 First, as mentioned, there is high voltage in the equipment and can be hazardous to your health. 2 Lastly, if you wire it wrong or accidentally touch the wrong wires together, you can blow the transformer.
What is RC in HVAC?
RC – The RC terminal is designated for the power for cooling. Some HVAC systems use two transformers. A transformer for cooling and a transformer for heating. In this case, the power from the transformer in the air conditioning system would go to the thermostat terminal.
Where are thermostat wires terminated?
Remember, the wires coming from the thermostat are terminated in the HVAC equipment . Importantly, there is a high voltage inside the air handler, boiler, or other equipment where the wires terminate. Some HVAC system manufacturers provide a terminal strip board where the wiring is attached.
Is thermostat wiring color standardized?
Additionally, thermostat wiring colors are not standardized. However, these are the most wiring methods used based on my years of experience in the HVAC field, where I successfully wired a lot of thermostats and as recommended by manufacturers and common sense for thermostat wiring colors code.
What terminal is used for second stage cooling?
Finally, many systems only have a single compressor but if you have two compressors (or a two stage compressor) which should only operate off of one thermostat then you need the Y2 thermostat terminal for second stage cooling.
Where does the red wire come from on a thermostat?
The red wire should always come from the hot side of the 24-volt transformer. Additionally, the common (sometimes black) should come from the common side of the transformer.
Do you need a splice for thermostat wire pull?
Furthermore, some manufacturers put a terminal board strip near the control board in the air handler. Therefore, a splice is not needed.
What is the difference between O and B wires?
On many other thermostats, the O wire is typically connected to a terminal marked W on one side and O or O/B on the other side; the W is for use with a conventional system (furnace) while O/B is for use with a heat pump. Click to see full answer.
What color wire is used for thermostat?
Secondly, what color is C wire? Here are common uses for wire colors: Blue or Black – C – Common wire, may be unused by your existing thermostat. Enables continuous power flow from the Red wire. Red – R – 24VAC power from the furnace's transformer.
