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.
Is my heat pump O or B?
O stands for orange and B for dark blue. The O and B terminals are for heat pumps; the B terminal is used in conjunction with Rheem, Ruud, or any other manufacturer that energizes the reversing valve in the heat pump’s heating mode.
Is B common on Trane?
On a Trane system the common wire is designated as B. The white plug with six wires at the top right of your first photo (and the attached photo) contain the 24V red wire and the 24V blue wire (common). If you set your multimeter to volts AC you should get a reading of 24VAC between them.
What color is the B wire on a thermostat?
Blue
Thermostat Wiring Color Code Chart
| Marking | Wire Color Code | Description |
|---|---|---|
| O | Orange | Change-over relay to cool relay |
| B | Blue | Change-over relay to heat relay |
| A | Heat and cool active to any relay | |
| L | Emergency heat active lamp |
What do thermostat letters mean?
Y = yellow, g = green, r=red, w = white. Generally the red is your “hot” wire, straight from transformer that supplies constant power to your thermostat, which when each function, ie, cool, or heat is engaged, allows connection between red and whichever wire is called for by the thermostat.
What is a reversing valve o B?
The O/B terminal is for heat pump systems and is used for the reversing valve. When the “O” option/position is selected the reversing valve defaults to the heating mode. If you get it reversed the heat pump will cool in the heat mode, and heat in the cool mode.
How do I know if my wire is O or B?
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 does raindrop mean on AC?
dry mode
For air conditioners that have dehumidification systems, clients may see a water droplet icon on the thermostat screen. Usually, what this symbol means is that the air conditioner is running in dry mode to remove excess moisture from the air.
What does the W / B Terminal on a thermostat do?
W/B: The W/B terminal controls the heat relay or valve. When the thermostat calls for heat, a signal is sent to power up the furnace and the blower fan or the boiler, heating your home.
Where is the C terminal on a furnace?
In this example diagram, you can see that one leg of the secondary connects to the R terminal on the control board, and the other leg connects to the C terminal. In this example there’s actually a C terminal present, but that will not always be the case (especially in old models).
What’s the difference between Y1 and W / B terminals?
W/B: The W/B terminal controls the heat relay or valve. When the thermostat calls for heat, a signal is sent to power up the furnace and the blower fan or the boiler, heating your home. Y1: The Y1 terminal is used for the compressor contact in a single-stage heat pump installation.
What’s the connection between a thermostat and a furnace?
Between the thermostat and the heating or cooling equipment is a set of low-voltage wires that are run from the thermostat control terminals to the terminal screws on the furnace or air conditioner control terminal strip.
