What is Nest Heat Pump Orientation O or B? [A Switch]

Nest heat pump orientation is a setting on a nest thermostat that is used to set cooling and heating of a heat pump system between O and B. This makes it possible for the heat pump system to heat your home during the heating season and cool it in the cooling season.

The orientation setting O/B energizes the reversing valve. When energized, the reversing valve helps the heat pump to switch between the cooling and the heating modes

What is a reversing valve?

A reversing valve is a small device on a heat pump system that moves between two positions depending on the OB settings on your thermostat.

On one position

It switches the direction of the flow of the refrigerant so that in one direction, the outdoor coil will act as the condenser coil with the indoor coil acting as the evaporator coil. This helps the heat pump to work as an air conditioner.

One the 2nd position

It will change the direction of the flow of the refrigerant into the opposite direction. In this position the outdoor coil will act as the evaporator and the indoor as the condenser and this will make it possible for the heat pump to heat a home or building.

How to set heat pump orientation on a nest thermostat

Setting an appropriate heat pump orientation is important because it will determine what air will blow out of vents. When set O, on default the heat pump should blow hot air and when set to B it should blow cold air.

If cooling and heating on your nest thermostat is reversed, then you need to correctly set the orientation settings to fix this problem. Depending on your Nest thermostat model, here is how to set the orientations;

For Nest thermostat

Open the Home app Google Home app.
Tap your thermostat.
At the top right, tap Settings .
Select Thermostat.
Scroll until you find Heat pump. It should show which wire configuration is currently selected.
If the O option is highlighted, select B.
If the B option is highlighted, select O.

For Nest Learning Thermostat and Thermostat E

On your thermostat, go to Settings Nest settings icon.
Select Equipment.
Select Continue and then Continue.
Select Heat Pump.
The Nest Thermostat defaults to an O setting for heat pumps.
If the O option is highlighted, select B.
If the B option is highlighted, select O.
To make sure the issue is resolved, test your heating and cooling again.

What is the O/B wire on a Nest thermostat

If you removed the thermostat display from your thermostat, you may notice that there is a terminal labeled O/B on your thermostat and a wire as well. This simply means that your system is a heat pump and it can switch modes between cooling and heating.

If you can’t see the O/B wire or terminal, chances are, you don’t have a heat pump but a conventional system. which consists of a furnace and an air conditioner.

Final thoughts

To wrap it up, Nest heat pump orientation settings help you to set cooling and heating modes appropriately. It controls the reversing valve, a device in the condenser unit that reverses the flow of the refrigerant making it possible for the heat pump to cool and heat when needed.