This is usually installed in regions where extreme winter occurred. Sometimes, there is a 2nd stage heating where additional heating is provided to supplement the primary heating system. In this case the terminal Y2 is usually used. In some equipment, there is a 2nd stage cooling that helps to increase the cooling capacity of the room. Only one connection is active at any one time, that is either O or B terminal is used but not both. If the reversing valve is turned on when running heat mode, you will need to connect the reversing valve to B terminal. The O terminal is used when the system that you are using has a reversing valve (or four way valve) which is turned on when running cooling mode. Therefore, it is important the check the manufacturer’s specifications of the heat pump system that you are using before you can do a proper connection to the thermostat. However, there are instances where the reversing valve is off when running cool mode.
In most cases, the reversing valve is energized when running cool mode.
The reversing valve is a device that reverses the flow of the refrigerant in the piping system.
Single vs Double Vs Triple Pane Windows.
