Hi there Reginaster,
Thanks for reaching out to our community.
Sometimes, setting up a thermostat can get complicated, but don't worry, I'm here to help.
Whether you use the "Conventional" or "Heat pump" labeling to wire your Nest Thermostat depends on what type of heating/cooling equipment you have. In short, you have a conventional system if you have two pieces of dedicated equipment, a furnace for heating and an A/C for cooling. And you have a Heat pump if you only have one piece of equipment that is capable of both.
When you have a forced air system it means that your system is using fans to circulate the hot or cool air your equipment is producing throughout your home. The "G" Wire in your thermostat is the one responsible for controlling your fans, so that seems correct.
If you have a Heat pump system, you'll need to configure the O/B wire orientation. The O/B wire tells your equipment if it should heat or cool. Most systems use an "O" Wire orientation, so it should be okay.
It would be great if you could tell me the make and model of your system and show me a picture of your previous thermostat's wiring so we can set up your system so it works as expected.
If you have any other questions, make sure to let me know.
Regards,
Angel.
