hello! i moved into a home w a geothermal heat pump. I was super excited, but then it turned out it had MAJOR issues and will be way too expensive to fix. so, we need a new unit. i know nothing, so please forgive all of the questions. what exactly is an HVAC and how is it different from all the other a/c stuff that's out there? Or are they all HVACs? Also, i am looking around and i know about american standard, lennox, rheem, and trane. Please let me know if there are others that are better, or if any of these is not great. i am interested in an energy star rated unit (would like the tax credit), i need it to both heat and cool, and i would like the option to install an air cleaning system later (i know trane has that, do others?). i live in hammond, la my house is about 3,000 sq feet, 1 1/2 stories. if anyone has any recommendations or information, I would greatly appreciate it!