Hi all, I recently bought a house that has a Geothermal system that was installed in 1998 (when it was first built), that came with no manuals or any type of documentation that I can find, and let me tell you, it's a been a crash course in HVAC learning compared to my old "normal" electric AC and gas furnace. While trying to familiarize myself with my system (something I like to do BEFORE something goes wrong, so that I don't get seen as an easy mark by repairmen) I've come into some questions. 1. Is a Geothermal system and "heat pump system" the same thing? Are there any other HVAC systems that use heat pumps? 2. What is the difference between the a closed loop and an open loop system? 3. I'm assuming the reason that coolant is used most of the time instead of just water is because in places like where I live (South Dakota), water could freeze and rupture pipes? Is that correct or is there a different reason? 4. I think I'm correct that all Geothermal units are "ground source" (meaning that they take heat or cooling from underground) However, how can I tell if I have a "direct exchange" (it just pumps coolant around thru the ground) or a "water source" (it pumps water down into pipes interwoven with the coolant pipes) system? (If I'm wrong with any of my definitions, PLEASE let me know) 5. If a certain manufacturing company has their logo emblazoned on the large metal box in the basement (in my case, FHP Energy Systems), does this mean they probably made the whole system, including the box (I think it may be called a cabinet), the pipes to the underground, and the heat pump? Or is it normal to piecemeal system parts out to whomever installers/contractors can get the best deal from? 6. My serial number on the sticker on the side of the metal box thing in my basement says "FHP Manufacturing Division", and has a serial number that starts with an EJ ... I know it's manufacture date is in 1998 because of this page - https://www.building-center.org/florida-heat-pump-hvac-age/ - However, it has the a model # of GT026-1VTN, as well as a model # of HP100-1XS (on a different sticker) - Which one is the model number for which part? 7. I think I have R-22 refrigerant/coolant running thru the pipes of my system, I know that they recently outlawed the production of NEW R-22, and that eventually I'll have to flush all the old stuff out and replace it with an alternate coolant. Does anyone know how to tell how many gallons of coolant are in your system? and/or approx. how much it will cost to have it replaced eventually? Thanks for this site, and for all the information it provides.