I used to do what all of you did when you decided to replace your HVAC units.
Right now, I just went through a major remodel of my house, and while I was remodeling my house, I also decided to get rid of the HVAC units in my house.
I had an extremely old furnace and an extremely old central air conditioner. Sure, these HVAC units were still working, but I knew that it was only a matter of time before I would end up needing to replace the HVAC units anyways. I figured that since my house was being torn apart anyways, I would benefit from replacing the HVAC units immediately. I called an HVAC company, and I arranged a time to be able to have my new furnace and central air conditioner installed. When the HVAC company got to my house, they assumed that they would be taking my old HVAC units with them. Like I said before, I used to do that. When I would get a new HVAC unit, I would have the HVAC technicians take my old HVAC unit. However, I learned that you could actually sell your old HVAC unit. There are people that know how to fix and replace HVAC units, and you can sell those. HVAC companies usually fix these HVAC units, sell the parts, or scrap the metal for money. Instead of letting the HVAC company benefit for no reason, I decided to go through the process myself. Sure, it took some work, but I made some money that can pay back some of the cost of purchasing my HVAC units in the first place.