So the sellers weren't willing to deal on the house with the natural gas fired A/C, so I kept looking. Today I looked at another house with a wacky HVAC system. The guy that built it and lived there was an engineer....
House has a forced air system, 2 coils in the attic, and a ton of plumbing and ductwork. Seems to be a 4 pipe system (looked like about an 80 pipe system), 2 for cold water, 2 for hot.
For heating, there's an old (1959) Weil McLain boiler (I think its nat gas, but the neighbor said it was oil) for heat, expansion tank, pump, the whole 9 yards. Funny thing is, there's a run of the mill water heater sitting next to it for the domestic hot water.
For cooling, I'm not quite sure what's going on, but on top of the garage there's a big aluminum thing (solar collector for the A/C system according to the neighbor) with copper pipes running into the house. In the mechanical room, there's a heat exchanger to chill the water loop. There's also a wooden enclosure with several lines running in/out of it, and it sounds like there's a compressor in there....there's also what appears to be a TXV near the heat exchanger.
Does this sound like a solar system? Do they have compressors?