I thought this might be cool. I will describe two HVAC related things without too much detail. I wanted to see if anybody here has an idea of what they are? One should be fairly easy and the other a little more difficult. Old guys, bite your tongues for a bit and lets see if the younger ones can figure it out.

1. A situation that mostly occured outdoors where an attempt was made to join two dis-similar metals to handle high pressure. It was a colossal failure and cost the offending company millions.

2. A system that used no orifice or expansion valve but worked beautifully.