Hi Everyone - Great site with a TON of useful information. I've been reading thru the forums a lot as I'm trying to gain basic HVAC knowledge since my wife and I are looking for our first home. Today, we toured a gorgeous bi-level home and I had never seen the HVAC system so I figured I would post some pics and would like to know A. How it works and B. It this better or worse than more conventional systems i.e. GFA The house has central air and baseboard heat for the ground floor (and lower level). However, the upper floor with the bedrooms has vents in each room and a giant metal fan unit in the hallway that opens up when you turn an old fashioned timer. I know that the hallway fan vents air thru the attic which I can see would helping in the summer since heat rises and the rooms can get pretty warm, but I'm wondering if during the winter - does heat from the furnace actually get circulated in thru the air vents in the bedrooms, or is it just circulating air from the downstairs and bringing it up? I did notice that in the bathroom on the same floor was a large foiled cylinder, but I have no clue what it does!!