Ducting Systems and Air Ventilation - Whole House Fan and Mini Duct AC

I have a mini-duct air conditioning system, which can be used without the air being on to circulate air throughout the house. It is set all year long to intermittently come on to move air around. This is not the same thing as a whole house fan, is it? And could my house benefit from installing a whole house fan? I'd like to use the air conditioning as little as possible.

A separate, but related question is, can I install a powerful bathroom fan that would serve the same purpose as a whole house fan? I'm in a two-story, approx. 2000 sq ft rowhome, which has a partial attic -- 1/4 to 1/3 of the total roof area. But most of the roof is flat with no attic space below.

Any insight will be greatly appreciated! Thanks.

A bath fan will never be able to pull as much air as even a small whole house fan. Whole house fans are installed so as to pull outside air in through open windows and doors, then exhaust it through the attic to the exterior through vents on the roof.

I've been in a few houses that had them, and they were nice if the humidity wasn't too high and the exterior temp dropped low enough at night. DC normally has pretty high humidity doesn't it?

Yeah, it is usually pretty humid in the summer -- she says, dripping with sweat from just mowing the lawn.

And I am right in assuming that circulating the air through my mini-duct system is not the same thing as a whole house fan, right? They don't really perform the same function?

nope what you have now is just circulating the air..might help equalize temps throughout and possibly you'd feel a bit cooler from the air movement..but since you aren't drawing in outside air..not the same.