small fan will do, for your house.
On 01-03-2007, at 3:19PM, you wrote, "I want a very powerful vent that doesn't leave any moisture in this bathroom. Any ideas how to tell how powerful a vent is?"
It's a small house, in a cold climate. What you REALLY want in a small bathroom in a small house is not a big fan. You want a fan with a small motor, with easy access to the vent opening so you can manually close the vent whenever you might want to. The smaller the fan, the more likely it is that its design will be quiet by nature, and the manufacturer's claim about noise (or low-noise) will be accurate. The quieter it is, the more people enjoy leaving it on.
When you buy a fan, its capacity is written on the box. That is how you tell how powerful a vent is.
The cost can vary by a factor of ten. $20 to $200. In one bathrooom I spent $200 for a remote squirrel cage and a closeable vent opening, and $100 for a small ultraquiet (but not squirrel cage) fan in the other bathroom. I know I could have spent less than that, but I really wanted peace and quiet, not the whirring noise of "functional" motors that "do the job".
i also want a quieter computer, so i'm getting an iMac. :)