I have a dehumidifier in the corner of my garage. It is on permanently and switches on and off periodically. It takes about 5 litres a week out of the air. It feeds into a sealed plastic barrel. Nothing rusts in the garage.

Mine is an Ebac Humidex something. Like this:

http://farm2.static.flickr.com/1057/...8b0dec9a_m.jpg

I've had one for eight years and it eventually stopped working so I bought a new one recently for around a hundred quid.

Charlie