I use a chemical dehumidifier and a small 150W tube heater as frost protection. This combination reduces the worst of the rust caused by humidity in the workshop.
Attachment 41132
My workshop is quite small and so I don't really have room for an electrical dehumidifier, but I have just been sent an idea/build for a control system that estimates the dewpoint and from this can switch two electrical devices, eg heater and dehumidifier.
Attachment 41133
