A. No, all doors and windows should be kept shut during the drying process. Additionally the temperature of the room should be maintained at 61ºc to enable to machine to
work efficiently. Providing air movement with a fan can also help to speed up the drying process.
A. The only sure way is by checking with a damp meter, however, by checking and emptying the container on a regular basis you should see that the container is filling less and less until you are getting an acceptable level of moisture.
A. Typically, a small De-humidifier will use 0.5kw per hour, and a large De-humidifier will use approximately 1kw per hour. So it depends on how much you pay for your electricity.