Tom,

I owned a house with the same situation. There was a room under the front porch which was a poured concrete slab. It too had a door to separate it from the main basement area and had no ventilation. When the house was built, the selling feature of this was that it was a "cold cellar"...good for keeping fruits, preserves and the like. Me personaly, I kept my beer and wine in there. Anyway, to answer your question, I had no problems with condensation or dampness.

Thanks!

How hot does it get where you are in the summer? That would probably be a factor.

Tom,

It didn't get hot there in the summer. I don't know if this is your first house with a basement but it will always be cool down there. Even with A/C in the house, on really hot humid days my basement is my refuge

Tom,

I din't read your question correctly as to how hot it gets where I am. I am in Ontario, Canada (Toronto Suburb) and it can get pretty hot and humid...well up into the 90's and my basement is always cool and dry.

The best and cheapest appliance to remove basement humidity and mold is the Breeze. It works on the same principle as other systems (Wave Ventilation, EZ Breathe, and Humidex), just costs more than a thousand dollars less: only $299. And, it carries a 5 year warranty. Why would anyone pay over $1,500 for the same thing or recreate the wheel by trying to make one yourself when you can buy a professionally made one at that price? I have it in my basement and it works like a dream using the same principle employed in the expensive units. It costs about $12 a year to run continuously. Check it out: BreezeSystemsInternational.com or at Amazon or Ebay.

The best and cheapest appliance to remove basement humidity and mold is the Breeze a dehumidifer.

All regards to vendors of the fan in a box, but the building scientists at Building Science Corp. recommend dehumidifiers. You pick the brand.