> Greg, I don't want to turn the subject of this BB away from strip built
> boats and toward "ventilation and humidity control" (I apologize
> in advance to the owners of this BB), but I want to dispell some
> well-intentioned misconceptions people sometimes have. I have been
> designing industrial air conditioning, ventilation, and dust collection
> systems for many years as a mechanical engineer.

> What you describe is a ventilation system. It doesn't remove humidity from
> air, it just replaces the air in the basement with air from somewhere
> else. The air you exhaust has to be "made up" from outdoors. It
> could come from upstairs, but that air will also have to be replaced, and
> the only place left is outside. Air will take the path of least
> resistance, seeping in through cracks to the outside, so on hot humid days
> you will just be bringing in hot humid air. On nice dry days this may be
> an improvement over the air that you exhausted, but in the climates
> typical of Minnesota and much of central and eastern Canada you will still
> have a damp, musty basement much of the rest of the time. In the winter
> you will bring in cold, unheated air that your furnace must then heat. If
> you have very tight construction, chances are that little fan will just be
> whirring along moving very little air. Propeller-type fans don't have the
> ability to move air against much resistance, such as pulling air through
> little cracks, so they just respond by moving less air while spinning at
> about the same speed. You need to have some good size openings to the
> outdoors to let air in. The same ideas about make-up air apply if you have
> a dust collection system that exhausts outdoors. However, even though dust
> collector fans are not propeller fans and have much greater ability to
> move air against high resistance, you may see an improvment in such a dust
> collection system if you provide a source of makeup air. This only applies
> if your dust collection system exhausts outdoors.

> If you have a damp, musty basement, you will need a dehumidifier. So for
> about $300 canadian you could get one to create a very nice environment in
> your basement. By the way, don't run your ventilation system while your
> dehumidifier is operating, because you will be bringing in lots of humid
> air, and the dehumidifier probably won't be able to keep up. If your
> basement is not damp and musty, then a ventilation system will be just
> fine. You don't need the expensive humidity controller in this case.

> Hope this helps.

> Paul Jacobson

It sure does, Perhaps teh commercial version has an import duct also, I could see paying that price for such a simple device adn I didn't really get into actuall checking the humidity in my basement let alone any differential. I figure, glass before the humidity becomes a factor to worry about. Not an option for all. Thanks for the info though Paul.

Greg