GeorgeK-NJ wrote:
By reducing the number of vents you are reducing the air movement under the house, but still letting it ventilate and reduce any condensation.
Although it isn't recommended in the colder areas of the country, I leave all of my vents open year round. I live near the coast and the temperatures aren't that bad in the winter as a rule. Unfortunately, what's good for keeping cold air out for obvious heat loss reasons, isn't necessarily good for moisture control.
I learned this lesson the hard way a few years ago when I lived in area even nearer to the water and closer to sea level. I was having a moisture problem under the house, and you wouldn't believe some of the things the pest/moisture control companies were recommending.
I called our local extension agent for recommendations since he shouldn't be influenced by any desire to sell anything. He recommended putting a fan in the crawl space access opening to help out with the ventilation. I did that and I learned quickly what I should have already known since I had worked in air conditioning in a former life. I turned my crawl space into a giant dehumidifier. The problem was that I was trying to dehumidify the whole county under my house. I was moving warm, moist air through my crawl space where it was being condensed on all the cool surfaces. In about a week, I had standing water under my house!
Again, although I'm not necessarily recommending this, it would seem that colder weather can be a better time to leave the vents open.....if your area isn't too far up nawth.
