Not an effective one.
I prefer to go with Advanced Energy current research results.



wrote in message
...
Jay Stootzmann wrote:

http://www.advancedenergy.org/buildi.../crawl_spaces/

As Advance Energy showed in their field studies I think the only
alternative
to a active dehumidifier is to have a supply vent from your HVAC system
into
the crawl space [but NO return vent]

Why would you think that? A SmartVent(.net) would be another alternative.

Nick