Stretch wrote:

Try this link to a humidity control article:

http://www.contractingbusiness.com/C...S=&NI L=false

OK. Try looking at Smart Vent's 12/19/2000 US patent no. 6,161,763
"Module-controlled building drying system and process" at
http://www.freepatentsonline.com.

It describes "...drying air circulation between inside and outside the
building based on absolute humidity and temperature sensor measurements"
and claims "a programmed controller... the input ports are connected to...
outside absolute humidity sensors... [and] inside absolute humidity sensors
[and] the output ports are connected to... [a fan system.] ...if the outside
air has a lower absolute humidity than the inside air... the fan system
output will be activated... if the outside air has a higher absolute
humidity than the inside air... the fan system will be shut down."

Nick