I've been trying to find a built-in dehumidification system for when we finish the basement and looked into Humidex with interest. But then I read this:

"Once the moist air is drawn into the powerful, quiet patented Humidex system, it is then expelled to outside of the house through a 6" dedicated duct. This flushed-out, contaminated air is then replaced with a flow of relatively drier, warmer and fresher air drawn downward from the upper levels. The warmer air will lower the relative humidity and reduce the condensation on the basement surface.

The interior upstairs air is then replaced with cleaner, fresher outdoor air entering the home naturally via windows, doors, and cracks."

It removes the basment air and then pulls air from the upper levels and outside to replace the expelled air. I don't see this working. We have about a 1/4" gap below out basement door. How much air can possibly be drawn under that? Plus, their method assumes you have a leaky house. Our house is very tight. If the system tries drawing air from outside it will end up drawing it (in reverse) through my kitchen vent. There is nowhere else to draw it from (we don't leave windows open, but even if we did, the humidity level is pretty high outside in the summer).

What I'm looking for is basically a built-in humidifier that will extend into the finished part of the basement and will pipe the pulled moisture either outside or (in our case) dump it in the sump (our sump has a gravity drain that flows slightly all year).