If you're just trying to sense water, Glentronics has a water sensor model #
BWD-HWA 'Basement Watchman'. It's 9VDC, solid state, with a 100 dB alarm.
Don't remember where I got mine. May have been Grainger.
http://www.glentronics.com/water_alarm.htm

"peter" wrote in message
news:yeWvf.374$Xo5.100@trnddc02...
wrote in message
...
I need to monitor the humidity in the crawl space under my house.
Radio Shack has a unit that you mount inside your house and then place
a remote sensor in the crawl space. Has anyone had experience with
this unit? Can anyone recommend a better uni?. I like the idea of
being able to monitor the humidity inside my house without having to
go into the crawl space.

Aha! I was just thinking of doing the same myself to detect when the
crawlspace is flooded. There is indeed a remote sensing hygrometer set
selling for around $26+shipping mail order. Search for RMR603HGA with
froogle. But do your own research. It may or may not fit your needs.

I also did an experiment with a non-remote sensing digital hygrometer. I
hung it inside the crawlspace access panel. When the crawlspace is
normally
dry, it reads about 50%, same as outside. When the crawlspace is wet with
puddles, it reads 75%.