Yeah - get a new hygrometer, one that is accurate. I live in a "Semi-desert" area, in the "Inland Empire" of Southern California (more or less, between Riverside and Palm Springs). Our climate is usually pretty dry, the relative humidity normally hangs at around 20% or (quite a bit) less. I have seen it get down to the "lower single digits" - but never zero!
Try to incorporate some type of "Swamp Cooler" into your system. It's a "Win-win-win Situation":
1. The "thing" is designed to work on the principle of evaporating water, thereby raising the humidity.
2. The lower the "ambiant" humidity - the more efficiently the thing works, providing lots of cooling power to your fresh air intake.
3. The basic replacement parts are pretty cheap and readily available in areas with low humidity.
Making something that will work is simpler than it sounds. Just Google "Swamp Coolers" and spend an hour or two reading up.
