Here is a unit that might do the trick... but you'd have to have two of them, one for each direction. Alternatively you could have just one to drive a relay that would turn on and off a a humidifier/de-humidifier pair. But that would leave you with a single RH level to switch on. A pair would let you switch on and off each controller at independant RH levels. http://www.tamtech.com/humitrak.htm These are somewhat less expensive then those David came across. Between 70 and 90 dollars apiece... depending on which ones you select. Cheers RicB
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