Product review (2 stars): Great temperature probe, horrible humidity probe
Man oh MAN do I wish these worked fully!

The Everspring Z-wave wireless temperature humidity sensor is built like a tank.  It has some serious heft behind it; feels like you stacked three hockey pucks in your hand.  The buttons feel really good, and the display is large and easy to read from the right angle.  (Pretty much you have to be looking down on the unit from above, so if it's mounted higher than your eyes you're not going to see anything.)

The temperature function was dead on with both units I received.  Actually the temperature resolution was better than I can normally measure without breaking out a thermocouple, and I just didn't care that much.  In other words, well under 1F degree of accuracy, which is great!...

...but the relative humidity readings on these are *absolutely BONKERS!*  There's a well known test called the salt test (google it) where you make a known solution of salt and water, then stick your measuring device (or devices) into an air sealed environment with the salt solution for 24 hours, and they should read 75% RH.  (Cigar afficianados swear by this test to calibrate the hygrometers for their humidors, apparently.)  I figure if it's a test the cigar guys swear by for things that will be ruined by too much or too little humidity, then it has to be a reliable test.  So I ran a salt test on one of these, and included in the bag my non-zwave hygrometer for reference.  After 24 hours, my hygrometer was reading 74% RH (not bad!), while the everspring was reading 90% RH (the maximum value)!!  So I took out the salt pack and threw in some dessicant packs and came back after another 24 hours, my non-zwave hygrometer was reading about 30% RH while the everspring was reading almost 60% RH!

So I contacted The Smartest House and they were >>>extremely<<< gracious and easy to work with -- sixteen million stars for The Smartest House, and they shipped me another unit.  Unfortunately the second unit tested near identically to the first one with the salt test, completely pegging at maximum RH% when it should only be reading 75% RH.

So while I really *really* wanted to like this unit, I can't keep it nor can I recommend it.  At $40, it makes one heck of an expensive temperature probe since the RH% implementation is completely broken on the two units I received.  And since other units (passive infrared from monoprice) do temperature just as well, it makes no sense to keep this one around at all.

On the bright side, it integrates easily with a Vera Edge, but with broken RH% it's all for naught.  Pity, I really WANTED to like these and buy a few of them!