I am a Chocolate Chef (Chocolatier) professionally, and temperature and humidity is vitally important to my product turning out. We purchased this item in hopes of the helping to locate humid spots in our production kitchen and found that this meter was perfect for that.
The probe is fantastic and incredibly accurate, and the meter refreshes at an incredible rate. We ended up buying two more for the retail area, and the storage area. Fantastic product!
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I already have a nice synthetic material dial hygrometer and decided to try a digital hygrometer and purchased the Extech 445815 after a lengthy research on the subject. I like the price for performance the wired sensor and dew point display features most desktop/wall hygrometers don't have.
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with this meter and a dehumidifer can now control mold, no more guessing. very happy with product.
Honest reviews on Extech 445815 Humidity Meter with Alarm and Remote Probe
I am disappointed to find that the calibration on this product is ineffective. The "pot" (potentiometer) for humidity adjustment can be continuously turned either clockwise or counter-clockwise. There are no stops in either direction. With each full turn, a very quiet click is heard, which is also worrisome. So it is impossible to tell when it is maximally or minimally adjusted.
I used a calibration kit (http://www.amazon.com/gp/product/B000A3UBLA/ref=oss_product) to test this item. Half-turns of the pot, and adjustment periods of 12 hours after each half-turn, produced readings of between 71% and 73%. I could never get it to read 75.5%, as it should have.
Granted, the calibration kit made testing the item difficult. The plastic bag in which it comes is too small to hold the entire item. So I put the probe into the bag, sealed it as well as I could, and then put the item plus the kit's plastic bag all into another, larger plastic bag and sealed that completely. I allowed longer adjustment periods because of this departure from the recommended procedure. (I feel the adjustment periods suggested by the calibration kit -24-26 hours -are unnecessarily long, given how quickly this monitor responds to change.)
Extech makes its own calibrators, which don't require these machinations, but they are absurdly expensive. The use of another maker's calibration kit may throw off readings, but it doesn't change the fact that this monitor cannot be reliably adjusted.
The manufacturer's technical service person was not helpful. He acknowledged that the pot has no stops but insisted it is effective anyway. That is not my finding. I am keeping the item but using it with the knowledge that it is 2-3 percentage points low, at least in the low-70s range.
If anyone knows of a monitor that is *accurate,* I would appreciate hearing about it. (Any response to this posting will trigger an alert to me.)
Also, not that it matters, the unit I received is black and silver, with no green pieces as illustrated on this page.
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I have bought 4 of these from Amazon. I have calibrated all four for temperature accuracy and they all consistently read the same within acceptable limits. However, with one of the units I cannot adjust the relative humidity. I cannot correct the humidity reading with the adjustment. The dew point reading depends upon the accuracy of the relative humidity and so the dew point is in error. I need a good dew point reading to prevent mold in some air handling equipment so this unit forces me to guess on its error and estimate the dew point. Not a good feeling. Some people might think three out of four is not bad but I don't see why I have to put up with the time and trouble caused by poorly manufactured and tested products! One star, less if I could!
