Extech 445715 Digit Thermometer

I just installed a whole house dehumidification system in my home and needed 2 hygrometers for the main floor and the basement. I wanted to buy an accurate unit with a large print digital display. Thus far, the temperature tracks right on target with my expensive furnace thermostat. I have nothing to check the accuracy of the humidity readings, but assuming they are fairly accurate, I was able to adjust my Aprilaire humidity setting to keep the humidity levels at ~ 50% in both locations. The unit has a fold up stand on the back of it so I did not choose to wall mount them. I placed one of them on a book case shelf in my great room and one on my office desk in the basement. I also like the mount of the sensor on the outside of the unit which produces a more accurate humidity reading. I have used the Extech units for 1 month, but I am extremely satisfied with their performance to-date. They are more expensive than many others, but always believe that most of the time you get what you pay for by spending a little more money. In this case, I am protecting my entire home against humidity damage and was willing to pay more for a quality product. As usual, Amazon's pricing was better than the competition for this product. I can't testify that there wasn't a better price out there, but the price was good and Amazon's excellent shipping policy for Prime customers made the decision easy.

Dew point display was the feature that made me buy this product. It has worked well, has a long battery life, and is accurate. The dew point shows how much humidity I can safely add in the winter without condensation forming on the windows. It also indicates the efficiency of the air conditioner in the summer. "Delta T" (the change in temperature, the temperature of the intake air minus the temperature of the chilled air) shows how much heat the air conditioner is removing. Since the a/c also removes moisture, the dew point tends to be the same as the evaporator plates, which is the temperature of the chilled air. (Unless you live in a dry climate.) So, just noting the difference between the ambient air and dew point indicates the efficiency. It is amazing how much more efficient the a/c is in the morning, when the outside temperature is in the 70s versus how little chilling happens in the afternoon in the 90s. I quit running the a/c in the mid afternoon, and save a few buck on the electricity. It is a fine product. Spread the word about the dew point!

Out of the box the unit would not power up (or perhaps just the display simply would not power up). After replacing the battery, which I thought must be DOA, I discovered that the display powered up after pressure was applied near the battery compartment. Upon further troubleshooting, the sweet (dead) spot turned out to be an area on the left size of the bezel just below where the probe is mounted. Applying very slight pressure at this point shut the unit down. (Again, it could be just the display losing power.) I could get the unit to stay on, but the slightest touch to the left bezel again shut it down.I don't object to overpriced Chinese-made goods--it's today's reality--I do object, though, to sloppy quality assurance. (Neither the shipping box nor the unit packaging showed any signs of distress, by the way.)Thanks to Amazon's no-hassle return policy, this unit is being sent back. Since I'm desperate for a hygo-thermometer that is easy to read, I ordered a replacement unit. I'll give it another try.Update 2015-03-08: The replacement unit from Amazon powered up without issue. In comparing the temperature reading to three other hygro-thermometers, it was within 1 degree. The humidity reading is within 4 percent of my other units, which is within tolerance. The unit responds very quickly to temperature changes. After three weeks in my wine cabinet, I am satisfied with the performance.Further, I'm impressed that a rep from Extech Instruments offered to assist. (See comment to original post.) The value of good customer support cannot be overstated. I've changed my rating from 1 to 4. Keeping me from rating a 5: Value. At a Chinese labor rate of about $2.50/hour, I expect a better price.

I am editing this review from 1 to 5 stars. The original unit was defective so I contacted the seller and the customer service they provided was perfect. They provided a second unit within a week. It is rare to have the ability to personally contact a vendor and to have no-nonsense service...very professional and they stand by their product. For this reason, they get a 5-star review!!Original review: Extremely disappointed. I purchased the Extech Model 445815 standard configuration with the attached probe. A feature that lured me in was that this unit was able to be calibrated. I looked at the NIST traceable options as I would like a somewhat accurate reading of RH in any meter I am choosing. However at either $130 or $173, the price is certainly prohibitive for this level of hygrometer.Using the Boveda One-Step calibration standard of 75% RH, I followed those instructions to the letter. The Extech never registered above 56%. No problem I thought, I will adjust the calibration bucket and line the display up with the calibration value. To my surprise, and as noted in other negative reviews, the calibration bucket did nothing at all...no change in value with 1/2 turn...after several minutes, another half turn and still nothing. Rinse and repeat. Bottom line is the RH calibration does nothing. I was able to calibrate the Temperature and that adjustment screw worked.My experience indicates to me that this is very poor quality toy with ornamental features at best. Save your money on this one folks as you will be disappointed. If you need accuracy, you will need to step up to a scientific-level meter at much higher cost point...This unit is NOT the answer.

This is a very good instrument displaying exactly what is relevant: Relative humidity, temperature and dewpoint. The dewpoint calculated from the other two is very useful to know but most other instruments show the time instead and who wants that on an instrument like this? The alarm functions and the max high and low recordings are useful as well. Designed by a respected instrument manufacturer by engineers with a vision.I lost my old one and had to find an exact match since nothing else could serve my needs any better.

Instructions for the product are not available in English nor in French. Only in "Chinese" Not really useful.

Good but very overpriced

- Calibrated using Boveda- Well-built and BIG digital display...readings can be seen clearly from far away!- ACCURATE and FAST response time, almost INSTANT actually!- TEMPERATURE & RH% readings are very useful in any environment, but it does DEW Point readings as well...which is a BIG plus!- Probe can be detached to take readings behind walls if necessary, which is super convenient & handy- MIN & MAX can be reset, but can also be used to trigger a beeping ALARM which is more useful than it seems- This product only PROVES that EXTECH's already excellent reputation in this industry is WELL-DESERVED and 100% JUSTIFIED- Cheap analog meters do not guarantee fast, accurate & reliable readings...so stop wasting your time and invest in a good HIGH-QUALITY tool like THIS one and say bye bye to those analog meters for good!

Il prodotto mi è arrivato nei tempi previsti, amazon è impeccabile.Lo ho testato con termo igrometro professionale (250 € la sola sonda con compensazione barometrica) e ho visto che è arrivato tarato alla perfezione, non è stato necessario intervenire.Il funzionamento è molto semplice.Per questo prezzo è davvero un ottimo prodotto, potete settare allarme della U.R. al valore desiderato, unico allarme è sulla umidità !Ottimo davvero.Utile per capire quando è ora di aprire le finestre.