Extech 445814 Humidity Alert Hygro-Thermometer with Dew Point

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!

Very accurate readings. Matches my de-humidifier within 1 or 2 degrees. If you have problems with humidity this gadget was recommended to me by my hardwood flooring company to monitor "buckling" in the floor boards. Works great.

It provides what says, temp and humidity, of course I have nothing to compare it to. It does rise and fall with the use of showers, so I guess it is working. Temp guage compared to another one six inches away is one degree different, but again which one isn't right???? Okay, I paid $46.00 I keep thinking you could have found one cheaper and then I paid shipping. I haven't used the alarm mode since it never goes over 70% and usually stays above 50%. The unit was easy to step up, batteries went in like a charm and it displays nice large number so even with your glasses off you can read it. Good luck.

Helpful for keeping tabs on condition of my house

I live in Sao Paulo, Brazil , and wanted a third themometer/higrometer to monitor temperature and humidity in my apartment. The higrometer doesn't match the readings of the other two, the difference being more than 10 percentual points. The so called " humidity calibration adjust" doesn't work. Then after two weeks suddenly the temperature reading jumped to a fixed value of 80 degrees Celsius (same as 176 degrees Farenheit). I tried the "temperature calibration adjust" that also is a fake: it doesn't work. Pity: the product is good looking but the quality is not built in it. I am very disappointed by the purchasing of this product. I had to give one star rating just because ZERO is not accepted by the system.

Some great and some not so great reviews on this, so I took the plunge hoping to get a good one. I didn't. The temperature was almost 3 degrees high so could not check the RH accuracy yet. I had read reviews finding the calibration pots don't work. Anyway I tried the temperature pot, didn't seem to work at first. They say wait an hour which seems odd since a calibration change normally shows up quickly. I had a fan blowing a breeze over this and my reference Amprobe thermo-hygrometer meter. Didn't see much happening even after half an hour, finally turned the temp pot all the way counterclockwise to where it felt loose. Checked back later and it was now about one degree high. There it stayed so the best I could get. The RH was slightly low even after mentally adding in the 2.5% for the temperature being a degree high. Had this pot at maximum, the RH went up a bit, maybe 2%. Now I have an instrument that's almost accurate. That's actually pretty frustrating since you spent money, spent time trying to calibrate it, and you want it to be correct. Couldn't do that here so wasted my money. All they needed to do was give the calibration pot more range and problem solved. Especially since it came from factory 3 degrees off, more than could be corrected. One of those times where you shake your head and say, Really? If I had seen the one with the remote probe with the same 3 features I would have purchased that instead, but unfortunately did not see that until after I got this one. This unit suffers from slow temperature response like all these similar instruments with the temperature sensor in the case. The humidity will respond faster than the temperature which also gives these instruments errors. Great looking instrument with the important dewpoint reading, but fails at accuracy which makes it of dubious value.

This unit has worked well for years providing accurate humidity, temperature, and dew point. Easy to setup, easy to read.

Performed as expected, batteries last along time.

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

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.

Vielleicht hatte ich Pech mit einer Retourware: Die Blisterverpackung war wiederverschlossen, die Anleitung fehlte (gab's aber im Internet). Ich wollte das Instrument kalibrieren, doch bewirkte das Drehen an den Schrauben (wenigestens für die Feuchte) rein gar nichts. Trotzdem ist die Anzeige für den Taupunkt im Wohnbereich hinreichend genau (~1degC). Sonst funktioniert am Gerät alles. Die Anzeige ist sehr gut lesbar und groß. Es ist eines von nur 2 vergleichbaren Geräten, die den Taupunkt anzeigen, welche ich online finden konnte (das andere um ~EUR 15 empfehle ich nicht).

... was soll ich sonst noch sagen. Frische Batterien eingelegt, für einen Bruchteil einer Sekunde zeigt sich das Display im Testlauf (alle LCD-Anzeigen werden klar und deutlich dargestellt) - dann nur noch hauchdünne und kaum sichtbare Darstellung der Werte. Diese sind so schlecht zu sehen, dass ich noch nicht einmal feststellen kann, ob die Werte korrekt sind. Ich werde versuchen eine Garantie geltend zu machen.