Extech 445814 Humidity Alert Hygro-Thermometer with Dew Point - Digital Indoor Humidity Monitor, Programmable Visual and Audible Alarms, Min/Max Memory, Wall Mount or Desktop Stand

I am glad I purchased this humidity & temperature indicator before I purchased a humidifier. I found out that I did not need a humidifier ( found out the bedroom is 45% to 50% RH ). The unit is well made, does not run through batteries, & I am happy with it.

I set mine up for my T room. With the nice large LCD readout at a quick glance I can see what each enclosure's humidity and temperature is. I don't use the alarm features since I have a room humidifier control system that has alerts for the overall room humidity. Overall, this is a nice, easy to ready, humidity and Temperature display + options with audible alarms for Max and Minimum thresholds. I have one sitting on each of my enclosures with the probe inserted to measure humidity. Works Great. Would like to have seen included a probe attachment; such as a suction cup for glass and or a hook for wire enclosures.

We have two and have used them for years to measure both dryness and moisture. The readings differ by just a little bit. I think I returned a third one for being much further off calibration, so it may take a couple rounds when you purchase these. The device allows detach the sensor from the base and thus some ability to measure into places slightly distant from the base. Mostly, though, they reside on furniture and measure ambient air humidity. It does a good job of supplementing my dehumidifier readings as well, as those dehumidifier readings can be way off.

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!

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.

I have the latest version of this meter, with the words "Humidity Alert II" across the top. As far as I can tell, the only difference is the provision for temperature readings of 100 or more...notice the additional empty space to the left of the displayed temperature on the "II", compared to the original. Both share the same model number, however. Right out of the box this unit was correct on dew point. I checked it when all NOAA weather stations in the immediate area were reporting the same dew point (I had the unit outside). For this reason, I've had no need to adjust the calibration controls. The quick response and sensitivity of this unit are remarkable. With it standing on a table (it has a plastic support that folds out from the back for that), when I put my hand near it to operate the RESET or MAX/MIN buttons, the indicated dew point will begin to rise in a few seconds, responding to the moisture from my skin. For this reason, it would be a good idea to put the probe well away from the body of the unit - so that you can handle the unit without disturbing readings. The display is easily read from any angle. The only reason I withhold one star from my rating is the RESET and MAX/MIN buttons are quite stiff so you need to hold the unit securely in both hands to depress them. If the unit were securely mounted on a wall, this wouldn't be a problem. Front mounted, softer touch switches would be an improvement.

Works great in my music studio. Guitars require between 40-60% humidity. This is perfect measuring device for me.

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

- 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!

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.

Genuine product and good price.

Besitze seit Jahren ein Extech 445815, Nachdem ich in der Amazon-Suchmaschine nach Feuchtmessgeräten suchte, fand ich ein optisch ähnliches Gerät mit mobiler Sonde. Hiervon bestellte ich zwei Geräte und ward von der Genauigkeit schwer enttäuscht; wer das Lüften des Kellers und des Hauses ernst nimmt, kann mit TP-Differenzen von 3 Grad nicht zufrieden sein. Dann suchte ich gezielt nach dem Extech 445815, von welchem ich dann drei Geräte bestellte. Die drei Geräte haben eine gute vergleichende Genauigkeit und entsprechen auch dem langjährig benutzten Gerät. Ein Gerät musste in der Temperatur etwas nachjustiert werden - und dann stimmte auch dieses sehr gut. Und nun zu den Vorteilen dieses Gerätes: Das Gerät hat eine relativ sehr gute Grundgenauigkeit - die Grundmesswerte relative Feuchte und Temperatur lassen sich über zwei Potentiometer in Grenzen nachjustieren. Die externe Sonde sorgt für eine relativ schnelle Messwerterfassung (im Gegensatz zu Geräten mit integrierten Fühlern im Inneren des Gehäuses) - und dies ist sehr wichtig zur schnellen Entscheidung über das Lüften insb. des Kellers besonders in den Sommermonaten. Warum gleich mehrere Geräte - diese habe ich im Hause verteilt und eines dient der schnellen Feuchtigkeitserfassung der Außenluft (das Gerät sollte aber nicht dem Regen ausgesetzt sein - leidvolle Erfahrung vor einigen Jahren). Bei mir gibt es keinen muffelnden Keller - dazu muss aber auch die Einsicht der Frau beitragen, dass man bei schwülwarmen Wetter den Keller besser nicht wischt - ein oft mühsamer Überzeugungsprozess.