Extech 445815 Hygro-Thermometer Humidity Alert with Dew Point Programmable Alarm warns of High Humidity Conditions

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.

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.

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've had this for only a few days now. I opened it shortly after it was received and placed it alongside an analog humidor hygrometer and a Netatmo networked indoor base ststion. Within a very short time the Extech was reporting the same humidity as the Netatmo. The analog humidor meter was reporting about 2% less humidity. The temperature on all 3 devices was within 0.4 degrees. Easy to read large display on this device.I like the detachable sensor on this Extech model. I bought this to use in my RV. I can place the sensor inside various compartments and other spaces and position the display where I can read and monitor it.Monitoring humidity within an RV is essential for comfort, health, and proper maintenance of an RV. This portable device will allow me to monitor the environment inside the RV, the compartment space underneath, or outside. It calculates and displays the dew point too, which is necessary to know if you want to avoid condensation on your windows and such, especially in the evening as it cools outside.I consider this an essential piece of gear for my RV and would not leave home without it. This one stays in the RV.

Works well. Does not have an external probe.