HT607 Temperature Humidity Meter High Precision Digital Hygrometer with Ambient, Relative Humidity, Dew Point, Wet Bulb Thermometer, Min/Max Hold, LCD Backlight with Cover Protector

It's largely a matter of faith as to whether any hygrometer is giving accurate readings. There are ways of calibrating them, but these aren't all that reliable for a variety of reasons, like the fact that calibrating at one humidity level doesn't guarantee accuracy at other humidity levels. That's due to the fact that errors are nonlinear (not always off by a constant amount). Errors can be small (or even zero) over some portion of the range and large at others. Most home calibration methods, like the salt method, calibrate at the high extreme of the range, when our concern may be for accuracy elsewhere in the range.That issue is a tough one to get around, but digital sensors seem to have gotten better. In any case, taking any value of relative humidity as the gospel truth is a questionable proposition.What I look for is patterns of change in displayed RH as the environment changes and, to some degree, concurrence among multiple indicators. That's where this unit seems to excel. It gives me a reading that tracks (notice I didn't say "agrees") with other devices I have and with changes in the environment, such as running the heat like crazy and/or running a humidifier. Also, repeat measurements are reasonably stable under unchanging conditions. So, the readings are reliable (notice I didn't say "accurate").The various bits of information the unit provides are convenient. For example, the dew point is sometimes more informative than the RH. This unit displays that.To sum up, even though I have no certainty that the readings this hygrometer gives me are precisely accurate RH values, I think it does about as well as you can expect in a consumer-grade product. It's consistent, easy to use, easy to read, compact, and affordable. If you need more than that, then you probably should be looking at laboratory equipment rather than something like this hygrometer. I like it and recommend it for most uses outside of a laboratory. It might even be fine in a lab but I'd need further validation tests to know that. In the real world, at affordable prices, in a convenient form factor, I think this is pretty much as good as it gets.

This is a well made instrument, quality construction. I have compared its F Temp readings to a NIST bulb thermo I have and it within 1 degree, so accuracy is very good. However there are two issues. One is that it has a lot of measuring delay due to thermal lag of the heating and cooling of the sensor, so you need to let it stabilize in the environment you want to measure for at lest 3 minutes.The other issue is that it will not show the MAX / MIN at the same time as it displays the current temp. This is a severe issue, and for me it is really a deal killer. If you enable its MAX/MIN function its behavior is that it resets the previous MAX/MIN. After setting its state to record MAX/MIN, there is no way to have it read and report to you the current Temp. After the MAX/MIN state of the device is enabled all you can read out is those two measurements of what it has been recording as the MAX/MIN, This is a severe issue, as if you want to ask it for the current F you must disable its MAX/MIN state and return to its current reading state, which them resets the MAX/MIN it has been recoding. SO the previous MAX/MIN data is then lost. The device should be able to record MAX/MIN as it also reports the current Temp readings. I have a device by another manufacturer (ThermoPro TP357) that does this and also recodred a history log of the MAX/MIN. It is a far more useful device with much better programming logic.I do still use the PROTmex as its very large easy to read screen and it accuracy make it well suited to making current reading in a fixed location over period of time. It is a good, well made device, and I can recommend it, but please realize its failure to report and record MAX/MIN at the same time.as it shows the current temperature is a severe issue, You get one state or the other, but not both !

Quality construction, price and first Impressions are Good... Basic Functions are Temp, Humidity & Dew Point. Time will tell with length of service. Easy to navigate Celsius or Fahrenheit conversion, would recommend.

I don't have any high precision standards at home, because a good thermocouple device (type T) costs $100-200+ and a precision hygrometer is many times that. However, this gadget reads in a reasonable amount of time (I'd let it set 10 minutes before reading it, although a little less might be required) and it seems to be degree-ish accurate and 1-3% in humidity/dew point. It's actually hard to measure dew point with more than 2-3% accuracy so I wouldn't let that bum you out. Ground level dew points are strongly affected by microclimates anyway (did your sprinkler just run?) and indoors there are other challenges (is someone making chicken stock today?).Anyway, for a $20-30 gadget this works well, is exceptionally easy to use and has no obnoxious failings, and should satisfy the needs of people who just want an easy way to get a reasonably accurate reading of temp/RH/dew point at a random location in a few minutes.Stamp of approval from me.

Advanced Tech Review:This is a pro grade product which measures the Humidity Levels not as Relative Humidity RH but as Humidity Ratio HR or GPP Grains Per Pound of Pressure. In water damage restoration this device tells us how much GPP or grains of moisture there is per pound of Air Mass (14 cubic feet of air) and the temperature as well. This data then tells us what equipment (air movers, Air Filtration Devices AFD, ventilators, Dehumidifiers (dehu), etc...to use and where to locate them to establish our dry bulb levels (driest point we need to reach). It also tells us Dew Point which tells us if we will have condensation issues. For the price you can not go wrong, the accuracy is excellent. I would buy 2 or 3 to have on hand if they are lost or stolen, no big deal :)