Review on 🌡️ Supco DSP1000 Digital Psychrometer: Accurate Dew Point & Wet Bulb Measurement, -22 to 212°F Temperature Range by Noah Lewis

This psychrometer is very accurate as advertised. I've compared the DSP1000 to two other HVAC diagnostic tools I own and they are calibrated and accurate to within 1.5 degrees. The downside is the 9 volt battery, which only has a few milliamp hours (mAh) and is more expensive to replace than an AA battery. However, because it has a large, easy-to-read display and backlight, it requires a higher voltage, making the device compact. Please note that this device consumes electricity even when it is switched off. The microprocessor needs standby power to know when the soft power button is pressed. There is a parasitic (static) drain that affects small capacity 9 volt batteries. I checked the current draw with my Fluke 287 and found that the unit draws 48 microamps (uA) when off. Doesn't sound like much, but the new battery was completely drained during winter storage. You must remove the battery if it is not used for a long time. The large display at the top always shows relative humidity (RH), while the lower display toggles between wet bulb, dry bulb and dew point in Fahrenheit or Celsius. Made in China for Supco.