Review on General Tools EP8710 Calibratable Multi Function by Chris Morales

I bought the General EP8703 because I wanted an inexpensive calibratable psychrometer. When I saw a used but like new one from a Revain third party for under $13 I couldn't resist. Unfortunately, it wasn't until after I placed my order that I noticed that the EP8703 didn't show the wet-bulb temperature I needed. Turns out you have to buy the more expensive EP8709 to measure wet-bulb temperatures. I think it's a bit disingenuous to call an instrument that can't measure wet-bulb temperature a "psychrometer", but luckily the EP8703 can easily be upgraded to be able to measure wet-bulb temperature (more on that below) . I was told that it was indeed in mint condition, but was calibrated so tight it only read 0.0% RH. Since the device can be calibrated, I had no problem calibrating it to read within its accuracy specifications. I disassembled the unit to check it out before deciding it was just a bad calibration issue. I was glad that the EP8703 and EP8709 use the same board. As far as I can tell, the only difference between the devices is that the HOLD, WBT, and MAX/MIN buttons on the EP8703 have been replaced with blank plastic covers. Otherwise the housing, sensors, circuit board, LCD and firmware are identical. All I had to do to essentially upgrade my EP8703 to EP8709 was add the missing buttons. Some tactile switches I had on hand worked great for this purpose. General is to be commended for being easy to update without breaking the EP8703 firmware. The photo I've attached shows the improved device and how well its wet-bulb temperature reading matches a direct reading taken with an accurate forward-facing wet-bulb thermometer. Admirer. This is the most accurate digital psychrometer I own. Build quality is decent for a budget instrument, but I don't expect it to last anywhere near as long as a unit that's many times more expensive for extended use in the field. The rubber mold feels good in the hand and the torsional rigidity of the case is much better than I expected. The device doesn't look particularly robust, but it should be sufficient for small field use or occasional DIY work. Overall I like this device for the price I paid.