Bests & Worsts Reviews from Amazon

I purchased this detector in January 2017, so I could monitor the radon in the lower level of my house. I live in an area with high radon levels. Set-up was super easy - just pull the plastic tab sticking out of the battery compartment to turn it on. It immediately goes to calibration mode, then it goes into detection mode. You will not get any readings until after the first 24 hours. This is not an "instant read" device, like a digital thermometer. It is meant to remain in an area of your house, where it will continuously monitor. The lower digital display toggles between the 1-day and 7-day averages, while the upper display gives the radon average since first activating. I placed my detector on a shelf in the amusement room. The first few weeks, I checked the readings every day. They seemed consistant from day-to-day. Then I only checked it a few times a month. I did notice that radon levels would increase after a heavy rain; perhaps the water in the soil would "push" the radon to an area of less resistance? In August 2018, I checked the detector for the first time in many months. (With my readings being fairly consistent, I had stopped checking it all the time.) I was surprised to see the lower display reading "0.00", because I knew it was impossible to have zero radon in my house. I moved the detector to the kitchen, where I could keep an eye on it. After a week of 0.00 readings, I finally pushed the reset button on the back. It went into calibration, then displayed "Err 4". I tried new batteries, recalibrating again, etc. but still stuck with "Err 4". I emailed Airthings customer service, explained my situation and asked if there was any way to get my detector working again. They replied with several tests for me to perform, and asked me to report back. Everything I did didn't change it from the "Err 4" display. To my surprise, they said they would be sending me a brand-new unit! Being seven months past the warranty end, I certainly wasn't expecting this! All I had to do was email photos of the front and back of my detector, along with my original Amazon receipt. I was asked to dispose or recycle my old detector. What fantastic customer service! A company that stands behind it's products and makes customer satisfaction a priority! Thank you Airthings!