radon fan noise 4

https://radonmanometerreadingview.talesignal.com/posts/how-to-read-a-radon-manometer-reading-for-your-mitigation-system

That low hum from the radon fan is always there in the basement, a steady drone that fades into the background until you listen for it. It's not loud, just a constant reminder the system is working, pulling air through the pipes. Sometimes I wonder if it's getting a bit noisier, but my wife says she can't hear it at all.