It was a nasty small device sitting on the concrete floor that sounded like a jet ski was running constantly in my basement.
I was horrified to encounter this. It was pretty much unliveable. However, it also turned out it wasn't set up right.
The hose had been jammed under the floatie part that should turn it off when it's done and it was running full bore instead. That said, it was still atrocious when it ran, and I had to find another way to work this out.