I got the Wen air exchanger/filter for my birthday in November and got it installed late December. It has been working great except for one thing. At first I thought that maybe I didn't set the timer on the unit, it was still running long after I left the workroom. It was on again a few other times. Again thinking that I just didn't turn the timer on. Well, I haven't been in the workshop for over a week (fractured arm) and it was running yesterday. I will call Wen on Monday, but has anyone else experience this? If so, what did you do to fix?