If you can take it back. Do so. They are lousy heaters.
I have to disagree on this and disagree very strongly, I own a total of 22 of these heaters, most of which have seen over 5 years of service, some as much as 12. I have yet to have one fail or cause me a problem, the only one I ever had crack was left turned on when I drained the water it was in, and it didn't explode, only cracked slightly. I have one of my oldest 150 watts that the indicator light burned out on but it still holds the tank temp perfectly year round, despite the fact that you can't see when it is on or off. Although if I ever do have a problem I will switch to one of the more expensive heaters, I simply don't have any reason to change brands. If all of the products I used preformed as reliably as my visi-therms, I'd be a very happy person. IMO and IME you made a good choice with the visitherm deluxe. I doubt you will be dissapointed.