Have you thought of taking the heater back to BigAl for a refund or exchange? A properly designed circuit should not have given you the buzzing sound. The buzzing sound could be caused by a damped resonance. As long as it is solidly built, I don't think it will cause the heater to fail. I won't worry about it for now. When you have some saving, just replace it with a better one.
Good luck.
Nikki
Good luck.
Nikki
