I forgot to mention that this is the 2nd unit I bought (returned another one
that was same model for other reason) and the first one did not seem to
whistle at start-up. Is this still normal even if another unit didn't seem
to whistle?....just curious why this unit would whistle on start-up while
the other. It Also, I'm curious why the whistling does not happen if the
unit was powered down after a while. Just want to make sure this doesn't
indicate a potential problem.

Thanks,

J.