The whining, hissing, gurgling noise is normal when the electric element
is heating water.
Ours is located under the bed so we sometimes shut it off at night
just so we don't hear it when we're trying to sleep.
MORE annoying is having the water pump decide to cycle at 3 am
When my wife complains about something like that I just give her my standard
answer-- "it's all part of the adventure"