In the 1910's Goddard became world-famous for his ideas about "feeble-mindedness" particularly his belief that it was a hereditary trait. His seminal work, The Kallikak Family, studying two strains of the same family (one strain considered normal, the other considered "defective") became an international bestseller and became extremely popular in Germany under the Nazi regime. He personally instituted a testing system at Ellis Island in order to keep these "feeble-minded" people out of the United State used to reject an estimated 80% of potential immigrants and forcing them to be deported back to their home country.
It was in the midst of Goddard's work on intelligence testing that he coined the word "moron." He created a classification system for those on the bottom end of the intelligence scale: people whose IQ was between 0-25 would be classified as idiots, people with an IQ between 25 and 50 would be imbeciles and those with an IQ between 50 and 75 would be classified as Goddard's own invention: morons. He derived the word from the ancient Greek moros meaning dull or foolish.
Could be some scale build up on heating element or you may have a leaky bypass or check valve on your heater. Which maybe more noticeable on the electric heating operation only side of the heater. I've always used gas to heat the water and electric to keep it heated along with turning both gas and electric on initially to speed up heating or back to back showers.
Starter solenoid should be an intermittent duty solenoid activated by the key switch. The house or chassis isolation solenoid will be continuous duty solenoid. I would have the starter tested to see if the amp draw is too high.