To avoid confusion over debits and credits, avoid thinking of them in the way that they are used in everyday language, which often refers to a credit as increasing an account and a debit as decreasing an account. For example, if our bank credits our checking account, money is added to it and the balance increases.
One way to reduce the frequency of this occurrence is to maintain an air pocket at the top of the water heater tank. This air pocket will form in the tank by design - however, it will be reduced over time by the everyday use of your water heater. To replenish this air pocket: Turn off the water heater.
Tank-style electric water heaters use two heating elements to warm the water, one at the bottom and one nearer the top. Power surges, mineral build-up and age can cause either element to fail or burn out. If your water heater produces only lukewarm water, suspect a bad top element. If it produces hot water in short supply, the probable cause is a bad bottom element. Test both to be certain. Follow these steps to check the heating elements in a hot water heater.