Between these two pipes is a large water container. These elements use a lot of electric power so they don t operate simultaneously. Instead, the top element operates until the water near the top of the hot water heater reaches the desired temperature and then the bottom element operates until the water near the bottom is also at the desired temperature. The water heater then turns itself off and waits until more heating is required. Both heating elements project into the same hot water container inside the water heater.
Hot water floats on cold water, so there is no convection.
The cold water near the bottom of the container is essentially unaffected. How water should be extracted from the top of the container and cold water should be added to the bottom of the container. To replace this hot water, cold water should be added to the bottom of the tank, where it won't mix with any hot water that might still be present in the container. When a small amount of hot water is removed from the tank, cold water is added to the bottom of the tank. This water is then heated by the bottom heating element.