An enlarged prostate is also known as benign prostatic hyperplasia (BPH), which is generally not associated with any prostate pain. However, an enlarged prostate can cause problems with urination.
When a homeowner turns on a faucet, the cooled water sitting in the pipes circulates to the faucet first, so the homeowner has to wait for hot water. A hot water circulation pump sends cool water in the pipes back to the water heater through a return line. A pump circulates this water through the water heater as needed to keep it hot. This continuous loop of water through the water heater ensures that hot water is always available.
Your water heater is filled from the cold water running in a tube to the bottom of the water heater. Since heated water rises, the top element just maintains the upper part of the water as the outlet hot side is on the top. So, If you start out with good hot water - and it starts to quickly turn cooler - you know the bottom element is bad + you can put your ear up to water heater and hear which element is on. I am with the person who said to change them both. Turn off incoming water supply - let off water pressure at another faucet.