My water heater quite woking. It is a double element unit. The top element is receiving 240V however the bottom unit is only receiving 120V. I understand that the top element feeds the bottom element. If the top element is bad would that cause the problem. I am getting no warm water at all.

Since you can obviously measure voltage, then you should be able to measure the resistance of the elements. Turn the water heater off first at the breaker.

Only one elemnt runs at a time.