The answer to 'why is my water heater no hot water' is that there are several common causes, including a faulty thermostat, sediment buildup, or a problem with the heating element. The most common symptoms are lukewarm or cold water coming from the taps and the water heater not heating up properly.
If you're experiencing no hot water, the first step is to check the thermostat on the water heater to ensure it's set to the correct temperature. If the thermostat is functioning properly, the issue may be sediment buildup in the tank, which can prevent the heating element from working effectively. This is a common problem, especially in areas with hard water. You may be able to flush the tank yourself, but if the sediment is severe, it's best to call a professional plumber to handle it.