The answer to 'water heater not cooling' is that the most common causes are a thermostat issue, sediment buildup, or a problem with the heating element. Symptoms include the water not getting hot enough or taking a long time to heat up. Solutions can range from adjusting the thermostat to flushing the tank or replacing the heating element.
If the water heater is not cooling properly, it's important to diagnose the issue quickly. Letting the problem persist can lead to further damage and more expensive repairs down the line. Homeowners may be able to troubleshoot and fix minor issues, but for more complex problems, it's best to call in a professional HVAC technician.