The answer to 'water heater blowing hot air' is that the most common cause is a faulty thermostat or a problem with the heating element. This can happen when the thermostat malfunctions and fails to properly regulate the temperature, causing the water heater to overheat and blow hot air instead of heating the water to the desired temperature.
Other possible causes include a sediment buildup in the tank, a faulty dip tube, or a problem with the pressure relief valve. If the water heater is blowing hot air, it's important to address the issue promptly to prevent further damage and ensure safe operation.