Gas Water Heater Not Hot Enough. Another cause of hot water not being hot enough is sediment buildup in the water heater tank. A broken dip tube a buildup of sediment in your tank or a malfunctioning heating system.
If the flame is irregular or yellow in color it will not be as hot and won t heat up the water in the tank as effectively. The temperature of the hot water inside the cup should be hotter than the set temperature at least 10 f. Another cause of hot water not being hot enough is sediment buildup in the water heater tank.
Go to the article gas water heater thermocouple issues for information on this common repair.
A gas water heater cannot heat effectively if the burner is dirty or not functioning properly. While the water sits in and is heated by your water heater this debris settles to the bottom of the tank. First discharge one cup of hot water by using the tpr valve filling the cup at the free end of the discharge pipe. If your tank is too small for the number of people showering for example you may use up all the hot water before everyone is finished.