Hot water is essential for hygiene, laundry and dish washing. A faulty thermostat can either cause water to be over heated, under heated or not heated at all. Thermostats in water heaters are designed to monitor the temperature and turn the heating elements on and off as necessary. Hot water should be kept at 120 to 125 degrees. Replace your water heater thermostat if it’s not maintaining consistent temperatures.
Make a note of the manufacturer of the water heater and check the nameplate with the Underwriters Laboratory seal for the model number. Clarify if this is the upper or lower thermostat in units that hold two. Bring the make and model number to the hardware store for assistance in finding parts, or visit the manufacturer's website and type in the model number to get specifications for the thermostats.