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Storage tank water heaters have thermostats and temperature-sensitive valves that monitor and regulate the temperature of the water in the tank. These components ensure the tank produces evenly heated water when you turn on a faucet or shower knob. Therefore, if your water heater is producing lukewarm or cold water, you need to check it for defects. Below are the three most likely causes of inconsistent water temperature in your electric water heater.

Faulty Tempering Valve

Storage tank water heaters can harbor legionella bacteria if the water temperature is between 77 and 113 degrees Fahrenheit. Therefore, the hot water stored in the tank should maintain a temperature of at least 140 degrees Fahrenheit to prevent the growth of legionella bacteria. Unfortunately, this temperature is too high for domestic use and can cause scalding. This is why most storage tank hot water systems have a tempering valve.

A tempering valve is a valve installed on the water heater's outlet. As hot water leaves the tank, the tempering valve mixes it with cold water to lower its temperature. The valve helps keep the water in the tank hot enough to prevent bacterial growth while ensuring the system supplies water at a safe temperature. However, if the tempering valve develops mechanical faults, it can provide too much cold water, leading to temperature fluctuations in the hot water supply. Replace the valve to access evenly heated water in your faucets and fixtures.

Defective Thermostat 

Your electric storage tank water heater has a thermostat that senses the temperature of the water and signals the heating elements to turn on. Dual-element water heaters have two thermostats—one for each heating element. If one or both thermostats are defective, they may send false signals to the heating elements.

For example, a faulty thermostat can signal the heating element to turn off before heating the water to the pre-set temperature. As a result, the water supplied to the home will be lukewarm or cold. If your water heater has a faulty thermostat, replace the component to restore proper heating. Also, check the wiring connection between the thermostats and the respective heating elements.

Malfunctioning Heating Element

Electric water heaters use heating elements to heat water. Older units have a single heating element, while modern ones have two—one at the top of the tank and another at the bottom. If a heating element is defective, the system will take longer than usual to heat the full tank of water to the pre-set temperature. Thus, the water available after the tank's recovery period will be lukewarm. You must replace the faulty heating element to ensure fast and efficient heating.

It can be hard to pinpoint the exact problem in your hot water system without professional help. Contact a plumbing contractor for more information about water heater repairs.