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Electric water heaters rely on thermostats to regulate the temperature of the water. If you’re experiencing issues with your water heater, troubleshooting the electric thermostats can help identify and resolve the problem. Start by checking the power supply and ensuring it’s properly connected. Next, use a multimeter to test the thermostats for continuity and replace any faulty ones. If the thermostats are functioning correctly, check the heating elements for any defects and replace them if necessary. Additionally, ensure the tank is adequately insulated and the temperature setting is appropriate. Regular maintenance and periodic checks can prevent future problems with the water heater electric thermostats.
If you possess an electric water heater, it uses one or two resistive elements to heat the water. Each of these elements is controlled by a thermostat specifically designed for hot water heaters. This thermostat turns on the element when the water temperature falls below a certain point and turns it off when the water temperature exceeds a certain point. If you’re experiencing a lack of hot water for showers or the water doesn’t get hot enough to be comfortable, it’s possible that the water heater is not functioning properly and one of the thermostats may be faulty.
There are two ways to check the thermostats using a multimeter. You can turn off the power and measure resistance to check for continuity, or you can leave the power on and check the voltage. However, it’s important to note that there is a real risk of electric shock, so make sure to wear rubber gloves, rubber-soled shoes, and use insulated tools for safety.
Preparing for a Test of the Water Heater Thermostats
If you’re experiencing a lack of hot water, it’s important to first determine if there is another reason for this issue. For example, if you have cold water in the shower but hot water elsewhere, the shower valve may need cleaning. On the other hand, if you’re experiencing a loss of hot water throughout the entire house, it is likely due to a malfunctioning water heater.
One possibility is that the breaker in the main panel has tripped, so it’s important to check this first. If it has tripped, you may be able to restore power simply by resetting it. If it hasn’t tripped, make sure to turn it off before removing the panels from the water heater to expose the elements and thermostats. You can leave the power off to conduct a continuity test, but you’ll need to turn it back on to perform a voltage test. Either test can provide conclusive results, so there’s usually no need to conduct both tests. However, it’s worth noting that the water in the tank needs to be above 90 degrees Fahrenheit in order to conduct a continuity test.
Performing a Continuity Test on the Thermostats
A continuity test will help determine if the thermostat circuit is open, indicating that a new thermostat is needed. To perform this test, keep the breaker off and set the multimeter to measure resistance on the Ω1 scale. Turn the top thermostat to its highest setting and touch one lead of the multimeter to the top terminal screw (marked #1) and the other lead to the terminal screw underneath it (#2). The multimeter should read 0. If you get a positive reading, it means the thermostat is faulty and needs to be replaced. If the thermostat has a #4 terminal screw opposite the #1 and #2 screws, that is the output to the lower thermostat. Test it by touching one lead of the multimeter to that screw and the other lead to the #1 screw. Again, the resistance reading should be 0. If it isn’t, then the thermostat is faulty.
If the top thermostat passes the test, it’s necessary to check the lower one. Turn the top thermostat all the way off and the lower one all the way on to ensure that the circuit between the two thermostats is open. Test the terminal screws on the lower thermostat. All readings should be 0. If you get a positive resistance reading, that thermostat is faulty.
Checking the Voltage
If the water in the tank is cold, you may need to perform a voltage check. Turn the breaker back on and be aware that all the terminals are now live, so proceed with caution. Adjust the upper thermostat to the highest setting and the lower one to the lowest setting. Set the multimeter to measure voltage in the 500-volt range and touch the leads to terminal screws #1 and #2. The meter should display a reading between 220 and 240 volts.
To check the lower thermostat, turn the top one to the lowest setting and the lower one to the highest setting. Place one meter lead on the top screw and the other lead on the metal body of the water heater. The reading should be between 110 and 120 volts. If it is not, the upper thermostat is not sending power to the lower one. Replace the upper thermostat. Repeat the test with the other screw. If either test shows a voltage reading of 0, the lower thermostat is faulty and needs to be replaced.
If both thermostats pass the test, the reason why you are not getting hot water is most likely related to the elements. Therefore, continue troubleshooting the problem by testing the water heater elements.
