How To Test Hot Water Heater Thermostat

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What Causes A Faulty Water Heater Thermostat

Water Heater Not Heating? Thermostat Testing

Any number of issues can cause a faulty thermostat. Improper installation may put excess pressure on the unit itself, rendering it defective and unable to control the temperature of the water. Corrosion on the unit and rust and sediment buildup can also affect its ability to regulate your hot waters temperature correctly.

How Does A Thermostat Work

Normally, an electric water heater has three main features. They include a heating element, a thermostat and a switch to prevent the unit from excess heat.

You can use a thermostat to produce heated water to suit different purposes. For instance, the level of heat required for washing might be different from the one needed for showering. Furthermore, it controls the current that moves to another thermostat or heating element.

An electric heater with a storage tank of at least 30 gallons comes with two heating elements with a thermostat on each of them. The thermostat on top acts as the primary one while having a high limit switch. But the lower one detects any change in the temperature of the water.

Both thermostats do not have the same features. They even do not work at the same time.

The high limit switch is found on the location as the upper thermostat. It also has a button that stops it from working, especially when the water goes above 170F. To restore it to default settings, press this button.

To set the thermostat on a water heater, you will need to adjust both thermostats to similar temperatures. Alternatively, you can adjust the upper element to a lower temperature thereby allowing the one underneath to activate first.

For water heaters that have smaller tanks , a single thermostat and heating element handle temperature control. But they use a high limit switch like the larger water heaters.

S To Test A Water Heater Thermostat

  • Turn off the power. Check that the power is off before starting! Then double-check. Then triple-check. It is extremely important that its turned off, so you dont hurt yourself.
  • Go to the circuit board and locate the breaker for the water heater. It may be labelled as something else, depending on who installed the system, but it should be clear enough that youd know its for the heater. However, if you are unsure, stop right here and call a professional.
  • Access the thermostats. When you head to your water heater, you will notice two panels: one that is higher up on the unit and one that is lower down. These cover the thermostat and its components.
  • Remove the access covers. Use your flathead screwdriver to unscrew the top and bottom access covers. Inside, there will be insulation with a cutout flap for the thermostat.
  • Flip the cutout flap up. You can also flip it down, depending on how it was cut. Either way, make sure that its not blocking anything.
  • Optional: Tape the flap out of the way. If you managed to get some tape, stick that flap away.
  • Remove the plastic cover. It will rest on top of the thermostat so with the help of your screwdriver, take it off and place it somewhere safe.
  • Set up your multimeter. Set your multimeter dial to the lowest setting for ohms of resistance.
  • Place your multimeter lead on the reset terminal. This should be located right next to the reset button. It would have also been the terminal that did not have any power wires running to it.
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    What Causes A Hot Water Heater Thermostat To Fail

    A heater thermostat can malfunction for a variety of reasons. Most of the time, a broken thermostat or heating element is to blame, but it could also be a broken reset button or a loose electrical connection. Call in a plumber who has experience troubleshooting this type of problem or if you’re baffled about how your thermostat is acting.

    Theres Not Enough Hot Water

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    When you first flip the circuit breaker on before turning on your hot water faucet, the electric current runs through two wires and completes a circuit to the heating mechanism of the water heater. If the thermostat isnt sensing that it is not hot enough, electricity will not run through those wires, and no heat will be produced.

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    Take The Meter Reading On The Lower Thermostat

    After testing the upper thermostat and it is working fine, check the lower thermostat by repeating the same process.

    Have in mind that there are only two terminals in the lower thermostat. Do check the reading to see if it’s zero.

    If you’re convinced the thermostats are in optimal condition, you can test for your heating elements. But if one or more of the thermostats need to be changed, read on.

    How To Check A Hot Water Heater Thermostat

    Here is a complete guide on how to check your water heater thermostat.

    1. Ensure you turn off the water heater power off and remove the access panels, plastic safety covers, and any other insulation.2. Use a screwdriver to turn set the upper thermostat at its highest possible temperature and the lower thermostat to its lowest temperature setting.3. Turn the water heater power back on and use a multimeter to check that there is power coming to the water heater. The multimeter readings ought to be ranging between 220 and 240 Volts. If there is now reading on the multimeter, you have a faulty upper thermostat.4. Now check the lower thermostat. Set the upper thermostat at the lowest temperature setting and the lower one at the highest temperature setting.5. Check the lower thermostat for voltage and if there is power, allow the water to heat for a while and recalibrate the thermostat. If it clicks, it is good to go until the next check.6. If you fail to get voltage readings on the element, place one of the probes on the top screw of the element and the other on the water heater tank. You ought to get a reading of at least 120V. Check the lower screw if it has power with one probe on it and the other on the water tank the reading ought to be the same as that of the upper screw.

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    Exchange The Faulty Thermostat With The New One

    We are assuming that you already have the new thermostat and now you are fully prepared to install it.

    To deploy the new thermostat to the exact location, you will need to follow the same process. If you get confused about how to attach the wires, take help from the picture that you have clicked earlier.

    What’s Inside A Water Heater And How It Works

    How To Check Electric Water Heater Elements & Thermostats With Power On & Off

    Most residential electric water heaters have two heating elements: one near the top of the tank and one near the bottom. Power enters the top and runs to the high-temperature cutoff switch, and then to the thermostats and elements. The top and bottom elements are controlled by separate thermostats. When the water on the top of the tank is hot, the top element turns off and the lower one heats. The upper and lower heating elements never come on at the same time.

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    Set Up The New Thermostat

    Fix the new thermostat into its corresponding clips. Make sure it rests correctly on the surface of the storage tank. Attach both circuit wires to the corresponding screw terminal. Lock them by tightening the screws.

    Adjust the temperature on the thermostat to your preferred setting. Here, you will need a flat blade screwdriver. It is suggested that you set the temperature to 120°F.

    Why Is My Water Heater Always Shutting Down

    You’ve adjusted the temperature and double-checked your thermostats to ensure they’re all operating well. But why is the water heater still shutting down? As previously stated, the reset switch integrated into the thermostats is responsible for this.

    The reset switch turns off the heater when the water temperature inside the tank becomes too high. Here are a few hypotheses as to why this might be happening.

    • The heating element is on its last legs: Your heating element’s integrity may be jeopardised as its ages. As a result, it will not function properly. If this happens, the water in your tank might get too hot, which would cause the reset button to trip. The heater will then shut down as a result of this.
    • The ECO Switch: The ECO switch, which works in tandem with the reset function, prevents the water from becoming overly hot. It might deteriorate and break over time. Although this would not force the heater to shut off on its own, it is usually an indication of additional issues.
    • Poor wiring: If everything else is in working order, the reset switch could be tripping due to a short circuit produced by bad wiring. If this wiring gets wet, directly or indirectly, it’s a big problem that a professional should take care of. Do not try to repair or diagnose the problem on your own.

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    Test Your Water Heater Thermostat In Minutes: 13 Steps

    Because youve had a particularly long day, youve made the decision to take a shower before retiring to bed. When you turn on the faucet, youll be sprayed with ice-cold water. However, where is the hot water? This is nothing new. It will never come! Uh-oh! If this seems like a familiar scenario, you may be the victim of a malfunctioning water heater thermostat, but how can you be certain? We can determine whether or not the thermostat is the source of the problem with a few simple tools and some good old-fashioned elbow work, though.

    • A flathead screwdriver and a digital multimeter are the equipment youll need for this project.
    • Its also a good idea to get your hands on the heaters service manual if you have one.
    • It is possible that you will get wounded if the essential safeguards are not performed.
    • With that being said, lets get started.

    Test The Thermostats With The Multimeter

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    You are now ready to check hot water heater thermostat with your multimeter. This step can be challenging for first-timers, but we will go through each process one at a time.

    First, touch the reset terminal with a multimeter probe. Do not worry about which electrode to use because electrical resistance is not directional. You can find the reset terminal next to the thermostats reset button.

    Next, place the other multimeter electrode on the thermostats left side terminal, ensuring to maintain a distance from the first probe.

    Third, read the value in the multimeter. You will want the electric water heater thermostat test to return a zero or close-to-zero value, indicating your thermostat is still functional. However, if the multimeter reads 1.00, you might have a busted thermostat that requires replacement.

    Lastly, reposition the second lead to the thermostats right-side terminal, while keeping the first probe on the reset terminal. Read the results and interpret accordingly .

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    What Should Water Heater Thermostats Be Set At

    Electric water heater thermostats come preset from the manufacturer, usually at 110 degrees. You can raise the temperature to the maximum, usually 150 degrees Fahrenheit . We recommend a maximum water temperature of 120 degrees Fahrenheit because a higher setting can become a scalding hazard for young children or the elderly.

    High Limit Reset Button

    Determine whether the high limit reset button has tripped or not. Here are the instances that trigger the button to trip:

    • The thermostat is out of calibration
    • The heating element is failed
    • Thermostat contacts have closed fuse.

    Make sure you have tripped the high limit reset before tinkering with the thermostat of your electric water heater.

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    How To Change Out A Faulty Water Heater Thermostat

    It is very easy to change out a faulty thermostat.

  • First, you will turn the power off to the unit.
  • Then, you will remove the outside covering and insulation.
  • Take your digital multimeter to verify that the power is completely off.
  • Once you have determined the power source is dead, you may begin unscrewing the thermostat and disconnect the wiring.
  • When you have the thermostat off and out, you can replace it with a new one.
  • Remember to connect the wires the same way you removed them and reattach the new thermostat screws.
  • After the installation is completed, you may turn the power back on and check that it works properly.
  • Water Heater Thermostat Faqs

    Water Heater Not Heating? Thermostat Testing Step By Step

    Electric water heater thermostats are typically pre-set by the manufacturer to 110 or 120 degrees Fahrenheit, depending on the model. You have the option of increasing the temperature to the maximum setting, which is typically 150 degrees Fahrenheit, if necessary . The maximum water temperature setting should be no greater than 120 degrees Fahrenheit , since a higher setting might provide a scorching threat to small children and the elderly.

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    What Is A Water Heater Thermostat

    A water heater thermostat is an adjustable device that is attached to your water heater to control, change, and regulate the temperature of your hot water.

    They are usually mounted to the surface of your water heater and placed on a bracket that holds the device to your hot water tank.

    This makes it, so the backside of your thermostat is fully connected to your hot water tank and is designed to react and respond to the temperature of this surface.

    Water heater thermostats that are placed on the tank are usually located near or behind the access panels of the device.

    Reattach The Cover Panels

    Inserting the new thermostat into the retaining bracket that holds the old thermostat in place will allow you to precisely position it in the desired area. Wires should be reconnected to their original locations on the terminals. Make use of the prior photograph as a reference if necessary. Inspect the connections to ensure that they are solid. Check to see that the thermostat is securely attached to the water heater, or else the thermostat may not operate correctly. After that, adjust the thermostat to the temperature you like for your water.

    These modifications may be accomplished using the flathead screwdriver.

    The following is an insiders tip: If you intend to replace your heating element with your new thermostat, you will first need to empty the water heater.

    For information on emptying your water heater as well as other maintenance suggestions, please check our articleWater Heater Maintenance Tips for Gas and Electric Tank Water Heaters.

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    How To Replace A Water Heater Thermostat

    Replacing a water heater thermostat is very easy, and you should be able to do it yourself without any problem. However, many homeowners feel more comfortable hiring a professional plumber to handle the job.

    You’ll need a Phillips and flatbed screwdriver, a multimeter, as well as your new thermostat. Be sure you’ve purchased the correct thermostat for your water heater.

    Improving Your Heaters Performance

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    The biggest thief robbing a water heater of efficiency is sediment. Sediment is formed out of minerals like calcium and magnesium that are found in hard water. These undissolved minerals, along with any sand that might be suspended in the water, collect on the bottom of every tank-type water heater, reducing its capacity to store hot water.

    This crusty layer of elements affects gas-fired and electric heaters in different ways. In the electric units, the sediment builds up until it buries the bottom element. It displaces the cool water that normally surrounds the element causing it to overheat.

    A homeowner may not even notice that the element has failed, only that the water heater just doesnt seem to keep up anymore.

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    When To Replace Your Thermostat

    Most hot water heaters have two thermostats. Youll find them at the top and bottom of the tank. Refer to your manual . If you dont, you can probably download one from the manufacturers website. Simply search for your brand, model, and enter owners manual at the end.

    If your water heater isnt working properly, its likely the thermostat is the culprit. Luckily, repairing a water heater thermostat is an easy fix that can be solved by most homeowners. While its unlikely that both thermostats will fail at the same time, its a possibility and recommended that you replace both thermostats if one starts to fail.

    If your top thermostat begins to fail, the entire water heater will stop producing hot water. On the other hand, if there is a lower thermostat failure, then youll notice the water being only lukewarm or hot before quickly running out since only the upper portion of the tank is being heated.

    How To Test Water Heater Thermostat 10 Steps Guide

    In order to test a thermostat, you will need two things. First of all, you will require the tools to operate like a screwdriver and a digital multimeter, and the second thing, the most important one is the proper guidance. For a smooth process, here are the steps for how to test a water heater thermostat. Lets give it a quick read.

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    Deactivate The Power Supply

    Shut off the power supply by switching off the breaker that is connected to the water heater. Normally, water heater breakers consist of two separate single-pole switches with a 30 amp rating. But some models offer more amps.

    Take out the panel that protects the thermostat and heating element of your electric water heater. Since some models have screwed panels, you might need to work with a screwdriver. Ensure you remove the insulation at the back of the panel but avoid touching the wires.

    Make sure there is no current in the thermostat to avoid electrical shocks. At this stage, you can use a non-contact voltage tester to check the screw terminals and wires.

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