It can be very frustrating to find out you have no hot water in your home. Hot water is an extremely important part of our daily lives but we often take for granted that it will always be there. When a water heater stops producing hot water the likely culprit is either a failed heating element or thermostat.
So, how do you test a failed heating element? You’ll need to shut off the power to the water heater and remove the covers to the heating elements. Using a multimeter, you’ll need to check the element for continuity. Continuity means that there is no break in the electric current between two connection points. If continuity is broken, the heating element is bad and needs to be replaced.
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But before we get into that let’s explain how the heating elements operate, some other potential problems as to why you have no hot water, and how water heaters work.
How Dual Heating Elements Work
There are typically two heating elements in an electric water heater: the lower heating element and the upper heating element. Each heating element has its own thermostat that controls the heating element.
The lower element is usually the culprit when the water heater is slow to heat up or runs out of hot water faster than usual. However, if the water heater is not producing any hot water, the upper element is likely the problem.
In a dual heating element water heater, if the upper heating element fails, the lower heating element will not work regardless of whether the heating element is good or bad. This is because the thermostat attached to the upper element also controls power to the lower thermostat and lower heating element.
As either element can be the issue, you usually have to test both elements to be sure.
The rest of this article will discuss how to test water heater elements using a multimeter and continuity tester. We’ll also explain step-by-step how to how to replace the faulty ones.
Troubleshooting the Water Heater
Before assuming one of the heating elements is the reason you have no hot water, you should check some of the other common causes of water heater malfunction.
First, check to see if the breaker in the electrical panel box has tripped. There are a few reasons why a water heater breaker will trip. If your water heater breaker has tripped, try to reset it by turning it to the OFF position and then to the ON position.
Possible reasons your water heater will trip a circuit breaker:
- A failed heating element
- A failed thermostat
- An electrical short in the wiring circuit
If the heater keeps tripping the circuit breaker, you need to test both elements. Loose or faulty electrical connections can also cause a breaker to trip – in this instance, look for burned or melted wires at the circuit breaker or at the electrical connections at the top of the water heater.
Another option is resetting the water heater. Here’s how to go about it:
- Turn OFF the water heater power at the circuit breaker.
- Remove the top cover to the upper element. This is located along the top side of the water heater tank.
- Press the red reset button located above the upper thermostat.
- Put the cover panel back on and turn the circuit breaker back ON.
If the reset button trips and won’t reset, then the thermostat in either the upper or lower element is faulty.
How an Electric Water Heater Works
Electric water heaters are surprisingly simple machines.
A standard electric heater control circuit features two heating elements, an upper thermostat, a lower thermostat, wires, and a high-limit switch with a reset button. The two elements are controlled by the thermostats, which each is connected to.
The temperature of the thermostats can be set manually, depending on the water heater brand. They range from 90 degrees Fahrenheit to 160 degrees Fahrenheit. And of course, the higher the thermostat setting, the more electricity it consumes.
You should also make sure that both heating elements are never on at the same time. Running both elements at the same time will void any warranty on the water heater.
Additionally, when a water heater is new or repaired, the tank should be re-filled before applying power to the elements. If the elements are not completely immersed in water, they can burn out.
So, when the power is initially turned on, the upper thermostat sends electrical energy to the upper element until the upper third of the tank reaches the thermostat temperature setting.
When the top of the tank is heated, the upper thermostat turns off the upper element and transfers power to the lower thermostat, which turns on the lower element. The remaining water is heated to the lower thermostat setting.
The lower element maintains the tank’s temperature by turning on and off in intervals all day and night. And if the water temperature exceeds the setpoint, the high-limit switch trips and shuts off power to the elements.
When hot water is drawn, cold water quickly fills the bottom of the tank through the dip tube. Since the temperature is below the setpoint, the lower element starts to heat the water. When it reaches the upper third, the lower element shuts off, and the upper element kicks on. This heat cycle repeats.
In modern water heaters, when the water heater reaches the set temperature the water heater will enter into standby mode to conserve energy. On average, modern water heaters only run about 2 hours per day.
Keep in mind water heaters consume more electricity during the winter months as the elements must heat longer to reach the setpoint temperature.
How to Test Water Heater Elements
To determine if the heating elements have failed, you can either use a non-contact voltage tester or a multimeter. With a multimeter, it’s essential that you know how to interpret the readings.
Tools You’ll Need:
Step 1: Turn the circuit breaker power off
The circuit breaker is located inside the main electric panel. Electric water heaters typically have a 30-amp double breaker. Look for the breaker labeled Water Heater. If your breakers are not labeled, you may need to contact an electrician to properly label the circuit breakers.
Step 2: Open the upper and lower side panels on the water heater
A standard 40-gallon water heater or larger will can have two panels located on the side of the water heater tank. Smaller water heaters may only have one panel. Remove the screws holding the panels in place and set them aside in a safe place.
Step 3: Remove the insulation covering the elements and thermostats
The insulation material differs from one water heater to the next, depending on the age of the unit. Fiberglass is synonymous with old water heaters; newer ones have tight-fitting foam while the latest ones have thicker foams. Dealing with foam can be a bit tricky, so cutting it back will likely be necessary.
Step 4: Remove the plastic safety covers
After the insulation has been removed you’ll see a plastic cover over the thermostat and heating element. This plastic panel is clipped in place. Simply remove the plastic panel to expose the thermostats and heating elements.
Step 5: Use a non-contact voltage tester to check if the electrical connections have power
This step is necessary for safety purposes just to confirm there is no power to the heating elements (in the event you turned off the wrong breaker). Place the tip of your tester on each black, red, and white wire. If the tester repeatedly flashes like an alarm, it means the voltage is present. If the tester doesn’t light up, no voltage is present, so you can go ahead and test the elements.
Step 6: Disconnect element wires
Check to see if the wires are burned or melted. Just use your eyes and nose only. When you discover a burned/melted wire, replace the part.
Step 7: Check the continuity of the elements
There are two tools you can use to check the continuity: a continuity tester or multimeter.
You can use a Continuity tester in three primary ways:
- Fasten the alligator clip to one of the element screws and touch the probe to the other screw. If the tester doesn’t light up or buzz or react slightly, the element is faulty.
- Using the same procedure, touch each screw to the bare metal part of the water heater.
- Using the same procedure, touch each screw to the metal base of the element.
If the elements don’t pass all three tests, they are flawed and need to be replaced.
A multimeter is not as straightforward as the continuity tester. It features two wire leads fitted with metal probes, one red and the other black. The first step is to set the multimeter dial to Rx1k (resistance times 1000 ohms). Repeat all the three tests as instructed above.
When testing both element screws, as indicated in test 1, the tool should register around 16 ohms for a 3500-watt element, 12-13 ohms for 4500-watt element, and 10-11 ohms for a 5500-watt element.
If the element fails to correlate with the readings above or show any readings, it is faulty.
If you repeat tests 2 and 3 and the multimeter needle moves, the element is bad and needs to be replaced.
If the elements pass all three tests, the thermostat might be the problem.
How to Replace Water Heater Elements
Replacing a heating element is even easier than testing one. Make sure the replacement has the same volts. As for wattage, it can either be the same or lower. Lower watt element tends to last longer but produces less heat.
Tools You’ll Need:
- A garden hose
- Heating element wrench
Before replacing the heating elements, you’ll need to drain the water heater. For a step by step guide to drain your water heater, see our article Water Heater Maintenance Tips – Gas and Electric Tank Water Heaters. Once you’ve drained the water heater proceed to Step 1 below.
Some videos on YouTube show heating element replacement without draining the water heater. I do not recommend this method because if you have trouble getting the element in place or need to clean the inlet, the bucket may not hold all the water from the water heater.
Also, draining and flushing the water heater is something that should be done annually to flush sediment from the water heater. If the heating element is bad it’s likely caused by corrosion which means the anode rod is also bad and needs to be replaced.
Take this opportunity to provide a thorough service of your water heater.
Step 1: Unscrew the faulty element
Using the heating element wrench, turn the element in a counter-clockwise direction to loosen it. Pull the element straight out from the tank. Be sure the old seal is completely removed.
Step 2: Install the new element
Check the type of heating element your water heater has. There are two types of heating elements; screw-in heating elements and flang heating elements. If you are unsure which you have, take the old heating element with you to the home store for comparison.
Slide the replacement heating element into the opening. Be sure the new seal that came with the new heating element is in place and tighten it with the heating element wrench.
Step 3: Reconnect the wires to the heating element
Reconnect all the wires and secure them tightly with the screwdriver. It doesn’t matter which wire goes to which terminal.
Inspector Tip: It is recommended that both heating elements be replaced at the same time even if one is still in working order. Chances are that the other element is in the same condition and could fail at any time.
Step 4: Refill the water heater
Remove the garden hose, close the drain valve, and open the cold water supply valve to refill the water heater tank. Once the water comes through the faucet close the faucet. Check for leaks around the heating elements and tighten if needed.
Step 5: Secure the panel covers
Put the plastic cover and insulation back into place. If the thermostat is exposed to cool air, it might interfere with the temperature readings. Put the side cover panels back in place and secure with the mounting screws.
Step 6: Turn the power back on
Turn the circuit breaker back ON at the electrical panel box. Do not turn the power ON prior to filling the tank with water. This can damage the new heating elements. Recovery will take approximately 1 hour.
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