Water Heater Temperature Sensor Failure—What To Do?

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The temperature sensor function on a water heater is as a signal switch. It signals the gas control valve to either release or terminate the gas supply based on the water temperature compared to pre-determined temperature levels. However, like any other mechanical part, the temperature sensor may malfunction, leaving you wondering what you can do about it. We consulted the experts, and this is what we discovered.

When a water heater temperature sensor fails, the water can overheat, remain cold, or you might have insufficient hot water. To troubleshoot the temperature sensor:

  1. Use a multimeter to determine the resistance reading of the temperature sensor.
  2. Compare the sensor's resistance reading to the expected reading based on the manufacturer's chart for sensor resistance at different temperatures.
  3. Replace the sensor if the resistance readings are not within the recommended range as it is faulty.

You now know what you can do if the water heater temperature sensor fails. Tag along as we discuss how to troubleshoot your water heater. We will also tackle maintenance tips for your water heater. Let's get into it.

Hands young women set the temperature of the water in the electric boiler, Water Heater Temperature Sensor Failure—What To Do?

How to troubleshoot water heater problems

Shower and electric water heater in the bathroom

A well-functioning water heater ensures there is sufficient hot water in your home. However, the water heater can malfunction, necessitating intervention to restore functionality.

Some common issues with water heaters are:

  • Water temperature concerns; the water can be too hot, too cold, or you have inadequate hot water. These issues can result from no power, a faulty temperature sensor, a damaged heating element, or crossed hot and cold connections.
  • Water leaks due to a faulty T&P relief valve, overheating, or incorrect water pressure.
  • Discolored water could be due to a corroded anode rod.
  • Odd noises as the water heater runs could be due to sediment build-up.

We discuss how to troubleshoot a malfunctioning temperature sensor below. Further, we will address T&P valve issues, how to replace an anode rod, and eliminate sediment build-up under the maintenance of a water heater section. Read on!

Inspecting the water heater's temperature sensor

The temperature sensor sends a signal in the form of small electric currents to the gas control valve to release gas or stop sending gas to the burner when the water temperature in the tank falls below or rises above a pre-determined level, respectively.

If it fails, it will not send signals that trigger or terminate calls for heat as required. Consequently, your water will not be at the right temperature.

If the fault code error is due to a high tank temperature, switch off the gas control knob for a few minutes and light the pilot as usual. In case the error persists, test whether the temperature sensor is working.

  1. Disassemble the gas valve, leaving the temperature sensor attached to the water heater's backplate.
  2. Set the multimeter to ohms.
  3. Attach pin probes to the multimeter. The pin probes enable you to test the pins on the small plastic connectors without damaging them.
  4. Insert one pin probe into the center hole and the other into an outside hole, and note the resistance reading.
  5. Measure the water temperature.
  6. Use the manufacturer's chart to compare the expected resistance at different temperatures with your readings.
  7. If the temperature reading is ok, replace the gas valve. However, if the reading is off, replace the temperature sensor.

This digital multimeter accurately measures resistance. Check it out on Amazon.

Maintenance of a water heater

Plumber attaches Trying To Fix the Problem with the Residential Heating Equipment.

Taking care of your water heater improves its operating efficiency and extends its useful life. While there are practices that you need to do once, some maintenance exercises need to be performed annually. Regularly performing these activities will boost effectiveness and reduce your water heater's operating costs.

Insulate the water heater

Insulating an electric water heater can significantly reduce standby heat losses by 25% to 45% and reduce water heating costs by 7% to 16%.

It is essential to consider your local codes or the manufacturer's regulations before insulating the water heater as you might expose yourself to these risks:

  • You might unknowingly obscure the operating instructions and safety warnings.
  • You might cover the control panel or access areas such as shut-off devices and the temperature and pressure release valves.
  • You might also obstruct air passages needed for combustion or draft, leading to unsafe operation.

You should mark and cut out the insulation where the control panel, the pressure release valves, temperature control, operating instructions, and safety warnings are. Further, ensure that you turn off the water heater before insulating it for your safety. Turn it back on once you complete the exercise.

Insulate the pipes

Insulating the hot water pipes minimizes heat loss, enabling your pipes to deliver water that is 2°F–4°F hotter than that from uninsulated pipes. So, you can lower the water temperature setting since you won't need to accommodate heat loss. You will also conserve water since you won't have to wait for hot water for long when you turn on the tap or showerhead.

If you use a gas water heater, keeping the insulation at least six inches from the flue is advisable. However, if the water pipes are within eight inches of the vent, you should use fiberglass pipe wrap that is at least one inch thick and does not have a facing. Secure the pipe-wrap around the pipe using a wire or aluminum foil tape.

Check out fiberglass pipe insulation on Amazon.

Read this article to learn more about insulating water pipes: What Is The Best Insulation For Pipes?

Drain the water tank and wash out the sediment

Heating hard water causes sediments to ooze out of the water. As the deposits accumulate at the bottom of the water tank, your water heater's efficiency reduces since the temperature sensor will not be as sensitive to temperature changes as required.

Also, the sediments cover the heat transfer surface; so, the water heater uses more energy to heat water and cause noise as the water heater runs.

You must disconnect an electric water heater from the power source before draining it. If you use a gas water heater, turn the gas control to pilot.

It is advisable to drain the water in the tank first before filling it with cold water to avoid stirring the sediment rather than flushing the tank. Once you drain the tank, keep adding water until clean water flows through the drain hose. Close the tank drain, refill the tank, and then re-set the pilot control or plug in the water heater.

Inspect the T&P Valve

Although the T&P valve is never intentionally used, it is critical in an emergency or if the water heater malfunctions. Because it is responsible for excess temperature (T) and pressure (P) relief, it can avoid the potential explosion of your water heater.

  1. Ensure that the discharge tube is securely attached to the T&P valve. Further, ensure that the discharge tube points straight downwards and ends a few inches above the floor.
  2. Place a bucket or a water heater pan below the tube.
  3. Pull back the T&P valve's metal lever to start some water discharging into the bucket.
  4. Release the lever and observe whether it snaps back to its original position. If the lever does not snap back, the valve is faulty and should be replaced immediately.

Since the T&P valve is rarely used, the mineral build-up can cause it to stiffen over time. Opening or closing the lever several times can remedy the stickiness. If the problem remains unresolved, replace the valve.

If the T&P valve drips continually, shut down the water heater and let it cool down, then remove and rethread the valve into the tank's opening. If the issue is not solved, the leak may be due to sediment trapped in the relief port. In this case, replace the valve.

It is essential to ensure that the temperature settings are within the recommended range of about 120°F. Lowering the thermostat settings reduces excessive pressure or heat. If the temperature settings are too high, the T&P valve may regularly discharge hot water and steam.

Check the anode rod

The anode rod prevents steel tanks from rusting. Although anode rods typically last three to five years, this depends on your water quality and how much water runs through your water heater. Water softeners and acidic water accelerate the anode rod's corrosion.

A healthy anode rod reduces the wear and tear of your tank. Additionally,  it reduces the amount of sediment that collects at the bottom of your tank. If the water heater makes loud or multiple popping noises when heating up, this may imply potential corrosion of your tank's lining. Thus, it may be time to replace the anode rod.

  1. Turn off the water and fuel supply in a gas or an electric water heater.
  2. Attach a garden hose to the tank's drain and drain about 10% of the tank's volume.
  3. Locate the anode rod.
  4. Loosen the hex head. Because loosening the hex head requires a lot of muscle, we suggest asking an additional person to hold the water heater in place to avoid damaging pipes and other fittings. You can create leverage by fitting a small metal pipe section over the impact socket.
  5. Pull out the anode rod after you loosen the hex head. If the anode rod is too hard to remove, contact a professional.
  6. Install the new anode rod and firmly secure it in place. We'd recommend wrapoing the joint threads of the new anode rod with a plumber's tape.

You can also watch this video for a visual guide on how to replace the anode rod:

Final Thoughts

Close-up Of Mid-adult Male Plumber Installing Water Heater

Regularly maintain your water heater to extend its useful life and improve efficiency. Also, it is prudent to switch off the water heater if you will be away from home for at least three days; this will reduce the heater's running costs and help conserve energy.

Delve into this article to find out "How Often Does A Water Heater Run?"

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