Hot Water Heater Sensor Failure (Symptom, Test, Repair Cost)

whirlpool, honeywell, gas, electric, reliance, ao smith hot water heater temperature sensor failure

The sensor is important because it uses a small electric current to manipulate the gas valve. A defective sensor cannot signal the gas control valve. This prevents the heater from warming the water to the temperature you require.

Hot Water Heater Sensor Failure Meaning

You can tell that the water heater has a problem because the water is either too hot or too cold. But other factors can produce similar results, including a defective pilot light that refuses to stay on, insufficient oxygen, debris, etc.

Hot water heater sensors are not immune to failure. This water heater manual mentions heat sensors. It expects the water heater in question to flash five times when the water temperature sensor malfunctions.

They also expect the consumer to respond by replacing the thermostat or gas control valve. This tells you that water heater sensors can fail. And if they do, you can either fix or replace them, depending on the severity of the problem.

To understand why homeowners replace malfunctioning heat sensors, you have to understand the function the thermocouples play:

1). Thermocouples work in tandem with the pilot light.

2). The thermocouple keeps the gas valve open. It sits over the flame, generating a current that controls the gas valve.

3). The thermocouple will turn the gas supply off if the pilot light keeps going out.

4). If the thermocouple malfunctions, it can’t tell whether the pilot light is on or off. As such, it can’t control the gas supply.

You cannot blame every problem that occurs on the sensor. Inspect the water heater sensor before you act. Don’t assume that the sensor is faulty until you test the component with a multimeter.

What Are The Signs Your Hot Water Heater Sensor Is Going Out?

The temperature will tell you everything you need to know. For instance, water heaters are supposed to raise the temperature of the hot water running through the pipes. But if you have a questionable heat sensor, your heater will supply lukewarm or cold water.

In other words, the water is hot enough, but it doesn’t last long.

But cold or lukewarm water is the least of your worries. Most people can tolerate cold or lukewarm water. The same cannot be said for scolding hot water.

Some heaters go too far. Because the heat sensor has failed, the temperature will rise to unsafe levels.

Basically, you can use the temperature to diagnose a heater’s health.

If you observe any of these issues, talk to a professional. They will troubleshoot the heat sensor. But again, the heat sensor is not the only factor that can cause these issues.

You have to keep an eye out for other problems, including low water pressure, leaks, broken heating elements, loose connections, etc. Water heaters are just like any other appliance.

They have symptoms that any savvy homeowner can use to diagnose them.

Do you hear strange noises? Are the electrical connections sparking? Does the water smell?

Your technician will ask all these questions and more to get a better idea of the problem.

If you have the technical expertise to diagnose and repair the water heater, check the following elements before you blame the sensor:

1). Look at the plumbing. Are the pipes rusted? Are they clogged? Is the pressure poor?

2). Test the hardness of the water. If the old sensor stops working because of the accumulated sediment, the new sensor will suffer the same fate, especially if the water is harder than usual.

3). If your heater uses gas, is the gas supply working? If you have an electric model, is the power on? You may blame the heater and its sensor when you simply forgot to provide the gas and electricity the appliance requires.

4). How old is the appliance? Water heaters have an average lifespan of 12 years. You can raise or lower that figure depending on your maintenance routine.

But if you bought the heater more than a decade ago, or the heater had been in use for more than ten years before it entered your home, you have to consider the possibility that the appliance has reached the end of its lifespan.

You can replace a faulty heat sensor, but the temperature issues may persist because all the other components have reached the end of their lifespans. This is where a technician enters the picture. They can inspect every aspect of the heater to determine whether it will continue to work or if you’re better off getting a replacement.

Why These Sensors Failed?

  • The sensor accumulated dust or debris
  • The sensor is bent or broken
  • You have a loose connection
  • The sensor is worn out, or it has an internal fault

What To Do If Water Heater Sensor Is Failed?

You can power cycle the water heater. This is where you turn the gas control knob off. Give it a few minutes and light the pilot. If you’re lucky, the unit will come on. If it doesn’t, inspect the gas valve. Don’t replace it without testing the temperature sensor.

How Do You Test A Hot Water Heater Temperature Sensor?

You can test the sensor with a multimeter. Your approach will depend on the type of heater. Appliances with a standing pilot attach the thermocouple and pilot to the burner assembly. But if your heater has an electronic ignition system, find the pilot, thermocouple, and electronic igniter on the burner assembly. Either way, you have to test the sensor with a multimeter:

1). Start by buying pin probes. You can’t just force conventional probes into the small holes. You will ruin the pins.

2). You can’t access the sensor without disassembling the gas valve. If you can’t even disassemble the gas valve, you should leave this task to a technician. Heaters are dangerous to laypeople.

3). Connect the multimeter to the pins on the plastic connectors. Again, you should buy pin probes that fit the pins on the plastic connectors. You don’t want to damage them. Push the pin probes into the center and outside holes.

4). Look at the resistance. Compare the readings to the manufacturer’s chart. If you check the manual or the manufacturer’s website, it will show you the resistance you can expect. Don’t forget to measure the water temperature.

You have to compare the resistance at different temperatures to the manufacturer’s information. Perform these tests while the sensor is still connected to the backplate. You should also ensure that the multimeter is set to ohms.

Be specific with your readings. Don’t round off or make estimates. Otherwise, the manufacturer’s chart won’t help you. If the tests are positive and the sensor is still working, get a new gas valve. But if the sensor’s readings do not match the information on the manufacturer’s chart, you need a new temperature sensor.

Can I Repair It or Do I Need To Replace It? How Much Does It Cost?

If the sensor is dead, you have to replace it, a process that involves the following:

  • Don’t tamper with the heater until you disconnect the gas connections
  • To get to the thermocouple and ignition, you have to remove the burner assembly manifold cover, a process that requires the consumer to pull the fasteners and screws out.
  • Be careful as you pull the cover plate gasket off. Otherwise, you may require a replacement.
  • Twist the thermocouple as you pull it from the bracket. Apply some pressure without bending the connection. Depending on the situation, the thermocouple may force you to cut it
  • Push the new thermocouple into the bracket and replace everything you removed.

If you’re still dissatisfied with the water temperature, you can take other measures to fix the heater. For instance, once you take the burner assembly off, take a moment to clean the burners.

Remove any soot or debris you see. If that doesn’t solve the problem, check the water tank. Deposits will accumulate over the years, compromising the sensor’s sensitivity to temperature changes.

Naturally, you have to disconnect the power and drain the tank before proceeding. Ultimately, you may require the services of a plumber, especially if the water has a bad smell. An expert can check your home’s piping.

A new water heater sensor can cost you $200 or less. But replacing the pipes in a large home can cost you $10,000 or more. Fortunately, this is the last resort.

Related post:

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts