How To Test A Thermocouple On A Water Heater

How to test water heater thermocouple

Test thermocouple/ pdfTest thermocouple and thermopile/ pdfFull service manual/ pdfHow to replace thermocoupleHow to troubleshoot pilot light going outHow to troubleshoot gas water heater Buy:Thermocouples at AmazonThermocouple adaptersGas water heater thermostats at Amazon
Mechanical gas control has thermocoupleResources:How to replace thermocoupleTroubleshoot/ service manual/ by type of gas controlHow to replace gas control valve thermostatBuy:Thermocouples at AmazonThermocouple adaptersGas water heater thermostats at Amazon
Electronic gas control has thermopile/ no thermocouple Thermopile is several thermocouples together, so voltage produced by heat of pilot is large enough to power electonics inside gas control.Resources:Test thermocouple and thermopile/ pdfHow to replace gas control valve thermostatBuy:Gas water heater thermostats at Amazon
Larger image Identify thermocouple: copper tube below gas control If gas water heater has standing pilot light, then copper tube will be connected to the gas valve.Thermocouple cannot have kinks, but copper can be rolled if thermocouple is too long.Thermocouple is finger-tight plus 1/4 turn.Overtigntening thermocouple will short electrical signal to gas control valve.Resources:How to replace thermocoupleResources for replacing thermocoupleHow to troubleshoot pilot light going outBuy:Gas water heater thermostats at Amazon
With the mechanical gas control valve thermostats, the pilot flame heats the end of a thermocouple. A thermocouple is 2 dissimilarmetals joined together that produce small current when heated. The small electrical current travels from the thermocouple though hollow tube with a wire inside, and screws into to bottom of the control valve, where it connects to an electromagnet. If the pilot light is ON, the thermocouple is working and connected correctly, and sitting in the pilot flame, then the electromagnet is energized. The electromagnet holds open the safety valve as long as the pilot flame is heating the thermocouple. If the pilot light is out, the electromagnet closesa valve, and no gas can enter gas contrtol. When pilot is re-lighted, the magnet makes audible sound that can be detected when troubleshooting.If the pilot flame is extinguished, it can take up to 180 seconds for the thermocouple to cool sufficiently for the electromagnet to de-energize and close the safety valve. The safety valve controls whether gas flows into gas control valve. If safety valve is open, then gas valve operates normally, and releases gas continually to the pilot light through the pilot gas regulator valve, and releases gas to burner through the main regulator valve when thermostat probe detects water temperature is below set point as selected on dial located on front of gas valve.With the electronic gas control valve, the pilot flame heats a thermopile instead of thermocouple. The thermopile works on same principle as thermocouple, except is larger and creates more current than thermocouple, enough current to power a circuit board inside the gas control valve. Unlike thermocouple, the current from thermopile travels to gas control valve through two wires that connect to front of gas control. The circuit board controls a series of self-check routines, error compliations of water heater operation, etc and uses electromagnets to control flow of gas that enters the gas control, and gas going to pilot and burner.See basic gas water heater partsIf no current is produced by thermocouple or thermopile, then gas to the valve is shut off until pilot is re-lit or defective thermocouple or thermopile replaced.The temperature-reading thermostat on a gas valve is located inside a copper tube that protrudes into tank and reads water temperature. When water temperature drops below selected thermostat setting, then the gas valve releases gas through the manifold tube and into the burner located in combustion chamber.How to adjust temperatureGas flows out of the burner where pilot light ignites gas. If burner is dirty, sooted or obstructed, the gas may not light immediately, resulting in unburned gas building up until it reaches the pilot flame causing explosion hazard. Sooted and dirty burner and yellow flame indicate this problem. After cleaning the burner and the combustion chamber, the gas should burn blue with bits of red and yellow.Clean burner
Thermocouple: Initial test 1) Light pilot.Hold down pilot button for 30 to 60 seconds.2) Relase pilot button.3) If pilot light goes out when button is released, then thermocouple is most likely at fault.If pilot light stays on without problems as long as gas valve is in PILOT position, but you then turn gas valve to ON position and main burner flutters and disappears within 30 seconds then 99% chance FVIR system is trippedResource:Read about TRD/ FVIR
With the pilot flame lit, turn OFF the gas supply and start to count seconds (one-one thousand, two-one thousand). Count for a full twenty (20) seconds. The pilot flame should be out.Listen carefully for a small clicking noise at the gas inlet side of the valve. If you count for the full twenty (20) seconds and do not hear a click then the thermocouple is fine.If you hear a click within the twenty (20) seconds then the thermocouple and/or gas valve are bad. Replace both the thermocouple and gas valve.
Remove thermocouple from gas valve using 7/16″ wrench. Thermocouple is finger tight + 1/4 turnSome thermocouples are reverse threaded.Test thermocouple using multimeter: Thermocouple has 2 ends: one end screws into gas valve, other end is positioned in the pilot flame.1) Make sure thermocouple is positioned correctly in pilot flame.2) Disconnect thermocouple from the gas valve thermostat using 7/16” wrench.3) Using multimeter with alligator clip leads:Attach red lead to the body (copper part) of the thermocouple.Attach black lead to the end (silver part) of the thermocouple that connects to thermostat.4) Follow instruction to light the pilot and watch voltage readings on multimeter.5) If thermocouple is good, then after 45 seconds the meter should read 12 millivolts or more.6) Clean end of thermocouple and clean inside gas valve connection before reattaching thermocouple.7) Do magnet test below. A marginal thermocouple can still produce the millivolts – but only when it’s not under load. When it’s under load (connected to the valve and trying to operate it) it might not work.
MAGNET ASSEMBLY TESTING (Robertshaw Control)Step 1. Disconnect thermocouple fromcombination thermostat/gas valve.Step 2. Connect a thermocouple adaptor(Robertshaw P/N 75036) at the thermocouple locationin the combination thermostat/gas valve.Step 3. Reconnect thermocouple to adaptor. Make certain all connectionsare tight (finger tight plus �” turn).Step 4 Using amultimeter capable of measuringmillivolts, connect onealligator clip to the set screw of the adaptor and the other alligatorclip to copper portion of the thermocouple.Step 5. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate forthree minuets.Step 6. With ameter reading of 13 millivolts or greater, rotate knob of combination thermostat/gas valve to the“OFF” position.Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” soundwhen the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out ofspecification and the combination thermostat/gas valve should be replaced.
Larger image MAGNET ASSEMBLY TESTING (White Rodgers Control)Step 1. Following the lighting instruction label on the heater, proceed to light the pilot and allow to operate forthree minutes. If the pilot will not stay lit, hold the pilot button (located on the combinationthermostat/gas valve) down during this testStep 2. Using amultimeter capable of measuringmillivolts, connect one leadusing an alligator clip to the copper sheath of the thermocouple, use the second lead of themulti meter toprobe the top terminal located at the back of the combination thermostat/gas valve.Step 6. With ameter reading of 13 millivolts or greater, rotate knob of combination thermostat/gas valve to the“OFF” position.Step 7. The magnet should remain closed for a drop of at least 6 millivolts. You will here a “snap” or “click” soundwhen the magnet opens, if you hear this sound prior to a drop of 6 millivolts, the magnet is out ofspecification and the combination thermostat/gas valve should be replaced.
Typical multimeterwill work/ might not have alligator clips.Without alligator clips you may need extra hand to keep pilot flame lit during test.Buy:Multimeters at AmazonBuy non-contact voltage tester at AmazonElectric testers at Amazon
General information about thermocouple1) CLEAR BLUE FLAME: Pilot Flame and Burner Flame must be clear blue color. Other colors such as orange and yellow indicate that burner parts, pilot orifice, and combustion chamber need to be cleaned.Troubleshoot by type of gas control2) Water heater needs oxygen for combustion. If pilot is going out, then clean air intake and get more fresh air to water heater to see if problem is solved.3) Thermocouple must sit in the pilot flame so it will stay hot.Heated thermocouple sends small electric current to gas control valve. If gas control is defective, or thermocouple is bad, or pilot blows out, or pilot flame is weak, or thermocouple has fallen loose, then gas control valve turns off pilot.4) Re-install thermocouple:finger tight + 1/4 turn. If thermocouple is too tight, the insulator is crushed and the thermocouple shorts out against the gas valve. The gas valve cannot read the current and shuts gas off to pilot.Resources:Read step to replace themocoupleTroubleshoot by type of gas control resourcesHow to replace thermocouple/ UtubeHow to replace thermcouple 2/ UtubeHow to replace thermocouple pdfBurner is sometimes removed to replace thermocouple.In that event, go ahead and clean combustion parts and combustion chamber.If LP gas is used, then manifold tube has reverse threads.Be careful of reversed threads.When re-attaching burner tubes to gas control, use fingers to start the threads.Always check pilot and manifold tubes for gas leak using soapy water.Buy:Thermocouples at AmazonThermocouple adapters
ECO located inside thermostat probe on gas controlGas water heater ECO / Energy Cut OFFIf you can get PILOT or MAIN BURNER to light – even for a couple of seconds, then the ECO if good. Otherwise replace gas control valve.ResourceHow to replace gas control valve thermostat

How to Test a Thermocouple for a Water Heater Quality 101

Is your water heater making noises? Is there a low rumbling or popping noise when you turn it on? Or is it a high-pitched whine? It’s possible that the sound you’re hearing is the sound of boiling water. When there is a significant amount of sediment building at the bottom of a tank, it can cause the bottom of the tank to overheat, which can result in the water boiling.

Multi-Meter and Milivolts

It is necessary to test thethermocouple in order to determine whether it is defective. You must first remove the thermocouple from the furnace, water heater, or gas appliance where it was originally placed before you can conduct the test on it. Once it has been removed, you will want a multimeter with the capacity to read millivolts as well as the location of the fire. Typically, a lighter will sufficient for the purpose of the test. Attach one of the alligator clips to the end of the thermocouple where the connection is made with the gas valve and one to the end of the thermocouple where the connection is made with the gas valve.

The stem does not refer to the tip or any component of the tip, but rather to the space between the point at which the thermocouple tip is connected to the gas valve and the thermocouple tip itself.

If you look at the multimeter, you should notice a reaction when the thermocouple tip heats up.

You get readings ranging from 25 millivolts all the way up to a maximum of 100 millivolts, which is quite high for this application.

Conclusion | How to Test a Thermocouple for a Water Heater

How to Test a Thermocouple for a Water Heater – Step by Step Instructions If it is more than the 25 millivolt threshold, you are in excellent shape to proceed. Preparing the thermocouple for reassembly can be simplified by lightly brushing it with a wirebrush before assembling. However, it should only be handled softly because it is easily destroyed. It is necessary to disassemble the thermocouple and then reinstall it in the pilot burner, restoring everything else to its previous state. A Thermocouple is tested in the following ways: Re-light the pilotlight, and everything should be back to normal once again.

Fluke 87-V Digital Multimeter Fluke 87-V Digital Multimeter For gas furnaces, boilers, and water heaters, the Honeywell CQ100A1013 24-inch Replacement Thermocouple is a good choice.

Gas Water Heater Thermocouple Replacement

A Thermocouple for a Water Heater – How to Test It — In this case, as long as it is greater than 25 millivolts, you are safe. The thermocouple may be cleaned by carefully brushing it with a wirebrush before reassembling the system. However, it should only be handled softly because it is susceptible to damage. It is necessary to reassemble the thermocouple and then reinstall it in the pilot burner, restoring everything else to its previous state. Thermocouple Testing Procedures– Start by turning on the pilot light, and everything should be back to normal!

Fluke 87-V Digital Multimeter is a digital multimeter that measures voltage, current, resistance, and temperature.

For use with gas furnaces, boilers, and water heaters, the Honeywell CQ100A1013 24-inch replacement thermocouple is available. Using a Thermocouple in a Water Heater: What You Should Know

Highlights

  • What is a thermocouple
  • How does it function
  • And potential problems Test a thermocouple
  • How to replace a thermocouple, including video instructions

What is a thermocouple?

Every gas water heater that operates with a pilot light is equipped with a burner assembly that is made up of the following components:

  • Thermocouple
  • Main burner
  • Main burner orifice
  • Gas supply tube for the main burner
  • Pilot burner
  • Pilot burner orifice
  • Pilot burner gas supply tube

a main burner with an orifice and a gas supply tube to feed the main burner b a pilot burner with an orifice and a gas supply tube to feed the pilot burner c a thermocouple d

How does the thermocouple work

Once you have manually lighted the pilot light, which is commonly done with a piezo igniter, it will remain lit whether or not the water is heated. If the temperature of the water inside the heater’s tank falls below the specified point, the thermostat activates and gas is sent to the main burner of the heater. The gas will then be ignited by the pilot flame. When the temperature of the water inside the tank reaches the temperature set by the thermostat, the thermostat shuts down the gas supply to the primary burner.

See also:  Tankless Water Heater How To

Thus, the electric current activates the magnetic inside the gas valve, which maintains the valve open and operational.

It can take up to a minute or two for the thermocouple to cool down and close the valve in some cases.

– Locate Plumbers in Your Locality –

Thermocouple problems

When the ignition button is disengaged, the pilot light does not remain illuminated. The possibility of a defective or loose thermocouple or thermocouple connections being the source of the problem exists. If the screw nut was too loose, it should be tightened. Because the faulty piece cannot be fixed, the only alternative left is to replace it. These components are not prohibitively costly. If you are experiencing a pilot outage, it is possible that a thermocouple is not in touch with the pilot light.

How to test a thermocouple

If the pilot light does not remain lit, check the thermocouple in the gas water heater by pressing and holding the pilot button for a few seconds. Using a multimeter equipment with the millivolts setting, measure the current flowing through the circuit. The thermocouple’s copper sheath should be linked to one probe of the meter, and the gas valve should be attached to the other probe. If the thermocouple measurement is 10 millivolts (White-Rodgers valve) or 13 millivolts (Robertshaw control valve) or above, the thermocouple is in good working order.

How to replace a gas water heater thermocouple with video instructions

  • The gas supply to the water heater should be turned off by turning off the gas control valve or the main valve. The thermocouple has two terminals on either end. One end should be connected to the gas control valve, and the other end should be connected to a pilot bracket (you can use the pliers). Take care not to damage the copper tubing throughout the process. It has a high sensitivity
  • Install a fresh element into the pilot bracket, making sure that it is firmly engaged before moving on. Using a finger tight and 1/4 turn connection, connect the other side of the element to the control valve The lighting instructions on the label must be followed in order to restart the operation.

Related

When testing a thermocouple with a multimeter, a tiny flame source should be used. The thermocouple is a critical safety element for many gas appliances, and it should not be overlooked. A thermocouple converts the heat from a flame into millivolts, which may then be used to operate a gas valve.

If the pilot burns out, the thermocouple will no longer be able to deliver the millivoltage that is necessary to keep the gas valve open, resulting in the valve being sealed to avoid a potentially hazardous gas leak.

Step 1

Take the thermocouple out of the appliance and set it aside. Make certain that all safety procedures are followed. Check to see that the multimeter you’re going to use can read both ohms/resistance and millivolts simultaneously.

Step 2

Select a test to use in order to evaluate the thermocouple. The open circuit test, the closed circuit test, and the resistance test are the three most commonly utilized tests. While all three tests are helpful, the closed circuit test will clearly reveal whether or not the thermocouple is performing properly under load, and it is frequently the first test that is performed.

Step 3

On your multimeter, choose either the ohms or the resistance reading. Place one test lead on the side of the thermocouple and the other on the end of the thermocouple that screws into the gas valve to complete the circuit. The presence of a tiny resistance measurement on the multimeter should indicate that the thermocouple is in correct continuity. Many multimeters additionally provide an auditory alarm that indicates whether or not the measurement is continuous. A “OL” signal on the multimeter shows that the thermocouple does not have continuity and, as a result, it is unable to function.

Step 4

To do an open circuit test, set your multimeter to millivolts on the dial. Connect the test leads of the multimeter to the side of the thermocouple and the other to the end that will be entering the gas valve to complete the testing procedure. Light a lighter or other heat source with a flame at the other end of the thermocouple and place it near the thermocouple. Residential gas appliances, such as fireplaces, water heaters, and furnaces, are equipped with thermocouples that operate at 30 Millivolts.

Whenever the thermocouple voltage falls below or hovers around the 20 millivolt level, it indicates that it has to be replaced.

Step 5

Use the thermocouple adapter to conduct a closed circuit test in order to determine the genuine performance capabilities when under load. When crocodile clips are secured to the test leads, it is much easier to do this test successfully. To begin, attach the thermocouple adapter to the gas valve in the same location as the thermocouple. The thermocouple should then be attached as normal, with the difference that the end that would normally screw into the gas valve should instead screw into the adaptor.

Step 6

Turn on the appliance and attach a crocodile clip from the multimeter to the side of the thermocouple with the other hand.

Attach the other crocodile clip to the screw that protrudes from the side of the adapter. (See illustration.) Between 12 and 15 millivolts should be recorded as a reading for this test. When the thermocouple’s voltage is less than 12 millivolts, it indicates that the thermocouple is malfunctioning.

How to Tell If a Thermocouple Is Bad

The image was provided by: GregorBister/E+/GettyImages

In This Article

  • The pilot light comes on but does not remain on
  • Consider the following before blaming the thermocouple: Check the thermocouple’s performance.

Unless you have an automatic gas water heater, a gas wall heater, or any other equipment that has a gas burner that needs to turn on and off, you have a thermocouple in your home or office. As with the Olympic torch, it is an inherently dependable device when used in conjunction with a standing pilot, which is a small flame that continues to burn as long as the appliance is in use. The thermocouple’s function is to maintain the flame of the pilot. It accomplishes this by supplying a very little electric current to a sensor on the gas valve, signaling to the valve to remain open until the current is stopped.

This is due to a phenomena known as the Seebeck Effect, which is responsible for this.

A variety of different factors can cause the pilot to go out; thus, if you’re having difficulties keeping the pilot lit, it’s possible that the thermocouple isn’t the source of the problem.

The Pilot Lights But Won’t Stay Lit

Unless you have an automatic gas water heater, a gas wall heater, or any other item that has a gas burner that needs to turn on and off, you have a thermocouple in your life. As with the Olympic torch, it is an inherently dependable device when used in conjunction with a standing pilot, which is a small flame that continues to burn as long as the appliance is in operation. The thermocouple’s function is to maintain the pilot light’s illumination level. When a little electric current is sent to a sensor on the gas valve, a signal is sent back, signifying that the valve should remain open.

A phenomenon known as the Seebeck Effect has caused this to occur as a result of its occurrence.

A variety of different factors can cause the pilot to go out; thus, if you’re having issues keeping the pilot lit, it’s possible that the thermocouple isn’t the source of your problems.

Try This Before Blaming the Thermocouple

The pilot flame must be large and very hot in order to heat the thermocouple to the temperature required in order to create enough voltage to activate the gas valve. A common cause of thermocouple failure is simply a distance between the thermocouple probe and the flame. If there is enough space in your palm for you to reach in and relocate the probe closer to the flame, you can eliminate this option. By shutting off the gas, unscrewing the pilot tube from the gas valve, and pushing compressed air into the tube, you can rule out blockages in the pilot tube as a probable source of the problem.

  1. The design of thermocouples for gas appliances is standard.
  2. A thermocouple is composed of a probe attached to an aluminum tube that screws into a port on the gas valve.
  3. You may do this yourself using a multimeter, but you may need someone to assist you in keeping the pilot flame blazing while you are doing it.
  4. Set the multimeter to read millivolts, then light the pilot and instruct your assistant to hold the gas control knob in place to keep the flames burning.

If the probe has gotten hot enough after approximately a minute, connect one lead to the shaft of the thermocouple and the other lead to the connection when you’re confident it’s hot enough. If the measurement is less than 25 millivolts, the thermocouple is faulty and should be replaced immediately.

How to Test the Thermocouple on a Gas Tank Water Heater

It’s frequently remarked that “small things may make a great impact,” and this is certainly true. This is true in a variety of aspects of life, yet the term makes us think of water heaters specifically. Tank water heaters are often used in homes and may contain 40 to 50 gallons of water while weighing well over 100 pounds when fully loaded. However, because to a little component known as a thermocouple, this enormous appliance has the potential to quit operating unexpectedly. This means that if the thermocouple in the gas water heater malfunctions, the device will be disconnected from the gas supply.

What does the thermocouple do?

The thermocouple is a safety component that communicates with the pilot burner and the gas control valve to ensure proper operation. When the pilot flame is lighted, the thermocouple employs a tiny electrical current to open the gas valve, allowing gas to flow into the main burner of the water heater and heating it. In contrast, if the pilot light is turned out, the thermocouple will cut off the natural gas flow that is supplied through the gas valve. What is the significance of this? If the pilot is not lit (or is malfunctioning) and the gas valve is allowed to remain open, natural gas can escape from the water heater and into the residence, posing a serious health hazard to the occupants.

Even if the pilot light is operating properly, this inhibits the gas valve from opening properly.

Therefore, it is critical to detect a malfunctioning thermostat so that the component may be replaced and your water heater can resume operation.

How to test a thermocouple

An electrical multimeter (also known as multitester) is required for the testing of thermocouples. A multimeter is a compact device that can conduct numerous electrical measurements such as voltage, current, and resistance. Furthermore, you must know the sort of gas valve you have, either a White-Rodgers or a Robertshaw gas valve. Once you have obtained this gadget, carefully follow the instructions below.

  • Continue to hold down the pilot button
  • Set the millivolts setting on the multimeter. Place one probe of the multimeter on the copper section of the thermocouple and the other probe on the gas valve
  • Then, repeat the process with the second probe. Unless the thermocouple reading on the multimeter is more than 10 millivolts for a White-Rodgers valve or greater than 13 millivolts for a Robertshaw valve, the thermocouple should be changed.

Installing a new thermocouple

We do not recommend that you attempt to install a new thermocouple on your own unless you have substantial plumbing knowledge first. Because this little, fragile component interacts with electricity and natural gas, even the smallest error may be extremely hazardous. Additionally, if the thermocouple is not properly placed, it may result in damage to your water heater. The more prudent and safest course of action is to contact the experts at Emergency PlumbingSolar. We are pleased to provide service to the whole island of Oahu.

No Hot Water? Restore It Yourself

Your gas water heater’s burner chamber has what’s known as a thermocouple, which is a little metal cylinder that sits directly in front of the pilot light.

The thermocouple is a safety device that detects when the pilot light is on and has to be replaced. If the pilot light goes out, the thermocouple sends a signal to the gas valve, which keeps the valve closed until the pilot light returns.

A worn out thermocouple is one of the most common gas water heater problems

Thermalcouples wear down over time, causing the pilot light to go out, the burner to not fire, and the lack of hot water to result. First, try re-igniting the pilot by following the instructions on the tank’s side panel. It is possible that the thermocouple is defective if the pilot ignites but the flame goes out as soon as you release the button after holding it for 60 seconds. It is feasible to change the thermocouple without having to disassemble the burner assembly, and many repair technicians do so.

  • Even though this work is straightforward, you should not do it unless you are familiar with how to turn off the gas to the water heater and are confident in your ability to relight the pilot.
  • A wide variety of thermocouples for water heaters may be found at most hardware stores and home improvement centers.
  • Then purchase a replacement in the same size.
  • If your water heater does not appear to be the same as the one seen, contact a repair service.
See also:  How Much Does A Water Heater Permit Cost

Water Heater Thermocouple: What You Need to Know

In gas-powered water heaters, a thermocouple is a critical component that must be properly installed. If your heater is fuelled by natural gas or propane, a thermocouple is required to guarantee that it performs in an efficient and safe manner. The information in this article will assist you in gathering the knowledge you want, whether you are experiencing problems with your water heater or simply want to learn more about this important component. Many people believe that if the thermocouple fails, it is essential to replace the complete water heater; however, in reality, they are reasonably simple to fix and are not prohibitively expensive.

What is a Water Heater Thermocouple?

Gas-powered water heaters rely on a thermocouple, which is a critical component in their operation. A thermocouple is required if your heater is fuelled by natural gas or propane to guarantee that it functions securely. The information in this article will assist you in gathering the knowledge you want, whether you are experiencing problems with your water heater or simply want to learn more about this important appliance. Despite the fact that many people believe that if a thermocouple fails, it is required to replace the complete water heater, thermocouples are actually reasonably simple to fix and not prohibitively expensive.

It is our goal to educate you about the operation of a thermocouple, how to diagnose a problem, and even how to replace the component if it becomes damaged or defective.

Why Does a Water Heater Thermocouple Go Bad?

When the thermocouple is correctly functioning, it makes advantage of a phenomena known as the Seebeck Effect. This is where two metal rods work together to generate a little electrical current, which keeps the gas valve on your water heater open. A problem with the two metal rods of your thermocouple’s voltage generation is the most likely reason of its malfunction. Despite the fact that in certain circumstances the problem may be resolved, most homeowners opt to replace the thermocouple because they are so inexpensive to begin with.

Thermocouple Location

The thermocouple is a component of the water heater’s burner assembly, and it is located next to the pilot light on the burner assembly. It is kept in place by a handful of clips once it has been inserted into a bracket. In this case, the thermocouple line is linked to the gas control valve, which is positioned on the exterior of the tank and is located outside the heater.

Difference Between a Thermocouple and a Flame Sensor

As previously stated, your water heater may employ a flame sensor rather than a thermocouple to regulate the temperature. Despite the fact that these names are frequently used interchangeably, they are technically distinct. When it comes to contemporary water heaters that employ an electronic controller, a flame sensor is often present, whereas thermocouples are typically found on older heaters. While these distinctions are important to notice, they are not particularly significant in the grand scheme of things.

Troubleshooting a Faulty Thermocouple

If your thermocouple is malfunctioning, the first sign that you may notice is that you are not getting hot water. Because a faulty thermocouple will cause the gas valve to be shut off, your water heater will be unable to provide the necessary resources to heat the water in the storage tank. If your thermocouple is not working properly, the pilot light will not illuminate. Trying to light your pilot and finding that it won’t remain lighted might be a sign of either a malfunctioning thermo cutoff switch or a bad thermocouple.

How to Test a Thermo Cutoff Switch

Located in the front of the combustion chamber, the thermo cutoff switch prevents the engine from overheating. Temperatures in the chamber that exceed 160° to 180°F are meant to cause the thermocouple to be effectively shut down by the device. The thermo cutoff switch is linked in series with the thermocouple in order to prevent overheating. If the temperature in the combustion chamber rises over a certain point, the switch will trip, cutting power to the valve and shutting it down. Some thermal cutoff switches feature a reset button, while others will automatically reset, and still others require a one-time fuse to maintain its functionality.

It is vital that if you notice a strong gas smell at any time, you immediately shut off the gas supply and contact a professional plumber to assist you in determining the source of the smell. This test will necessitate the use of a digital multimeter. Here’s what you should do:

  • To ensure that the electrical connections are secure, remove the cover and examine them closely: Check the thermal cutoff switch for a reset button if there isn’t one already. If necessary, perform a reset. Set the multimeter to the ohms setting in order to check the switch for continuity (to determine whether a continuous electrical current may travel through it). Disconnect the wires from the switch and set the probes on the terminals
  • Then, reconnect the wires. If the multimeter displays OL, or open loop, this indicates that there is no continuity and that the switch must be replaced.

If the thermal cutoff switch is in fine working order but the pilot still won’t remain lighted, the thermocouple should be checked.

How to Test a Thermocouple

You’ll need to ignite the pilot and check the voltage in order to accomplish this. An adjustable wrench as well as a multimeter will be required. Here’s what you should do:

  • Make sure the volts DC option is selected on the multimeter. The thermocouple should be disconnected from the gas control valve by using an adjustable wrench
  • Assign the probes to the copper line and to the thermocouple’s termination
  • Light the pilot and press the button till it flashes
  • As the thermocouple heats up, the voltage should begin to grow over the course of the following several minutes. In an open circuit test, a properly functioning thermocouple should read between 20 and 30 millivolts. Depending on the measurement, the pilot may have problems keeping lighted if the voltage is less than 20 millivolts. On the thermocouple, it is possible that a build-up of carbon has developed, which is acting as an insulator. Even while you may remove the thermocouple and clean it, most of the time it is preferable to simply replace it with a new one.

How to Clean a Thermocouple

The following steps will guide you through the process of cleaning your thermocouple if you have established that it is receiving a reading of less than 20 millivolts.

  • Close the gas intake valve and remove the water heater burner component from the water heater. Before you can remove the burn assembly, you’ll need to separate the thermocouple, main supply tube, and pilot supply tube from the system. Using emery cloth sandpaper, gently clean the thermocouple. To clean the ends of the thermocouple’s metal rods, sand them and then wipe them off with a lint-free cloth. Before lighting the pilot, reconnect the burner assembly and open the gas input valve.

You may try using your multimeter again to see if you can obtain a higher millivolt reading this time, but if the problem persists, your best bet is to replace the thermocouple altogether.

How to Replace a Thermocouple

If you’re a do-it-yourselfer, changing the thermocouple in your water heater should be a piece of cake. It’s not difficult, and it’s also not expensive at all! You will, however, be working with a live gas line, so proceed with utmost caution during the replacement operation to avoid injury. If you’re at all concerned about dealing with natural gas appliances, we strongly advise you to get a professional to complete the job for you instead. Before you begin, you’ll need to determine what size thermocouple you’ll need for your water heater.

Thermocouple for Honeywell Heat Exchanger

Step-by-Step Instructions

  • Replacement of your water heater thermocouple is a do-it-yourself project if you are handy with tools. You won’t have any problems, and it’ll be quite affordable. You will, however, be working with a live gas line, so proceed with utmost caution during the replacement operation to avoid any accidents. If you are at all concerned about dealing with natural gas appliances, we strongly advise that you get a professional to do the job for you. It is necessary to first determine the appropriate size thermocouple for your water heater prior to proceeding. If you’re unsure, it’s preferable to buy a longer thermocouple and gently coil the extra within the panel. Thermocouple for Honeywell Heat Exchangers

Watch the Video

Documentation Download Documentation Download Documentation Generally speaking, a thermocouple is a safety device that aids in the regulation of gas supply in gas-fired furnaces. When it ceases to function, the pilot light on the furnace is turned off as well. To do a basic test, switch on the pilot light again and see whether it works. If you’re still not sure or don’t have a working pilot light, you may use a multimeter to check the thermocouple’s resistance. The information obtained may be used to keep your furnace in good working order and your house safe and toasty throughout the whole year.

  1. 1Assign the pilot light controls to the gas valve where they belong. Locate your home’s gas tank, which is usually located in the basement or on the lowest floor. The pilot light is controlled by a tiny box with dials in black, red, or white that may be found on the wall. A metal pipe will also be flowing into it, carrying the gas supply
  2. 2Turn on the pilot light for 30 seconds while the pilot light is on. The dial on the gas valve that controls the flow of gas will be labeled. Set the dial to the “Pilot” position. To switch on the pilot light, press the reset button located on the top of the box. For 30 to 60 seconds, press and hold the reset button to give the thermocouple enough time to heat up. Advertisement
  3. s3 To see if the pilot light turns off, press and hold the button until it does. After the reset, the pilot light should remain illuminated. If it goes out, it is a sign that the thermocouple is no longer functional. You have the option of replacing it immediately or removing it to undertake a more accurate test
  4. 4 To retest the thermocouple, turn off the gas supply and reconnect it. In order to double-check if the thermocouple is at fault, turn the dial until you reach the “Off” setting on the display. To turn off the gas supply, turn the dial clockwise. It is also feasible to follow the metal tubing that leads to the pilot light controls if this is not possible. It will be equipped with a little valve on the top. Counter-clockwise rotation of the valve will shut off gas supply
  5. 5count to 20 and wait for the pilot light to go out. Because the gas supply has been cut off, the pilot light must dim. If the flame is still burning after 20 seconds, the gas supply has not been shut off yet. 6 Make minor adjustments to the dial and valve to try again. Keep an ear out for any clicking around the gas valve. There’s a clicking sound that emanates from the junction of the gas supply pipe and the gas valve box. During the first 20 seconds, if you hear clicking, it is a warning that your system requires repair. It’s possible that both the thermocouple and the gas valve are malfunctioning. Make use of a professional
  • Only specialists are equipped with the necessary parts and legal authorization to repair a gas valve. When they do this, they will need to replace the thermocouple.
  1. 1 The thermocouple should be located on the gas control thermostat. The thermostat for the gas control system will be located on the outside of the gas tank, potentially on a neighboring wall. Check the side of the thermostat for a flexible tubing that has been connected into the wall. It is frequently painted in silver or crimson.
  • The tube links to the gas valve, which is located below the pilot light, and it is made of brass.
  • 2With a wrench, pry the thermocouple out of the circuit. Return to the thermostat and look for the metal nut that is holding the thermocouple in place with your fingers. Using a 7/16-inch (11-millimeter) wrench, spin the nut counterclockwise to release the thermocouple. Start by turning on the multimeter. The sort of multimeter with red and black clamps is the most convenient to use for this particular test. Turn on the power switch for the multimeter. Change the measurement to Ohms by turning the settings dial to the right. The Ohms sign is represented by a horseshoe shape. An electrical resistance meter is used to measure electrical resistance.
  • Consult your multimeter’s owner’s manual for more detailed instructions on how to use it.
  • 4 Holding the leads of the multimeter together will allow you to test it. Separate the black and red clamps, or leads, by holding them apart. When you aim them in different directions, the meter should remain at infinity on the left side of the screen. Watch as the meter goes from 0 to 5 as you connect the leads together. Connect the thermocouple leads to the leads on the thermocouple. The top end of the thermocouple should be clamped with the black lead. This is the portion of the thermostat that you removed previously and which seems to be a spherical nub in shape. Take the red lead and attach it to the tube just below the nut on the thermocouple to prevent it from moving. The tube is either silver-colored or copper-colored, and the clamp should be placed directly to it
  • Otherwise, the clamp will not work. 6 In order to begin the test, turn on the pilot light. First, switch the multimeter to the volts setting. Turn on the pilot light by turning the knob on the gas valve on the tank. This is generally accomplished by rotating the knob to the “Pilot” position and then pressing and holding down the reset button located on the top of the gas valve box.
  • 4 When you hold the leads together, you may test the multimeter. The clamps or leads in the colors black and red should be separated. As long as you aim them in opposing directions, the meter should remain at infinity on the left. Watch as the meter changes from 0 to 5 by connecting the leads together. To connect the thermocouple, connect the leads together. The top end of the thermocouple should be clamped using the black lead. There’s a spherical nub on the end of this piece, which you removed from the thermostat previously. The red lead should be connected to the tube below the nut on the thermocouple. In this case, the tubing is either silvery or coppery in color, and it should be clamped directly to the wall. 6 To begin the test, turn on the pilot light. First, switch the multimeter to volts. By turning the knob on the tank’s gas valve, you may turn on the pilot light. For the most part, this is accomplished by rotating the knob to the “Pilot” position and then pressing and holding down a reset button located on top of the gas valve box.
  • 7 Make sure the thermocouple reaches a voltage of 25 millivolts. Allow one minute for the thermocouple to warm up. After one minute has passed, check the display on the multimeter. If it is displaying millivolts, the reading should be between 25 and 35 millivolts. If it merely displays volts, check for the meter to go slightly over zero
  • Otherwise, leave it alone.
  • Inspect the thermocouple to ensure that it is reaching 25 millivolts. Allow a minute for the thermocouple to warm up before proceeding. Check the display of the multimeter after one minute has passed. The millivolts displayed should be between 25 and 35 if the device is capable of displaying such information. It is important to notice if it just displays volts and whether or not the meter has moved significantly over zero.
  • Another alternative is to contact a heater repair technician in your area. This is an excellent alternative if you require assistance with the repairs or think that your system is experiencing additional issues, such as a defective gas valve.
See also:  How Hot Should Water Heater Be Set

Alternatively, you might contact a local heater repair service. In the event that you require assistance with the repairs or think that your system has other issues, such as a malfunctioning gas valve, this is an excellent choice.

  • Question In the event that my thermocouple has been covered with a white powder, what should I do? The owner of G and R Appliance Repair in Los Angeles, California, Gevorg Grigorian is an Appliance Repair Specialist and the owner of G and R Appliance Repair. Gevorg has over 12 years of expertise in appliance repair for both residential and commercial customers, as well as heating, ventilation, and air conditioning (HVAC) installation and maintenance. Gevorg graduated from California State University-Northridge with a Bachelor of Science in Business Administration and Management. Expert Answer from an Appliance Repair Expert

Fill in the blanks with your question and email address to be notified when it is answered.SubmitAdvertisement200 characters remaining

Video

  • When replacing the thermocouple, proceed with caution. It is possible that overtightening it will prevent the flame from igniting. A blue pilot light flame indicates a healthy pilot light. A flame that is yellow or orange indicates that the system needs to be cleaned. If the surface of your thermocouple is coated with a white, chalky substance, this might signal that it is not working correctly.

Advertisement

  • Gas valves are permanently damaged and cannot be fixed. If you feel that this is the source of the problem rather than the thermocouple, see an expert.

Advertisement

About This Article

Thank you to all writers for contributing to this page, which has been viewed 52,385 times so far.

Did this article help you?

T he thermocouple is a safety device in gas water heaters which determines if the pilot light is lit. The heat generated by the pilot light flame generates millivolt current in the thermocouple, which in turn energizes a magnet, which in turn allows the gas control valve to function. If the pilot light fails to illuminate, the thermocouple will not generate any power, and the magnet will close the valve, preventing the gas from flowing. A frequent indication of a defective thermocouple is that the pilot light will not remain illuminated for long periods of time.

  1. By removing the inner and outer doors, you may examine the thermocouple’s operation.
  2. The thermocouple’s tip should be smooth and free of corrosion, and it should not be bent.
  3. When there is no flame, it may be necessary to have an aid to examine the location in the flame.
  4. While keeping an eye on the flame, press the pilot light button.
  5. If the thermocouple is not in the appropriate position, cut off the gas supply and relocate the thermocouple to the proper location.
  6. In addition, make sure that the thermocouple connection to the gas valve is secure.
  7. The thermocouple should be replaced in order to restore electricity to operate the gas valve and keep the flame burning.

If the problem persists, it is possible that the gas valve is the source of the problem itself. Because of the high expense of replacing the gas valve, it may be more cost effective to replace the complete water heater, particularly with older models.

7 Reasons Your Water Heater Pilot Light Keeps Going Out

There is nothing more inconvenient than stepping into a frigid shower to begin a chilly day. It’s possible that you’ve recently found that the pilot light is constantly going out. Thousands of consumers are dissatisfied with their water heaters, which fail to function properly only a few months after installation. Is it usual for your water heater to go out on you in the middle of the night? No! Your heater should be able to easily reach the 10-year milestone without experiencing any serious problems.

Take a look at these beautiful water heaters in Phoenix.

What Is The Pilot Light?

The Pilot Light is the heart of your water heater, and it controls the flow of water. Essentially, it is a little blue flame that produces heat by burning petroleum gas. There would be no heat and, hence, no warm water if this flame were not present.

So, What Are The Reasons Your Water Pilot Light Keeps Going Out?

Not only will we identify the potential issues, but we will also provide you with solutions to those issues. Please take notice of the following: Check to see whether your water heater is still covered by the manufacturer’s warranty. If this is the case, it should be returned to the supplier or manufacturer for repairs or complete replacement. Precautionary measure: To begin, shut off the main gas supply valve to prevent potentially fatal gas leaks. Wait 5 minutes for the heat and gas to dissipate before continuing.

1. An Unclean Pilot Tube

It’s a problem that practically all water heaters have at some point. Please don’t be concerned, your heater is in perfect working order. It’s simply a buildup of dirt. The Pilot tube is responsible for supplying gas to the pilot light in order for it to burn. if the tube becomes blocked with dirt or other particles, the flame will go out. It is possible that the tube is partially blocked and only supplying a little amount of gas for combustion—which explains why your pilot light keeps going out.

To gently clear the tube, use a thin needle to poke it with.

You must be patient during this process.

Place the container back where it belongs and turn on your water heater.

2. A Dirty Thermocouple

In the case of a water heater, the thermocouple serves as its brain. It is in charge of shutting down the gas valve when it detects that the pilot light has gone out. Because the pilot light produces an electric current, the thermocouple is activated when this current is present. It serves as a safety measure, preventing gas leaks from occurring. As a result, a filthy thermocouple might be the source of your water pilot’s inability to function properly. When a coating of filth and dust accumulates on the surface of a thermocouple, the electric current cannot reach it.

On a chilly Monday morning, there is no hot water. The solution: You’ll have to perform some more cleaning this time. To begin, shut off the main gas supply valve and allow the thermocouple to cool before proceeding. Using a new piece of sandpaper, scrape away all of the filth and grime.

3. A Kinked Thermocouple

In the case of your water heater, the thermocouple serves as its brain. After detecting that the pilot light has gone out, the gas valve must be shut off. Because the pilot light produces an electric current, the thermocouple is activated when this current is detected. A safety device that prevents gas leaks is installed. A dirty thermocouple might thus be the source of your water pilot’s inability to function properly for extended periods of time. In order for the electric current to reach the thermocouple, it must first pass through a layer of filth and dust.

On a brisk Monday morning, there is no hot water.

To begin, shut off the main gas supply valve and allow the thermocouple to cool before proceeding further.

4. A Broken Thermocouple

So, you’ve cleaned and straightened your thermocouple, but your water pilot continues to fail despite all of your efforts. You should be prepared to accept the possibility that your thermocouple is faulty at this point. Perform a diagnostic test with a multimeter on your thermocouple first, though, before you give up on it. If the voltage delivered by your thermocouple is significantly less than 20MV, then the device is almost certainly damaged and should be replaced immediately. The Solution: If the multimeter reading is near to, but not exactly at, 20MV, you can adjust the thermocouple closer to the pilot light to save energy.

5. Flex Tube Issues

Flexible tube is a long tube that links the gas controller to the burner, which contains the pilot light, thermocouple, and other components. If the flex tube is broken or blocked, the gas will not be provided to the burner for combustion to take place. Flex tube failures, on the other hand, are not as prevalent as thermocouple failures. This is why you must first inspect and ensure that your thermocouple is in excellent working order before turning your attention to the flex tube. The Solution is as follows: Straighten any kinks in the flex tubing that have formed.

Leaks in the gas line will lower the amount of gas that reaches the burner.

6. A Faulty Main Control Valve

It’s possible that you’ll never run into this situation again. We recommend that you examine the pilot tube, thermocouple, and flex tube before attempting to modify or repair this piece of equipment. The Main Control Valve Unit has a very low failure rate. However, don’t count it out just yet; it’s possible that it’s the source of your water pilot’s incessant failure. Main Control Valve: This valve is in charge of regulating the gas and water pressures of the water heater. Your water heater’s heart and soul is the thermostat.

When the gas is ignited, the main valve is fully opened, allowing for a consistent stream of gas to be provided.

A malfunctioning main control valve will cause the gas valve to close abruptly, cutting off the gas supply and resulting in a feeble flickering flame. The following are signs of a defective main control valve:

  • A malfunctioning pilot button that does not illuminate after being pressed
  • A malfunctioning control knob
  • When the water temperature exceeds the stated range, you will feel extremely hot water.

Unresponsive pilot button that does not appear to respond to the push of the button. Control knob that is not working properly. When the water temperature exceeds the stated limit, you will feel extremely hot water;

7. Poor Electrical Wiring

When it comes to electric water heaters, this is generally a concern. The fact that you should always engage a professional to install your water heater is one of the main reasons for this. If your water heater suddenly stops working, this is the first indication of a defective electrical system. The Solution: Turn off your water heater as soon as possible and contact a professional. Please do not tamper with the electrical wiring system.

Our Final Word

If all of your methods fail and your pilot light continues to go out, it’s time to call in the heavy guns (the professionals). We’re aware. We’re aware. The services of technicians are not cheap, but at the very least you will have greater confidence in the repairs. In addition to that, we are all aware of the dangers associated with electricity and natural gas. Your safety is of the utmost importance. Did you find this information useful? Check out Why Are Trane HVAC Units So Popular? for more information.

Leave a Reply

Your email address will not be published.