How to Clean the Thermocouple on a Water Heater

To clean the thermocouple in a water heater is an important maintenance procedure. If you don’t, it will eventually prevent the water from heating up. Hence, hot water supply will cease.Today we’ll show you how to clean the thermocouple on your water heater to avoid this inconvenience.


What is a Thermocouple?

Sparing you the technical jargon, a thermocouple is an electrical device used to sense changes in temperature. Thermocouples are used in a wide variety of commercial and industrial applications because it has the advantage of not needing external power or excitation over other forms of temperature measurement. A thermocouple can be found in diesel engines, gas turbines, kilns, gas water heater, temperature sensor in thermostats, etc. 


how to clean the thermocouple in a water heater


Corrosion and buildup are some of the things that can affect a thermocouple. They can prevent power from reaching the pilot light, thus the water won’t heat up.

Though changing the thermocouple is not a difficult task nor is it costly. But before you conclude, first be sure it not merely dirty. If it is, a good clean up can get it back to working condition.

That is where we come in today. To tell you how to clean the thermocouple on a water heater.

It’s great you’re still with us! Now let’s get on to the process involved.




How Does a Thermocouple Work?

A simple explanation of how a thermocouple works is as follows: A thermocouple is made up of two different electrical conductors that form an electrical junction at one end. It produces a milivolt of temperature-dependent current when one of the conductors is heated which is interpreted to measure temperature. This process is called the Seebeck Effect. One limitation of thermoucouples is their accuracy. It’s hard to achieve a system error of less than one degree Celsius.



Steps to Clean the Thermocouple on your Water Heater

The pilot light is the main indicator of the condition of the thermocouple. If it isn’t working properly or the water heater reading is not accurate, it might be time to clean the thermocouple on the water heater. To clean the thermocouple on a water heater follow these steps to bring it back to top shape.

  1. Turn off the power. This is the first thing you must do; in the name of safety. You can get injured if you don’t do this, so, take precautions.


  1. Identify the thermocouple. The safety device is a thin metal tubing or a wire, if you will. It should be next to the pilot light tube. Depending on the type of water heater you have, you might need a wrench or screwdrivers to loosen the thermocouple for cleaning.

Emerson TC18 Universal Thermocouple, 18-inch

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  1. Clean the corrosion or buildup. Use emery cloth, steel wool, or abrasive sponge to gently scrub off the buildup. Apply even pressure and be sure to scrub the threading of the screws that connect the thermocouple to the unit. Be careful about the type of cleaning product you use and ensure it is not flammable.


  1. Wipe with a lint-free cloth. After scrubbing, further clean the thermocouple of the water heater with a microfiber cloth to remove excess particles.


  1. Reattach the thermocouple. Once you’re sure the thermocouple is clean, fix it back to the unit.


  1. Turn on the water heater. Relight the pilot light too and wait to see if the water will heat up. If it does, congratulations! The cleaning solved the problem. However, if it doesn’t, then you might have to replace the thermocouple.





How to Replace a Thermocouple

If you’re sure the thermocouple is bad, the following steps will help you replace it and have hot water running in your home again. You must turn off the power before proceeding with this process.

  1. Detach the thermocouple from the whole. Use wrenches or screwdrivers (depending on which you need) to loosen the nuts and screws on both ends that connect the thermocouple to the water heater.


  1. Slide the thermocouple out of position. This will disconnect it on both ends.


  1. Use the old thermocouple to purchase a new one. If you will be buying a replacement thermocouple from the store, take the old one with you to ensure you get a match. If you’re going to buy one online such as this one, make sure you do a good comparison. Alternatively search with the brand name.


  1. Install the new thermocouple. If you purchased the right one, this should be an easy process. Slide the thermocouple into the metal bracket and tighten it in place. First, turn the nuts in place with your hands to avoid stripping them. Then tighten with light pressure using a wrench.


  1. Turn back on the water heater. If everything is done correctly, your water will heat up in a bit.





The following posts will show you how to clean other appliances in your home:




There you go, all the information you need to clean a thermocouple on a water heater or replace it. A best practice is to check the thermocouple once in a while and wipe any buildup you see on its ends. This will keep it working at its best and make it last longer. Thank you for your time.



How to Clean the Thermocouple on a Water Heater — FAQs

How do I know if my thermocouple is bad?

Where there’s a thermocouple, there’s a pilot light. The primary job of the thermocouple is to keep the pilot lit as long as the device it’s working for is in operation. Therefore, if the pilot light won’t stay on, the thermocouple could be the problem. However, in a gas water heater, if the light won’t come up at all, and you’re sure the gas is on, an obstruction in the pilot tube might be the problem. But if the flame lights and goes out when you let go of the gas knob, then the thermocouple is the culprit.


What are some types of thermocouple?

There are many different types of thermocouples and are best suited for different applications. They vary based on properties, stability, melting points, etc. The following are some types of thermocouples:

  • Platinum/Rhodium alloy thermocouples – Types B, R, S
  • Tungsten/Rhenium alloy thermocouples – Types C, D, G
  • Nickel-alloy thermocouples – Types E, J, K, M, N, T
  • Others – Chromel-gold/iron alloy , Type P, Iridium/Rhodium alloy, HTIR-TC, Pure noble-metal, Platinum/Molybdenum alloy thermocouples


Are there universal thermocouple?

Some thermocouples are designed with adapter fittings that make them usable with scre-in, push-in, and clamp type pilots. These thermocouples are often designed for 30 mV systems and gas furnaces. Kindly do not mistake the universality of thermocouples as being usable for any application. There are many types of thermocouples that are best suited for the application they are created for.


What is the difference between a thermocouple and an RTD?

Thermocouples and RTDs (Resistance Temperature Detector) are both used for measuring changes in temperature, only that RTD use the principle of resistance to the flow of electricity. One main difference between a thermocouple and an RTD is that thermocouples are more sensitive and respond faster. The other difference is that RTDs are more precise than thermocouples. While RTD can be accurate up to 0.1 degrees Celsius, a thermocouple is not precise at less than 1 degrees Celsius.


What can make a thermocouple fail?

Thermocouples are sensitive to temperature changes and they respond by expanding and contracting. If this happens too often, over time, the thermocouple will weaken. If the rapid cahnges in temperature continues, the thermocouple will eventually break and fail to serve its purpose. Thermocouples are designed to last a long time, though usually not as long as the device they work for. So, you might not have to replace yours frequently.


What is the difference between the Type J and Type K thermocouple?

The Type J and Type K thermocouples are quite commonly used. Type J is made of Iron and Nickel/Copper alloy which can measure temperatures between 0 to 816 degrees Celsius. They’re accurate at their stated temperatures and are inexpensive. The Type K thermocouple is made with Chromel and Nickel/Aluminum alloy. It is more versatile since it can measure a wider range of heat between 0 and 1260 degrees Celsius, though it is more expensive that the Type J thermocouple.