How do you replace a thermocouple on a gas heater

1 cause of pilot lights that won’t stay lit is a worn-out thermocouple. It’s easy to replace and a new one costs $5 to $10. … Then detach the thermocouple from the burner and take it with you to the home center or hardware store to ensure you buy the right replacement.

Can I replace a thermocouple myself?

How do you replace a thermocouple on a heater?

Detach the old thermocouple as described above. Remove the new thermocouple from the packaging and uncoil it to the appropriate shape. Attach the new thermocouple to the pilot assembly and the gas valve. Turn the furnace back on and test it to see if the pilot stays lit.

How do you know if you have a bad thermocouple?

If you can’t get the flame to light at all, and you’re sure the gas is on, there’s probably an obstruction in the pilot tube. If the flame lights and goes out when you release the gas control knob after holding it in for the recommended 20 to 30 seconds, that’s the sign of a thermocouple malfunction.

How much should a plumber charge to replace a thermocouple?

Thermocouple Replacement Cost Calling a professional plumber to install a new thermocouple should only be up to $150. If you do the work yourself, you will only pay the price of the part which is about $20.

Will a pilot light stay lit with a bad thermocouple?

A thermocouple senses the heat of the pilot and allows gas to flow to the burner. A bad thermocouple will shut off gas to both the pilot and the burner so the pilot light won’t stay lit.

How do I know which thermocouple to buy?

You want to get one that is about the same length as the one you have. They are sold in in 6″ increments for the shorter lengths, 18″, 24″, 30″ and so on. For a water heater, 18″ and 24″ are common, although longer ones are possible. Remove the old thermocouple and measure it to see what length you need.

What causes a thermocouple to go bad?

The presence of oxygen causes a reaction in the thermocouple that can wear down the part and make the wires become thinner and more brittle. Oxidation can be caused by a small amount of oxygen making its way into a sealed environment and reacting with the pure metal of the thermocouple.

Can you clean a thermocouple?

Yes, you can clean a thermocouple, but the task must be done with a light touch. Remove the thermocouple from the process assembly, using a steel wool or emery cloth, lightly clean the tip removing any build up.

How do I remove an old thermocouple?

Open the Access Cover. Remove the furnace’s access cover. …
Remove the Old Thermocouple. Using an open-end wrench, unscrew the nut that holds the thermocouple end fitting into the gas control valve. …
Install the New Thermocouple. …
Connect the Gas. …
Turn On the Gas and Power.

Article first time published on

Are thermal couplers universal?

Thermal couplers are very similar, but the length and fittings used to install them can differ. The universal lead-length gas thermocouple is designed for gas furnaces and 30 millivolt systems. It includes universal connections for adapters and is compatible with pilot screw, push-in or clamp burners.

Is a flame sensor and thermocouple the same thing?

People tend to use the terms “flame sensor” and “thermocouple” interchangeably. In truth, while they basically perform the same job, they’re not the same thing. If your furnace uses an electronic controller, it’s got a flame sensor. Thermocouples are used on standing pilot furnaces that have pilot lights.

How do you clean a dirty thermocouple?

The best way to clean your thermocouple is to use either a piece of steel wool or the coarse side of a sponge to gently clean off any soot or other remnants. You can use a pencil eraser to clean between the threads of the screw that connects the thermocouple to the control valve of your system.

Where is the thermocouple on a gas heater?

Your furnace’s thermocouple is usually located right in the flame of the furnace’s pilot light. Its copper tubing makes it easy to spot. The thermocouple is made up of a tube, a bracket, and wires.

Should thermocouple be in pilot flame?

The pilot flame should touch the thermocouple at a specific level. If the flame is blue and weak, and barely reaches the thermocouple, it needs to be stronger. If it extends well above the thermocouple, it’s too strong. … Install a new thermocouple by screwing it in, heating it up a bit, and then lighting the pilot.

Why won't my pilot light stay lit on my gas furnace?

If your pilot light won’t stay alight, it might be the thermocouple. Sometimes dust buildup collects on the thermocouple and blocks the sensor. Try cleaning the thermocouple and then relighting the pilot light. If it continues to go out, the thermocouple might need to be replaced.

What does it mean when your pilot light keeps going out?

A faulty, misaligned, dirty, or damaged thermocouple is often the culprit behind your pilot light going out. The thermocouple is an automatic safety shutoff device that prevents the gas valve from opening if the pilot light is out.

Can you bypass thermocouple on furnace?

Realistically, you have just disabled the thermocouple, but you can also reach in and unclip it from its holding bracket where it meets the pilot light. In most cases it will be held on with a gravity clip, but some are held on with a screw that must be removed with a small screwdriver.

How much does a thermocouple cost?

It costs $150 to $250 to replace a thermocouple. It checks to make sure the pilot light is on.

How do you maintain a thermocouple?

A temperature indicator or recorder should be checked, either with a potential divider or a standard thermocouple at least once a month, whether it is used much or little. Terminals must be kept clean, insulation must be checked, and thermocouples themselves must be recalibrated.

How do you clean a thermocouple pilot light?

Cut off the gas to your furnace. …
Remove the pilot light and thermocouple assembly. …
Use your pliers or wrench to remove the pilot light and thermocouple from the bracket.
Using the wire brush, brush away the carbon buildup and soot from both components.

What is a thermocouple on a gas heater?

Thermocouples are sensors used to measure temperature. It is a device used inside a gas furnace in Kansas, to assist the pilot light in keeping your furnace running and safe. It works rather like a fail-safe to keep unburned gas from accumulating and burning, exploding or causing another type of health risk.

How do you wire a thermocouple extension?

Thermocouple extension wire is used to carry the signal from the thermocouple sensor to the readout device while maintaining a high degree of accuracy. The extension wire material must match the material used in the positive and negative leg of the thermocouple type (e.g. type K) being used in the application.

What happens when flame sensor goes bad?

What happens when a flame sensor goes bad? … Without a flame sensor, your furnace will keep emitting gas even when there’s nothing to ignite it, resulting in hazardous gas buildup. If your flame sensor is dirty or faulty, it will automatically shut down the heating unit if it doesn’t detect a flame.

How do you trick a flame sensor?

Shut off power and gas to the furnace.
Remove the sensor.
Clean away soot and corrosion with a clean emery cloth.
Reinstall the flame sensor.
Restart the furnace.

Can I use sandpaper to clean a thermocouple?

You can use Emery cloth sandpaper to gently clean any debris or build-up from the end of the thermocouple. If present, you should also clean off any corrosion where the power wire connects to the thermocouple terminal. Be aware, you may need to detach the thermocouple from the burner assembly to clean it thoroughly.

Can you sand a thermocouple?

Water Heater Thermocouple Cleaning in 5 Steps This is always the first step when working on a water heater. … Clean the thermocouple – using the emery cloth sandpaper, sand the ends of the thermocouple and then give it a finishing touch with the lint-free cloth.