If your furnace pilot light keeps going out, it’s likely you have a broken thermocouple in your gas furnace. The thermocouple is a rod that comes into physical contact with the flame in your system. … When this component is not able to detect the flame, it will close the gas valve to prevent a gas leak in your home.

How do I know if my thermocouple is bad on my furnace?

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.

Why is my pilot light not staying lit on my furnace?

Some common causes include issues with the thermocouple and pilot tube. The thermocouple detects the pilot light via sensors. … A dirty pilot tube can also prevent the pilot from staying lit. If the pilot tube is dirty, let the furnace cool down and turn off the gas.

How do you fix a pilot light on a furnace?

1. Find the pilot light assembly and its reset switch. The furnace’s pilot light is usually positioned at the bottom of the unit by a knob. …
2. Set the reset switch to off. Turn the knob to the “Off” setting. …
3. Wait a moment. …
4. Relight the pilot light. …
5. Observe the furnace.

Can a thermocouple be cleaned?

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.

Does gas turn off when pilot goes out?

This is because all modern gas appliances with pilot lights have a fail-safe device that closes off the gas to the appliance in the case when the pilot may go out. … If the pilot light goes out for any reason, the current stops, the valve closes, thus preventing any gas from leaking.

How much is a thermocouple?

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. Rather than trying to unfasten the thermocouple inside the water heater’s burning chamber, it’s easier to remove the whole burner and thermocouple assembly.

Is the pilot light supposed to stay on in a gas furnace?

Leaving the gas on keeps this compound moving out of the tubes. Keeping the pilot light on will also keep moisture out of the unit and in turn, help prevent corrosion. … As you can see, it’s probably best in most cases to extinguish the pilot light in your gas fireplace during the months when you don’t need heat.

How much does it cost to relight a pilot light?

Most service providers will charge a standard fee per visit that typically covers the cost to relight a gas water heater. This service call price can range from $80 to $100.

How much does it cost to replace a thermocouple?

It costs $150 to $250 to replace a thermocouple. It checks to make sure the pilot light is on. It will shut the gas off if it’s not.

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How often do thermocouples need to be replaced?

How to Tell if You Have a Bad Thermocouple? Thermocouples can last up to 10 years if properly installed and maintained, while furnaces can last 15-20 years, although either may wear out sooner in multifamily units.

Do all furnaces have thermocouples?

Most gas furnaces use either a flame sensor or a thermocouple, sometimes referred to as a “thermal coupler.” Both are safety devices that sense the presence of a flame and control the flow of gas to the appliance accordingly.

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.

What causes thermocouple failure?

Changes in temperature can cause regular expansion and contraction in metal, which will cause thermocouples to weaken over time. After enough time, metal fatigue can cause a thermocouple to break. … If thermocouples start to give out unusual readings, it may be suffering from metal fatigue.

When should pilot light be turned off?

A little heat is produced when your pilot light is on so turning it off in summer can help reduce the heat inside your home. The less heat there is, the less you have to use your air conditioner needs to cool down the house. You can get savings and conserve energy if you turn off your pilot light.

Can you get carbon monoxide poisoning from a pilot light?

A yellow or orange pilot light will produce carbon monoxide – an odourless, colourless gas that can fill your home and cause carbon monoxide poisoning. Symptoms of this condition include dizziness, headache, fatigue, nausea, unconsciousness, brain damage and death.

How do you tell if your gas has been turned off?

When the long side of the nub or handle is parallel to the incoming gas line, it’s open and the gas is flowing. When it’s turned a quarter turn, perpendicular to the incoming pipe, it’s closed.

Who should I call to light a pilot light?

Instead, leave the house and call your local gas company or 911.

Why do pilot lights go out on hot water heaters?

Some of the most common reasons that water heater pilot lights go out include: A faulty thermocouple. … Over time, thermocouples can begin to malfunction and shut off the gas supply to the pilot light even if it’s burning properly. A bent or dirty thermocouple.

How much does a furnace pilot light cost?

Running a pilot light for 1 hour costs about 1 cent (0.62 cent/hour for natural gas and 1.64 cent/hour for propane). Monthly costs of running a pilot light range from $4.49/month (natural gas) to $11.34/month (propane).

Should a pilot light always be on?

Generally speaking, it is safe to leave your continuous pilot light on at all times, assuming it stays lit (more on this in a moment). While it does cost more to keep your pilot light on in between uses, it can actually have some benefits to your system.

What do thermocouples do?

A thermocouple is a sensor that measures temperature. It consists of two different types of metals, joined together at one end. When the junction of the two metals is heated or cooled, a voltage is created that can be correlated back to the temperature.

Where is a thermocouple in a furnace?

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?

If the pilot light goes out, the thermocouple detects it and shuts the valve supplying gas to the pilot. The pilot flame should touch the thermocouple at a specific level. … If the flame covers the top of the thermocouple and burns steadily with a yellow tip, that’s just about right.

What does a thermocouple do in a furnace?

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 fix a pilot tube obstruction?

1. Remove the cover plate at the bottom of the water heater. …
2. Turn the gas control to the “Off” position. …
3. Locate the pilot tube. …
4. Clean the pilot hole by brushing it with a stiff wire brush. …
5. Screw the bracket back onto the valve and turn on the gas.

How do you unclog a pilot light?

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. For hard to reach areas and stubborn buildup, use the metal file. Wipe away dust with a soft cloth or burst of compressed air.

Why is my pilot light yellow?

The most common reason why a pilot light would start to burn yellow is that the air intake valve to the pilot light is clogged with dirt. … If there is a small amount of dirt blocking the air, the yellow color might only be at the tip of the flame. If there is a large amount of dirt, the entire flame will burn yellow.

How can you tell if a thermocouple is bad?

Place one test lead on the side of the thermocouple and the other to the end that screws into the gas valve. If the thermocouple has proper continuity, a small resistance reading should be visible on the multimeter. Many multimeters also indicate continuity with an audio alert.

How do you jump a thermocouple?

1. Move the tilts switch wire aside.
2. Remove your thermocouple from the heater using an 8mm wrench.
3. Pull the valve housing aside using your 13mm socket wrench. …
4. Remove the valve using your pliers. …
5. Put your thermocouple back into position.

Can a thermocouple work intermittently?

In electrical circuits, the most unreliable points are electrical connections. So, if in a thermocouple circuit any of the connections suffer from corrosion or lack of intimate metal-to-metal contact, intermittent operation will result.