Furnace Pilot Light Keeps Going Out

You wake up and your house feels freezing cold. You walk down to the dark basement to check your heating machine. You look inside the small metal window on the front door. You notice that the tiny blue fire is completely gone. A furnace pilot light keeps going out when the machine has a dirty sensor or a broken gas valve. This tiny flame is very important for your home. Your heavy machine cannot make warm air without it. We will teach you why this little fire dies and how to fix it safely.

Understanding The Tiny Flame

What A Pilot Light Does

Starting The Main Fire

Your basement heater uses a massive gas fire to warm your house. This big fire needs a safe way to start burning. The pilot light is a very small fire that burns all day and all night. When your wall thermostat asks for heat, the main gas valve opens. The big rush of gas touches the tiny pilot flame. This makes the big fire start safely without exploding.

A Constant Burning Flame

Older heating machines use this constant tiny fire. It never turns off during the winter months. It sits there waiting to do its job. Modern machines do not use a constant flame anymore. They use a small electronic spark to start the fire instead. Read our Furnace Wont Ignite Causes And Quick Fixes guide to learn about electronic sparks.

The Safety Sensor

What Is A Thermocouple

There is a thin copper wire sitting right next to the tiny blue flame. This wire is called a thermocouple. It acts like a digital thermometer for the machine. The little fire constantly heats up this copper wire. The hot wire sends a small electrical signal to the main gas valve. This signal tells the valve that the fire is burning safely.

Stopping Dangerous Gas

The copper wire cools down immediately if the tiny fire goes out. The electrical signal stops traveling to the gas valve. The gas valve shuts completely to stop all fuel from flowing. This prevents your dark basement from filling up with explosive gas. The sensor protects your home from a terrible disaster.

Common Reasons It Goes Out

The Dirty Thermocouple

A Thick Blanket Of Soot

The tiny fire creates a lot of black soot over many months. This dirty soot covers the copper wire completely. The soot acts like a thick winter blanket. It stops the heat of the fire from reaching the actual copper metal. The sensor thinks the fire went out because it cannot feel the heat. It shuts the gas off and kills the real flame.

Cleaning The Copper Wire

You can fix a dirty sensor very easily. You must wait for the metal parts to cool down first. You can use a piece of light sandpaper to rub the black dirt off the copper wire. You just want to see the shiny copper color again. Read the Energy.gov Heating Systems page to learn how clean parts save you money.

A Bad Gas Valve

The Main Fuel Supply

The tiny fire needs a steady supply of gas to stay alive. A small metal tube carries the fuel to the flame. Sometimes this tiny tube gets clogged with dirt or rust. The fuel cannot reach the fire easily. The flame gets very weak and lazy. A weak flame will easily blow out on a cold night.

When The Valve Breaks

The main gas valve can also break from old age. The internal springs and magnets wear out after ten years. A broken valve will shut the gas off for no reason. Your machine will completely shut down. Check our Furnace Starts Then Stops page to learn about bad gas valves. A professional worker must replace this dangerous metal part.

Air Drafts In The Basement

Wind Blowing The Flame

A tiny fire is very easy to blow out. A strong wind can sneak into your dark basement. The wind pushes the blue flame away from the copper sensor. The sensor cools down and shuts the gas off. The tiny fire dies instantly.

Finding Hidden Drafts

You must find where the wind is coming from. Check the glass windows in your basement. A broken window seal lets cold winter wind blow inside. A loose metal vent pipe can also drop cold air onto the machine. You must seal these holes to protect your tiny flame.

How To Relight The Flame Safely

Following The Rules

Reading The Sticker

You must be very careful when you relight a gas fire. Look at the front metal door of your heavy machine. You will see a large safety sticker with exact rules. You must read every single word on this sticker. The factory gives you the safest way to start your specific machine.

The Five Minute Wait

You might smell a little bit of gas near the machine. You must never strike a match if you smell heavy gas. Turn the main gas knob to the off position. Wait at least five full minutes. This lets the dangerous gas float away safely. Check the EPA Indoor Air Quality site to learn about safe breathing air.

The Lighting Steps

Turning The Knob

Find the main gas knob on the control valve. You will see three words on it. The words are on, off, and pilot. Turn the plastic knob until it points to the word pilot. This setting only lets a tiny bit of gas flow out. It keeps the main big fire from turning on while you work.

Holding The Button

You must push the pilot knob down with your finger. Keep holding it down. Bring a long match or a lighter near the pilot hole. The tiny blue fire should start burning. You must keep holding the knob down for one full minute. This gives the blue fire time to heat up the copper wire. Let the knob go. The fire should stay on. Turn the knob to the on position to heat your house.

When To Call A Professional

Broken Safety Parts

Replacing The Thermocouple

Sometimes cleaning the copper wire does not work. The metal sensor simply breaks from old age. You must buy a brand new copper wire from the store. A professional worker knows exactly how to bend the new wire into the right spot. They make sure the blue flame hits it perfectly.

Fixing The Gas Line

You must never try to fix a broken gas valve by yourself. Natural gas is extremely dangerous and explosive. A small mistake can destroy your entire house. A licensed plumber uses special digital tools to check for invisible leaks. They seal the steel pipes perfectly. Expect to pay about $150 for a professional to test your parts.

Is your house totally freezing right now? Does your tiny fire refuse to stay lit? Our expert heating team can find the broken parts today. We carry brand new copper sensors in our trucks. We will fix your dangerous gas lines safely. We will make sure your family stays warm tonight.

Average Repair Costs

System Component	Main Purpose	Expected Lifespan	Estimated Part Cost	Estimated Labor Cost
Copper Thermocouple	Feels the flame heat	Five to ten years	$15 to $30	$100 to $150
Gas Control Valve	Feeds fuel to the fire	Ten to fifteen years	$150 to $300	$200 to $400
Pilot Tubing	Carries gas to the flame	Fifteen to twenty years	$10 to $20	$100 to $150
Professional Cleaning	Removes thick soot	One to two years	$10 to $20	$100 to $150
Complete Tune Up	Checks total safety	One single year	$20 to $40	$150 to $200

Frequently Asked Questions

Why does my furnace pilot light keep going out after I light it?

Your tiny flame likely dies immediately because the copper safety sensor is covered in thick black soot and cannot feel the heat of the fire anymore.

Can a strong basement draft blow out my small pilot flame?

Yes, a broken window or a loose metal pipe can let strong winter winds into your basement which easily blows out the small unprotected gas fire.

How long should I hold the gas knob down when I light the fire?

You must hold the plastic pilot knob down for at least one full minute to give the new flame enough time to heat the copper safety sensor completely.

How much does it cost to replace a broken copper thermocouple?

A professional heating worker will usually charge you between $100 and $150 to safely install a brand new copper sensor inside your dark metal machine.

Is it dangerous if my tiny gas flame keeps dying every single night?

It is not usually dangerous because the safety sensor shuts the gas off instantly, but it means a part is failing and your house will get very cold.

Conclusion

A cold house means your basement heater has stopped working. You must look inside to see if the small blue fire is gone. A dirty copper wire is usually the main problem. You can clean the wire gently with sandpaper. Follow the safety sticker rules when you light the fire again. A professional worker can replace broken gas parts for about $150. Use our HVAC Services page to get safe heating help fast.