troubleshoot furnace pilot light

Furnace Pilot Light Keeps Going Out – Troubleshooting Steps

If the furnace pilot keeps going out, you cannot wait to manage the issue, especially in the middle of winter. Such a problem isn’t something that will solve on its own and it can leave the house in the cold. To stay warm and comfortable, you should manage the problem immediately.

When the furnace pilot light doesn’t stay lit, it can be tricky to find the cause. Several problems can make the furnace not stay lit. Keep reading to find out more and troubleshooting tips.

First thing: where is the pilot light?

If you don’t know where the pilot or thermocouple is, you have to inspect the unit—some furnaces don’t have a standing pilot light. As a matter of fact, standard pilot lights are typical for old furnaces. Many new models come with intermittent pilot lights or hot surface igniters. With such models, the pilot will light (with the hot surface igniters, the igniter surface will heat) when the thermostat commands heat.

Regardless of the pilot configuration, the thermocouple is typically located near the burners; a removable metal rod should be within reach.

Why does the furnace pilot light go out?

Various problems can impede the furnace pilot light from staying lit. Here are the possible issues:

Dirty thermocouple

Many homeowners are tempted to re-light the pilot light when it goes out. However, the attempt could be unsuccessful and the pilot light will keep turning off. You should check out the thermocouple and see if it’s dirty. If it is, you need to shut off the gas, let the furnace cool down, and gently clean the thermocouple. Use some fine-grind sandpaper to clean it.

Once the thermocouple is nice and clean, turn the gas back on and light the pilot again. The pilot light should stay lit if the grime and dirt are causing the problem.

Bent thermocouple

The gas valve will automatically shut off when the flame cannot reach the thermocouple because it’s bent. The problem has an easy fix, though. You only need to shut off the gas, wait for the furnace to cool down, and bend the thermocouple into place.

Dirty pilot opening

When the flame is oriented through a dirty pilot opening, it becomes unstable and wavy. The flame will be yellow and not hot enough to heat the thermocouple. You need to solve the problem right away. Begin with turning off the system and get a thin needle to collect clogs that might block the pilot opening. Once you clear the blockage and turn the system back on, the flame should be blown and cone-shaped.

Broken thermocouple

Let’s say you have tried to clean the thermocouple and the pilot opening, but the pilot light still doesn’t stay on. If so, maybe it’s time to buy a new thermocouple. The thermocouple is still a device with a limited lifespan and requires replacement after some time.

We advise contacting a certified HVAC technician to install the new thermocouple.

Poor location of the furnace

The system may not get enough oxygen if the furnace is located in a small enclosed area. If so, it will run out of combustible air and stop the pilot light from staying lit. Additionally, carbon monoxide might build up within the house. If you suspect this is the cause for the pilot light not remaining lit, you should contact the professionals. They will relocate the furnace to a much more appropriate space. Call them immediately, as carbon monoxide can be lethal.

The flame is weak

One of the most apparent reasons why the pilot light doesn’t stay lit is a problem with the furnace. Simply lighting the pilot light and checking out the flame will give you the necessary information.

A weak and yellowish flame means the furnace doesn’t get hot enough to ignite the flame. An intense flame should be bluish-green with a bit of yellow on top. A weak flame doesn’t stay lit for a long time. You need to call the professionals to investigate the furnace further.

Fluctuating natural gas availability based on demand

Sometimes, there’s nothing wrong with your furnace, but it’s simply a problem with gas availability. When natural gas consumption peaks, the “gas grid” in your area could be close to its capacity and reduce the gas pressure from time to time. Even the slightest fluctuation in the gas supply to the furnace is enough for the pilot not to stay lit.

If you suspect such a situation, ask your neighbors if they also encounter problems with natural gas. If the problem doesn’t disappear, you should contact your utility company to look into it.

There’s a strong draft

When the pilot light re-lights effortlessly after going out overnight, a draft may have blown it in the first place. It can happen when the wind is strong. Also, a leak in the output duct of the furnace can cause air to blow into the area. We recommend you open and clear every intake air register in your house to eliminate the “vacuum” effect in the inlet.

A bad gas regulator

The gas regulator should be at the house’s gas meter. Its role is to reduce the natural gas pressure before it enters your house and gas appliances such as the furnace. When the regulator is old or damaged, it won’t let the gas run firmly or steadily enough to light the furnace’s pilot light.

Should other gas appliances also develop pilot problems, the gas regulator is defective and causes the pilot light not to stay lit.

We recommend hiring professionals to examine if the gas regulator has issues. If it’s faulty, they will replace it.

Bad gas valve

The furnace’s gas valve sends gas to the pilot light and combustion chamber. Without the gas, the pilot light cannot light. When the valve is accidentally turned to the OFF position or damaged, the pilot light will keep turning off.

Once it’s gone bad, the gas valve cannot be repaired, so you need to contact the HVAC technicians to replace it.

How to fix a pilot light that keeps going out?

Contacting a reliable HVAC company is the safest and most effective method to manage a pilot light that doesn’t stay lit. Sometimes, the causes have easy fixes that any homeowner can perform. If the reason is a draft nearby that blows out the light, simply closing the window will fix the problem.

Sometimes, all you need to do is to wait and see if the problem solves on its own or worsens. A temporary problem with the gas supply is not a reason to stress and call the certified HVAC technicians.

The steps to take to re-light the gas furnace pilot light

Check out the exterior of your furnace and see if there are particular directions printed. It’s common for furnaces to come with step-by-step directions printed on the outside of the tank to help you light the pilot light.

Please make sure to cross-check the instructions down below with the ones printed on your equipment. Always do according to your equipment instructions.

Step 1

Find the gas valve with printed on /off and pilot settings. You should find it within the pilot light assembly.

Step 2

Turn the valve to the OFF position and wait for 3 minutes so that furnace cools down.

Step 3

Turn the valve to the pilot setting and keep a lighted match close to the opening of the pilot light. Don’t put the match inside the opening and hold the lit match 1-3 inches away from the opening.

Step 4

As you hold the lit match, identify and push the reset button on the pilot control panel. See that you press and keep the button pressed until the pilot light lights up. You must set the valve to ON when the light is back.

Step 5

When the pilot light doesn’t stay on, you need to go back and see what might be the reason. Use a wire or a coat hangar to remove dirt or debris built around the pilot light opening.

Should the pilot light doesn’t stay lit after several attempts, it’s time to call the professionals. Sometimes, they’re the only ones able to save the day.


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