Sometimes, furnace problems are minor and can be fixed quickly. However, they can develop into bigger issues that require repair or even replacement if not tended to. Without your furnace, your home’s temperature would become uncomfortable – especially in the winter months. To avoid this, be on the lookout for these signs your furnace is going out.

Seven Signs Your Furnace Is Going Out

1. Your Furnace Is Over 15 Years Old

Furnaces don’t last forever. If your furnace is 15 years old or older, it’s best to replace it as soon as possible. Even if it’s working correctly now, it could break down anytime. Imagine having your furnace fail in the middle of the night during a cold snap. You can avoid that by upgrading to a new furnace.

2. Your Heating Bills Are Higher Than Average

Are you spending more on energy or gas, whether you have an electric or gas furnace? If your answer is yes, then your furnace might be the culprit.

Your furnace might be having to work too hard to heat your home, resulting in a spike in utility bills. This could be due to a number of issues, from dirty filters and a lack of maintenance to outdated technology. As previously mentioned, furnaces have a lifespan of up to 15 years. If your furnace is older, then it might be time to upgrade to a newer, more energy-efficient model.

3. Your Furnace Is Making Odd Noises

Loud, unusual noises coming from your furnace is one of the telltale signs that it’s on its last legs. In addition, the type of noise your furnace makes gives further clues as to what exactly is wrong. For instance, rattling and rumbling noises indicate a loose component, whereas banging sounds point toward an issue with the combustion chamber, while high-pitched squealing noises might mean a damaged belt. A professional will determine the cause of the noise and, if possible, fix it. Otherwise, you might need to get your furnace replaced.

 4. Uneven Heating Throughout the Home

Are some rooms in your home chilly, while others feel like summer in the tropics? This is likely because your furnace can no longer distribute heat evenly throughout your home.

Uneven heating is a common sign that a furnace is going out. As your furnace ages, it gradually loses its ability to keep your indoor spaces at an even, comfortable temperature. Contact a trusted technician to learn if your furnace needs to be replaced or whether less serious factors are causing the issue.

5. The Pilot Light Is Yellow

If you have a natural gas-powered furnace, check the pilot light. A furnace that’s working as it should be has a pilot light with a blue flame. Meanwhile, a yellow flame indicates problems with the furnace, such as a backed-up or dirty burner.

This means your furnace isn’t heating as well as it should. Worse, the carbon monoxide (CO) it’s producing might not be vented correctly. A yellow flame is one of the signs a furnace is going out that should not be ignored, as a CO leak is potentially dangerous to the inhabitants of the home. 

6. Your Furnace Cycles On and Off

Does your furnace suddenly shut off and then turn back on? This could be due to dirty air filters, blocked air vents, a dying fan motor or a problem with the heat sensor. Unfortunately, it could be because of other, more complicated problems, like a malfunctioning fan limit switch. This is the part of the furnace that controls when the blower fan turns off and on. A defective switch can cause a furnace to stop functioning altogether.

A technician can tell you if your furnace is short-cycling due to any of the reasons mentioned above and if it can be repaired. They’ll advise you on the best furnace models for your home and lifestyle if replacement is warranted.

7. Rust on Flue Lines

Another one of the signs that a furnace is going out is the fact that there is rust on the flue lines. This indicates that CO is being incorrectly vented, which is a major repair or replacement emergency. 

If the flue lines are rusted, then they might not be venting all of the CO your furnace is producing outdoors but rather releasing some of it back into your home. Exposure to carbon monoxide for prolonged periods could lead to a host of flu-like symptoms and, if undetected and untreated, could be fatal.

For this reason, if you see any rust on your flue lines, don’t hesitate to call a trusted technician right away. Apart from fixing the rusting, they’ll get down to the bottom of the problem and figure out what’s causing the rusting and whether it can be repaired or if the entire furnace needs to be replaced.

Have Your Furnace Serviced by the Experts

The furnace is an important part of any home, responsible for evenly heating rooms and ensuring indoor temperatures are comfortable and warm even in the coldest weather. However, it is a complicated machine, and infrequent servicing, age and other factors can affect how well it functions.

If you’ve spotted any of these signs a furnace is going out, reach out to Raven Mechanical, a trusted full-service mechanical construction company. We offer repair and installation of heating and cooling equipment to residential and commercial clients. Contact us at to learn more about our services.

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