If you’re a home owner, you’ve likely found yourself thinking, “why does my furnace make a loud noise?” on many occasions. There are many different types of furnace noises you might encounter, from clicking and popping noises to humming and buzzing sounds. Certain sounds only happen when your furnace starts up, while others occur during regular use. Though some of these sounds are part of your furnace’s normal operation, they can be indicators of both minor and major problems.
The exact cause of these strange – and often annoying – noises can vary depending on the model, condition, and age of your furnace. However, by listening carefully to the sounds made by your HVAC equipment, you can discover clues as to where the noises are coming from and what might be creating them.
In this article, we’ll explore a number of the most common furnace noises you might be experiencing and their potential causes.
Furnace Makes Loud Noise When Igniting
If your gas furnace is making a loud noise when starting (such as a “boom” or “bang” sound), there are typically two main culprits.
The first is a fairly minor problem, which is caused when your furnace starts up the metal ductwork in your HVAC system expands as air begins to move through it. This is the same reason that you might experience your furnace making a knocking noise. We recommend replacing your air filter, opening heat registers around your home and having your ducts cleaned to minimize the noise. If this does not resolve the noise issue when turning on your furnace, it is best to call in a professional to find a solution.
The second cause of loud noises when your furnace ignites is delayed gas ignition. This is a much more serious issue. In this scenario, gas has time to build up in the furnace before it is ignited, causing a much larger “boom” than expected when the gas is ignited immediately. This can result in damage to your furnace’s heat exchanger, which can be very costly to repair. Entrust the troubleshooting of this issue to a pro for your personal safety.
Furnace Fan Noise
One of the top sounds experienced by home owners is the furnace blower fan making noise. When your furnace fan is making noise, it may be dirty or dusty and in need of a good cleaning. While this is an easy way to start diagnosing your furnace fan noise, there are several other causes of fan sounds. A loose drive belt could be causing the fan to operate improperly and make excessive noise as it spins unevenly. If you feel comfortable, you can replace the belt with a new one as indicated in your furnace manual.
Should you notice a furnace exhaust fan noise, it is important to address the problem as soon as possible. This furnace component draws toxic exhaust fumes created by the fuel source (natural gas or oil) out of your home, so it is critical that it functions correctly. While you can examine the exhaust fan for dirt and debris or a loose fan belt, we recommend that a professional diagnose your furnace exhaust fan noise and repair it immediately.
Furnace Clicking Noise
A furnace making a clicking noise while operating normally can indicate a couple of different problems. First, the motor bearings or other smaller-sized parts within your furnace could be moving during operation. Second, the furnace’s inducer fan may make a clicking sound as it operates, especially if it is loose or clogged with dust or debris. Regular furnace maintenance can help prevent these types of issues and reduce annoying clicking sounds.
If a furnace makes a clicking noise when starting, you may be dealing with a more serious ignition system malfunction. Your pilot light may not be working properly and can fail to ignite altogether, making clicking sounds as it attempts to spark a flame.
This furnace popping noise can also be the result of a clogged ignitor or clogged gas valve, both of which can indicate major problems. Your furnace’s flame sensor could also be sensing a problem in your system, shutting off the gas at startup for safety reasons. We highly recommend that you allow a professional to troubleshoot these issues, which can be very dangerous for DIY-ers to handle on their own.
Furnace Blower Motor Noise
Furnace blower motor rattling noises can become annoying fast. When your furnace blower is making noise like humming, screeching, or thumping, it can be a sign of wear or damage. You may be dealing with a bad belt, a problem with the motor bearings or even a broken part. No matter what type of noise you hear, it is best to shut your furnace down right away so you can look for the cause.
Furnace blower noise reduction is one of the top concerns of our customers. Sometimes, there is nothing really wrong with your blower motor, it is just too loud for your liking! In this case, a furnace repair expert can examine the blower motor and find a solution for reducing the noise without compromising the efficiency of your equipment.
Furnace Humming Noise
Is your furnace making a loud noise while running? Humming sounds are one of the primary concerns of home owners dealing with a noisily running furnace. When your furnace is making a humming noise, there are several components that may be the source:
- A Worn or Failing Motor – Motor failure is the likely cause if you notice a humming sound appear suddenly. This is a sign that your furnace is about to stop working, so call a furnace repair technician as soon as possible.
- Loose Ductwork – As air passes through your HVAC system, it can vibrate the ducts and cause a humming sound. Try securing the joints between ducts with extra sheet metal screws and duct tape, or use additional straps to secure ductwork to your joists.
- Electrical Transformer – As electrical current moves through your furnace’s transformer, it can make a humming noise that can be loud, but not dangerous. If you wish, you can try tightening the bolts that secure it to attempt to reduce the humming sound.
- Loose Parts – Over time, components can become loose from vibrations, resulting in your furnace making a loud humming noise. Check that all screws are secure and bolts are tightened.
Furnace Buzzing Noise
A furnace vibration noise is often caused by an unbalanced blower motor. If your furnace is making a loud buzzing noise, it may be the result of an off-kilter blower. Check the blower motor and fan for obstructions or excessive dust and clear them away. A buzzing sound can also indicate a failing blower motor, so be sure to have an HVAC technician take a look at it if you are concerned.
A furnace buzzing noise when running could also be caused by loose access panels or components of your furnace’s housing. While the furnace is running, these loose parts can vibrate excessively, creating an annoying buzzing sound. This issue can be resolved by tightening all screws that secure the access doors to the exterior of the furnace.
As mentioned above, you may hear a buzzing-type sound coming from the transformer box located near your furnace. This is completely normal, but you can check to see that it is securely mounted to reduce the buzzing noise and prevent future damage to the transformer box.
Furnace Making High-Pitched Noise
Hearing a high-pitched noise when your furnace is running? Start by looking at the blower speed. Many modern furnace models allow you to adjust the speed of the blower fan, which may eliminate the sound you’re experiencing. Contact an HVAC specialist to adjust this setting for you.
You could also be hearing a high-pitched whistling sound from your air vents. This is caused by low return air flow, meaning that your furnace’s blower is struggling to pull in air. To resolve this problem, you can replace or clean your dirty air filter, check for blocked or dusty air return vents throughout your home, and open any supply vents that are closed. You may also need your ductwork cleaned and checked for any large debris by a professional duct cleaning company.
Furnace Draft Inducer Blower Noise
Furnace draft inducer blowers push air and gases out of your furnace and towards outside, improving the quality of the air that moves through your furnace. A furnace inducer motor noise can be one of the main problems home owners experience with this component, which is mostly found in newer, high-efficiency furnaces.
If you hear noises coming from your draft inducer blower, it likely needs total replacement. This part is unfortunately difficult to rebuild, so your best option is to have a new unit ordered and replaced by a professional.
Furnace Making Grinding Noise
A furnace making a grinding noise is definite cause for concern. Loud grinding or scraping sounds can indicate that metal is rubbing against metal somewhere within your furnace. The most common cause of this noise is a problem with the fan or blower wheel rubbing against other interior parts. A part is most likely broken or loose and must be replaced. Another cause of a grinding sound could be worn bearings, which require inspection and lubrication. Keep in mind that not all of today’s furnace motors require oiling, so check your manual.
If you hear a grinding sound, shut off your furnace immediately to prevent any further damage. Next, call an HVAC repair company for help in diagnosing and repairing the damaged components.
How to Reduce Furnace Noise
If you’re left wondering how to reduce furnace noise for good, it’s time to call in a professional. Furnace noise reduction can be achieved through any number of repairs or adjustments, but an expert must first correctly diagnose the problem.
Didn’t see an explanation for your mysterious furnace noise above? Our trained technicians are highly skilled in determining the source of your furnace noises and repairing or replacing necessary components to get your furnace running quietly again. If you’re tired of your noisy furnace, give Evam Canada a call today at 1-905-624-5544, or contact us online to schedule a repair appointment.