Almost all mechanical devices make some noise as they operate. The same principle applies to the HVAC system in your Portland, Oregon home. While a little bit of noise is expected, if your furnace makes loud and unusual sounds, this typically indicates a problem that could require repair. Here are some of the most common furnace noises our customers hear and the likely culprits behind them.

A Scratching or Scraping Noise

If you hear a scraping or scratching noise emanating from the HVAC system, there is likely something wrong with the blower wheel. Since this noise sounds like metal scratching against metal, it will likely catch your attention and make you want to take immediate action.

There are several reasons why your blower wheel makes a scraping sound. For example, it might be broken and needs to be replaced. Or it could have worked its way loose, and now it is hitting against the blower casing.

Because of the potential damage that a malfunctioning blower wheel can cause, it is best for you to immediately turn off your HVAC system, call our technicians, and let us help you make that annoying noise disappear.

Screeching or Squealing Noises

In this case, the likely culprit is your blower motor. In order to facilitate the rotary motion of the motor, there are bearings. These bearings require a lubricant to work correctly. With time, and if it is not adequately maintained, the blower bearings can become dry, causing that screeching noise. If the problem is caught early enough, an HVAC technician may be able to address the noise by using a synthetic or mineral lubricant.

The second reason for a screeching sound could be a broken belt. It is similar to the screeching sound you hear in an automobile if a belt is damaged or loose.

A Whistling Noise

When your HVAC system makes a whistling noise, the blower motor is likely to be the culprit. As a blower motor starts to malfunction, some airflow issues could develop. When the airflow is too low, the blower must work hard to pull in enough air to be heated. This leads to that whistling sound.

A dirty furnace is usually at fault for a low airflow issue with a furnace. Getting the filter replaced or cleaned may solve the problem. If not, a technician can do further troubleshooting to identify the source of the sound.

Banging or Popping Noises

These sounds are not necessarily abnormal. Your furnace will make these noises as the ducts expand and contract in reaction to the heated air flowing through them. However, if your furnace sounds like fireworks, it could signal that you are facing a more significant issue.

Another issue could be a dirty burner, leading to delayed ignition. Or it could be a cracked heat exchanger that causes a loud sound. Excessive banging and popping sounds should not be ignored. If there’s a problem with the heat exchangers or a problem with the ignition, these could compromise your HVAC system, affect the safety of your home, and lead to some costly repairs.

Rattling Sounds

If your furnace is rattling, there is likely a loose door or panel. Usually, these issues can be resolved by tightening a few loose screws.

If a loose panel or door is not the issue, there could be loose parts inside the furnace that are rattling. Your furnace is made up of a lot of intricate moving parts. If they were improperly installed or were not tightened properly, they may become loose over time. It is best to turn off your furnace if you hear that rattling sound and have our professional technicians come and tighten them.

A rattling sound could come from a damaged heat exchanger in extreme cases. When your heat exchanger is cracked or damaged, it could lead to carbon monoxide in your home. This dangerous, odorless, colorless gas could lead to carbon monoxide poisoning.

Rumbling Sounds

It is normal for your furnace to make a slight roaring or rumbling sound, especially when it gets to the end of its heating cycle. But if you hear a loud rumble, especially after the furnace has been running for a little bit during the day, this could point to an issue with the burner.

When the burner is damaged, the furnace will produce a rumbling sound because fuel continues to burn in the combustion chamber even though the burners are off. This is not an issue that you want to leave unresolved. A technician should evaluate and repair it to prevent further damage to the unit and the possibility of carbon monoxide poisoning.

Buzzing or Humming

A low humming sound emanating from your furnace is normal. However, if your furnace is making a loud buzzing noise, it could be an issue with the blower motor. There could be a problem with the fan as well. You will need a technician to inspect the electrical components of your furnace and identify the reason for the sound.

Clicking Sounds

You might hear an initial clicking sound when you turn your furnace on. This is normal. However, if you continue to hear clicking sounds as the furnace goes through its heating cycle, there’s an issue with your furnace. Repeated clicking sounds could indicate a problem with the ignition system. If your furnace has issues igniting, the clicking sound could mean the igniter is struggling to activate. Ignition problems are usually the result of a defective engine border valve, dirty burners, or a damaged flame system.

Your control panel could also cause issues that result in clicking sounds. In some models of furnaces, a faulty fan motor might start to click if it is about to fail. Your best bet is to have a professional technician inspect your furnace and find the source of the sounds.

Thwapping Sound

You would hear a thwapping sound if a playing card got stuck in the spoke of a bicycle tire. This sound usually happens when something affects the blower’s blades as it spins.

The sound could indicate an issue with the motor belt or that something is causing it to wear out quickly. Excessive wear and tear on the motor belt can force the motor to work harder, reducing your furnace’s efficiency.

HVAC Professionals That Never Lose Sight of Their Responsibility

At Apollo Plumbing, Heating & Air Conditioning, we are proud to be HVAC professionals that never lose sight of our responsibility to you as our customer. Every team member is here to help you make your home a comfortable place to live. We offer 24/7 emergency repair and are proud to have an A+ rating with the Better Business Bureau.

Our services include indoor air quality testing and solutions as well as HVAC installation, maintenance, and repair. We install heat pumps, ductless mini splits, and traditional HVAC systems. Our plumbing services include leak detection, water heater installation, sewer backup repair, mainline repair, and unclogging clogged pipes. Contact Apollo Plumbing, Heating & Air Conditioning today and see for yourself what it’s like to work with HVAC professionals who take pride in what they do. Our offices are located in Troutdale, OR, Vancouver, WA, and Eagle, ID.

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Brandon Bird
Brandon Bird

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