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furnace making noises

Why Is My Furnace Making Noises? This Is Everything to Know

Published on Apr 9, 2020 by Blog in Blog

Did you know that Texas has become the hottest state in the entire country? In fact, of the 50 hottest cities in the nation, more than a dozen are in the Lone Star State! And yes, Dallas has made it to this list.

While Texas may be more known for its insufferable heat, it does get below zero temperatures too. There was even a time when Dallas received almost eight inches of snow!

That said, you should treat your furnace with the same care that you give your air conditioner. If you have a furnace making noises you haven’t heard before, take that as a sign that you have a faulty heater. It’s best to get it checked by a pro ASAP, otherwise, you might get snowed in without any heating.

The question now is, which furnace “sounds” are normal and which ones aren’t? What do these weird sounds even mean?

We’ll take a closer look at some of these odd noises that furnaces make, so be sure to keep reading!

Expanding and Contracting Metal

Sometimes, a furnace that hasn’t been in use for a long time can make a super loud noise right after you power it on. This is usually caused by expanding and contracting metal. Metals, after all, expand when heated and contract when cooled.

In most cases, this is normal. The sound should mellow down the more you use your furnace.

If, however, the heater sound remains super loud or even worsen, there may be a blockage somewhere in the unit. It’s best that you contact a furnace repair technician to have it inspected and assessed.

Uninsulated Ducts or Worn Duct Insulation

It’s also possible for your ductwork system to make a loud, almost-like-gunshot sound. This noise is also usually due to expanding and contracting metal. However, the sound could be worse in air ducts without any insulation or have worn insulation.

In this case, you should consider getting your ductwork updated with better insulation. Not only will this help reduce the noises induced by contracting and expanding metal. It can also help seal those air duct cracks and holes, which could be wasting up to 30% of your conditioned air.

Delayed Ignition Due to Dirty Burners

Dirt and debris can interfere with your heater’s ability to “fire up”. The filth that’s clogging the burners can cause incomplete combustion. This is a safety hazard, as it can generate carbon monoxide (CO) among other harmful gases.

CO alone is deadly, as it’s a silent killer that causes at least 430 accidental deaths in the US every year. CO poisoning also lands up to 50,000 people in emergency departments each year.

Either way, if the heater noise you hear is almost like an “explosion”, turn off the system right away. A furnace’s delayed ignition may be due to a gas build-up, which in turn, can create that very loud sound. You need to have the unit’s burner checked for dirt build-up or damage.

Lack of Lubrication

Screeching, squealing, and wailing noises can all indicate a lack of lubrication. This, in turn, is usually caused by neglect or a lack of proper furnace maintenance and tune-up.

Keep in mind that your furnace has a lot of moving parts, all of which need to remain lubricated. Otherwise, they will get exposed to too much friction, which can wear them down early.

Worse, the excess friction can add up to the heat within the blower motor. This can make the furnace’s internal components even more susceptible to overheating. It won’t take long before your motor overheats and breaks down completely.

Loose Parts

If you hear a loud buzzing, humming, or whirring sound, it may be due to loose parts, such as fasteners. For example, loose bolts and screws have “extra” space between them and the part they’re fastened to. This space can then amplify the vibrations of a furnace that’s currently powered on.

Parts that are really loose can also cause rattling or knocking sounds. Aside from fasteners, a loose or unfastened blower fan may also generate such sounds. A detached panel, or one that doesn’t close fully, may also be to blame.

Totally Dislodged Parts

Banging sounds often indicate fallen parts, as in completely detached nuts and bolts. The noises come from the part being strewn around by the force or pressure of the furnace’s blower.

Foreign Objects Stuck in the Blower

Scraping or screeching usually means that a foreign object got trapped in the blower. As the fan rotates, it forces the object to move along with it. The object could then “scrape” against the sides of the blower, screeching along the way.

Broken or Damaged Blower Blades

A chipped, cracked, dented, or warped blower blade can also cause those scraping sounds. The “screech” may come from the damaged part running against the sides of the blower case.

Worn Motor Bearings

A furnace making clicking noise while running often signals worn motor bearings. Bearings reduce friction between moving parts, so they will wear out over time. When this happens, they’ll “thin” down and become loose.

As the motor runs, a worn bearing can vibrate and repeatedly hit the shaft or rod inserted in its hole. The can then result in clicking or soft knocking sounds.

Filthy Filter

Do you hear whistling coming from your furnace? If so, then a likely culprit is a filthy filter. The filter has become clogged with dirt that air can’t pass through it properly.

The good news is, you can fix this common furnace problem on your own — simply clean or replace the filter. This will also help make your heater “breathe” better, which can then boost its performance. A fresh filter can also help you trim your central HVAC energy costs by 5% to 15%.

Get That Furnace Making Noises Checked by a Pro Now

There you have it, the only guide you need when it comes to a furnace making noises. If it was only a one-time “loud noise”, then don’t worry, as that was likely the furnace coming out of its “resting” phase. However, if you continue to hear these noises, shut down your heater right away and contact an HVAC expert.

If you live within the Dallas County or nearby areas, we here at Infinity Texas Air can help. Ring us up now if you’re experiencing furnace issues, especially banging sounds.

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