The Complete Guide to Furnace Rattling and How to Prevent it

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What is Furnace Rattling, and Why Does it Happen?

Sounds coming from the furnace are never something a homeowner likes to hear. Furnace rattling is a common problem in old furnaces. There are many reasons why it occurs, some of which are more serious than others.

This article reveals the most common causes of furnace rattling and how to fix them.

HVAC technician inspecting a furnace rattling

Different Types of Furnace Rattles

A rattling furnace is a common issue that various factors can cause.

Loose or worn parts cause the most common type of furnace rattling noise. These rattles are usually more pronounced when the furnace is running, but they can also be heard when it is off.

If it’s a clicking sound you’re hearing from your furnace, this could be caused by a few things.

For example, the ignition system may suffer a malfunction that requires furnace repair. (This is likely the culprit if you experience furnace rattling when starting.) Consider contacting a professional HVAC technician to pinpoint this issue and other rattling sounds.

Top 10 Reasons Why Your Furnace is Rattling

If you notice that your furnace is making a continuous rattling noise, it may be time to call in an HVAC expert. Here are some of the most common causes:

1) Loose bolts

Turn off the power to your furnace, then check for loose bolts on the cabinet or in the access hatch. Bolts can become loose over time and may need a little tightening with a wrench to resolve the rattling.

2) Faulty blower motor

Over time, fan belts in blower motors can become cracked or frayed, causing a rattling noise. Fixing this issue is not a DIY job. Be sure to contact an HVAC professional immediately to avoid significant damage to your furnace.

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3) Broken or dirty motor fan blades

Blower fans accumulate debris and wear down over time. Left unresolved, these fans can wear down and cause damage to the motor or motor bearings.

4) Cracked heat exchanger

Because of the near-constant exposure to heat, heat exchangers are prone to cracking. Cracked exchangers can leak carbon monoxide, so this is an issue you don’t want to neglect.

5) Clogged air filters

Routinely replacing air filters prevents dust and debris from entering your HVAC system. Dirty filters can lead to defects that cause furnace noises.

6) Dirty burners

Dust and debris can accumulate on the burners in a gas furnace. Be careful not to tamper with gas lines; this is a job for your HVAC technician.

7) Loose cover panels

If you own a high-efficiency furnace, hearing rattling noises could mean that the panels that cover your furnace have come loose and need tightening. You can perform this task yourself or call a professional to take care of it.

8) Failing pilot light

A clicking or rattling noise is normal when a furnace first ignites, but if it continues, there’s likely a pilot light malfunction. The ignition system may have low gas flow or other issues that need attention from an expert.

9) Loose or warped ductwork

This may be difficult for the average homeowner to determine, but an HVAC technician can inspect the ductwork for open spots that can cause rattling.

10) Defective inducer motor

The draft inducer purifies the air in the heat exchanger, which means it can wear out and build up soot over time. One clue that the inducer motor may be the cause of hearing furnace noises is if it’s making a tapping sound.

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How to Prevent the Rattle Before it Happens

The best way to prevent a furnace rattle is to schedule routine maintenance services. Fan belts, loose bolts, ductwork, and more are all inspected during professional HVAC repair services.

A constant rattle represents a problem that’s been put on the back burner, an annoyance that keeps popping up and never seems to disappear.

Noises are a furnace’s way of letting us know there’s a problem requiring our attention. It’s essential to address heating and air conditioning noises promptly to avoid unnecessary damage or a complete HVAC breakdown. 

How long does a furnace last? Find out here.

Avoid Furnace Rattling Sounds in the Future

Furnace noise is a common complaint in the HVAC industry. As you’ve read above, such noises can result from many factors. If you own an older furnace that continues to make noise, it’s likely time to call a professional to discuss furnace replacement. Old furnaces, particularly gas furnaces, can become a safety hazard when carbon monoxide leaks are a potential.

The good news is newer furnaces operate much more quietly than older models. And if you choose to keep your old furnace running, regular inspections can identify and solve issues before they become annoying or, even worse, terribly expensive. Whatever path you choose to take to heat your home, the experts at Home Comfort USA are here to educate and serve you.

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