How to Quiet a Noisy Furnace Blower?

If there’s one thing people living in colder climates have to thank for; besides the gable roofs and insulated walls, it’s the furnace blower. As the temperature outside starts getting unbearably cold, the constantly-running furnace blowers feel nothing less than a lifeline, keeping your indoors warm and habitable. But the non-stop operations hardly continue smoothly.

Furnace blowers are often accompanied by unsettling noises like squealing and rattling. While most of them are produced when the blower expels warm air into the house, the unusually loud noises often indicate a malfunction. But let’s not lose hope. We have identified six easy ways to quiet a noisy furnace blower.

To quiet a noisy furnace blower, deep clean your HVAC system from the inside out, along with the intake air ducts. Adjusting the fan speed also helps quiet the HVAC blower, but if the noise continues, lubricate the motor and add some insulation. If you hear a loud rattling noise, fasten the mounting screws and replace the wobbly and loose parts.

What Makes Furnace Blowers So Loud?

Despite consuming fossil fuels and being inherently loud, furnace blowers are the leading heating source in most US homes. The widespread adoption is partly due to the higher efficiency, extended lifespan, and low maintenance.

Be that as it may, the noisy blower ducts are still quite a nuisance. Not just that, furnace blowers emit countless unwanted noises, each of which indicates a different underlying issue. Here, we’ll discuss the five noises that demand your attention first:

Rattling Noise

Rattling describes forceful and often loud vibrations produced by loose and wobbly parts in a furnace. While it primarily indicates sloppy components, if the rattling intensifies, chances are some parts may have fallen off completely. You can’t know the root cause for sure without removing the case and taking a look inside.

Banging Noise

It’s normally coupled with a loud whistling or swooshing sound, highlighting clogged or leaky air vents, ducts, and filters. Cleaning and unclogging the vents will help reduce the HVAC fan noise, but in the case of leaks, you’d need to find a suitable replacement.

Rumble or Humming Noise

While these noises are generally associated with a faulty fuel ignitor, transformer, or capacitor, it’s hard to conclude without inspecting from the inside. Either way, a furnace blower making rumbling or humming sounds shouldn’t be taken lightly or ignored. Unless you have the required technical knowledge or expertise, consider calling in an expert technician.

Loud Squealing

Considering their intensity and unbearably high-pitch, squealing sounds never go unnoticed. It is either caused by a loose belt driven off the rotor. Try mounting the belt back on with a bit of lubrication, but if you struggle, don’t be shy of calling in a professional.

Scraping Noise

If you hear metal scraping against metal or some other component inside the furnace blower, either expect a wobbly motor mount or a loose pulley – each of which must be replaced. Try examining the furnace while it’s running to identify the cause better.

6 Ways to Reduce Furnace Blower Noise

While preparing your home for winter, ensuring the furnace blower is working smoothly is your top priority. If there’s some malfunction or the furnace is unusually loud, you’d prefer to know in advance instead of tackling the issue during icy cold temperatures. Anyhow, here are six easy ways to quiet a noisy furnace blower so you can get through the winter in peace.

1. Clean the Blower Fan and Air Ducts

Furnace blowers and HVACs are often installed in the basements, which makes them more likely to soak up dust and debris. Especially if they had been in hibernation mode for most of the year. This piled-up dust, blocks the return air vents and fan ducts, resulting in a humming and sometimes rattling noise.

Every furnace blower maintenance starts with a deep clean. Since return air ducts have mounted grills, they get clogged up quite easily. If that’s what is causing the rattle in your furnace blower, point a fast-blowing desk fan in the direction to free up the vents allowing air to circulate freely. Make sure to turn off the furnace and cover all other intakes to create maximum air pressure.

2. Adjust the Fan Speed

When installing your HVAC system, technicians usually set the fan speed at maximum levels to ensure optimum performance. Since the furnace blowers are new, they don’t give off much noise or rattle at the time. But as you prepare for the winter the second time around, the blower speed could feel strangely loud.

If your furnace blower rattles at high speed, try lowering the speed until the hum reaches desirable levels. And no, reducing the speed will not compromise the furnace’s performance or make the indoors grow colder.

3. Find Replacements for Loose Parts

Loose parts are not uncommon for a furnace blower. When the air compressor constantly blows warm air through the ducts – sometimes at enormous pressures – parts like belts and mounting bolts get loose and wobbly. The initial rattling may not annoy you as much, but when it’s emanated through your ductwork, it becomes too loud to ignore.

Before you call in a technician, look around to see if any belts or bolts have gotten loose in the furnace and ducts. If so, tighten the loose screws and anything that totters.

4. Fasten the Motor

If tightening the belts doesn’t seem to quiet the furnace blower, maybe the motor is at fault, or the fastening screws that hold it together. In this case, the rattling is backed by a loud scraping and is mainly produced when the motor starts up or shuts down. It indicates that a loose component is blocking the rotation of the motor.

Gather around your tools, unscrew the motor casing, and check if any parts seem out of place. Don’t worry if you’re an amateur; try propelling the moveable parts to see if it rubs against anything else in the furnace motor. Make sure the rubber mount is in place, and the mounting bolts are tightened and secured.

5. Improve the Insulation

Even the air movement will cause a loud howling if your furnace blower lacks proper insulation or padding. When forceful air currents pass through the ducts, it causes them to vibrate and rattle. Restoring the insulation in these parts might feel like a hassle, but it effectively reduces HVAC fan noise.

Instead of using conventional insulation padding, use foam sprays to fill the gaps and buffer down the rattling. Many soundproofing experts suggest infusing melamine foam alongside blower intakes to soak the vibrations. If you spot leaks in the ducts, use caulking sealants to block off the airways that would otherwise create a squealing noise.

6.Lubricate the Moving Parts

If your furnace blower remains shut during the off-season, chances are that the mechanical parts have grown dry and squeaky. Operating the furnace as it is would make scraping sounds of parts rubbing and sliding past each other.

Use the 3-in-1 motor oil to lubricate the axle and shaft or anything else that rotates. Give them a little spin before turning the furnace back on again. Proper lubrication would also help get rid of other squealing sounds.

Quick Tips to Quiet a Noisy Furnace Blower

If your furnace blower is being annoyingly loud, but you don’t have the resources to upgrade to a newer model, here are some quick tips to quiet your HVAC blower:

Regularly clean the intake filters to prevent them from getting clogged up with debris.
Check your air ducts for signs of damage or leakage that might be causing the squealing noise.
Considering installing white noise machines near your HVAC system to shun the hardcore noise.
Secure the motor mounts to keep them from wobbling while operational. Renew the rubber grommets if needed.
Examine the fan blades for any dents and damage which could cause them to clamor. If so, replace the blade with a new one of a similar size.

Noisy Furnace Blower – When to Call a Professional?

While most of the furnace blower noise issues can be addressed at home, leave things you aren’t familiar with, to the professional. Rumbling and scraping noise from an HVAC system is not something you should take lightly. If tampered with the wrong way, the furnace could blow up, which makes it critically fatal.

Receiving annual maintenance checkups for an HVAC system is mandatory, especially at the start of the season. Schedule a session with a professional technician before the due time to ensure your furnace blower is ready by the winter hits.