The blower motor has bearings that can overheat or age, increasing wear and tear leading to loud noises. If your house is experiencing reduced airflow, the blower may strain to pull air which causes a whistling sound. Damaged or dirty air ducts, closed air vents, and dirty air filters can reduce airflow in your home.
While reduced airflow due to a dirty or clogged filter can make these sounds, a loose bolt or component can as well. Low airflow will strain the motor as it tries to draw in more air. Try changing the air filter or opening all the vents, but if there's still a high-pitched whistling sound, repairs might be necessary.
Ineffective belt: A worn-out or defective belt might produce a loud, screeching sound if the blower in your furnace is belt-driven. Airflow restrictions: The blower may have to work harder due to blockages in the ductwork, which will raise the noise level.
Loud Bangs, Rumbles, Knocks, or Booms
Loud noises like this are a sign of a build of gas in a furnace. The noise you hear can mean your heat exchanger is at risk of cracking. Even worse, it's a sign that something dangerous could happen if you continue to use your heater.
Thumps and bumping noises, like an unbalanced washing machine, often indicate an unbalanced blower wheel or motor. This is a serious issue that requires immediate HVAC repair. The blower wheel and motor are major furnace parts and you don't want them bouncing around.
Tighten the motor mounts and see if that solves your issue. If it doesn't, insulating the blower might be the best solution. If that doesn't work, then you may need to replace the whole blower. If the annoying sound is a screech, you might just need to oil the blower motor.
Booms & Bangs
When too much gas builds up in the combustion chamber and the ignition is delayed, your furnace experiences a small gas explosion. This can be caused by low gas pressure, clogged burners, and dirty equipment.
We're here for the long run. So if you hear a squeal, a new click, grinding, or popping when your furnace is at any point in the heating cycle, it's best to have a tech take a look and catch things early.
While costs can vary, homeowners can typically expect the following range: Standard Blower Motors: These might cost between $400-700, excluding labor. Advanced Multi-Speed or Variable-Speed Motors: These are generally more expensive, with costs ranging between $650-1250, not including labor.
A failing blower motor may emit unusual sounds. This may sound like screeching or squealing if it has bad bearings. You may hear a rattle or a banging sound if something inside the motor has broken or come loose.
If your furnace produces a loud humming or buzzing sound, there could be an issue with the motor. There may also be something wrong with the fan. It can be something as simple as a loose screw, loose door, or improperly installed furnace filter.
You should only hear a gentle whoosh as the burners come on. If the sound is too loud, it probably means that ignition is getting delayed so that there is too much unburned gas in the combustion chamber that's igniting at one time. The ignition system may need to be replaced, or the burners might need to be cleaned.
There are a variety of problems that can cause your furnace to produce loud noises. Types of noises such as scraping, banging, whistling, and popping may be a sign of a loose part, cracked heat exchanger, or dirty gas burners.
Tinnitus is the medical term for "hearing" noises in your ears. It occurs when there is no outside source of the sounds. Tinnitus is often called "ringing in the ears." It may also sound like blowing, roaring, buzzing, hissing, humming, whistling, or sizzling.
You'll probably have to remove an access plate to get at the ports. If the blower has grease cups instead of oil ports, remove the screw caps that cover the cups and fill the cups with bearing lubricant, which is available at automotive and hardware stores. When you lube the motor, you should also check the belts.
Undo the screws on the motor to remove the belly band. The rotation of the motor needs to match the direction of the fans, so position them accordingly. Attach the new motor to the belly band. Center the new motor on the fan wheel, fasten the bolts, and connect the capacitor.
Blower motors are designed to last just as long as your furnace itself, anywhere from 10 to 20 years. Just as with any HVAC system, the better maintained and serviced your equipment is by experienced HVAC technicians the longer it will last and the fewer repairs you'll face.
Problems With The Blower
A clogged or dirty filter may reduce airflow through your system and cause whistling noises as the air forces its way through the filter. Loose bolts or other fittings on the furnace may also cause a rattling or whistling noises. One final possibility is that your furnace has a gas flow issue.
If you are hearing a boom sound coming from your furnace, the combustion chamber and burners can become clogged from grime and build up.
Banging Noises from the Furnace Room
Simply reading the word “explosion” may cause a small panic, but it's actually a common problem that many homeowners experience. When the gas isn't ignited immediately, the gas starts to build up in the furnace until it finally reaches a flame and ignites. This causes a loud BOOM.
A furnace explosion is a rapid uncontrolled combustion of fuel in the combustion chamber or exhaust uptake of a boiler resulting in high overpressure. The basic cause of this is the ignition of an accumulation of unburned fuel at some point in the system.
Delayed ignition is when that gas isn't ignited immediately, allowing the gas to build up in the furnace. The gas keeps building until—BOOM—it reaches a flame and finally ignites, causing a small explosion in your furnace.