Why Is My Furnace So Loud?

After a long summer and warm fall in Texas, it , can be a bit unnerving to reignite your heater after months of dormancy. Homeowners can find this to be especially true if it is an older unit. If you hear loud noises upon startup, you may need to contact a professional HVAC technician. If you live in the Brazos Valley and need to service your heating or air conditioning unit, technicians at Barker’s Heating & Cooling are available 24/7!

Normal Furnace Noises

Much like starting a car engine after remaining dormant for a while, it is perfectly normal for your heater to make minor clicks and pop sounds when reignited. . A newer heater might have modifications to make it quieter than older ones. This can include added insulation for noise reduction or variable speed systems allowing them to “switch gears” and adjust the amount of heat pumped through your home’s vents.

These modifications reduce energy use, while older, single-speed systems typically either run at full speed or turn off completely.

Signs of a Problem

Regardless of your unit’s age or modifications, the sound(s) it makes are an easy indication if it is running properly. If your furnace’s noises are loud enough to be disruptive while you are inside your home there is potentially a problem that needs to be addressed. Isolating the sound to locate the source of the issue is the first step to finding a solution.

The following sounds are the most common causes for concern and may be heard during startup, while running, or when shutting off:

• Loud Pops and Bangs or Rumbling
• Thumping or Clanking and Scraping
• Grinding, Screeching or Rattling
• Squealing
• Continuous Clicking or Rattling
• Humming
• Loud Pops and Bangs or Rumbling

When a furnace begins a cycle and warm air makes contact with the cold, metal air ducts in your home, the ducts expand and contract in reaction to the temperature change and can produce a popping or booming thud noise. This sound does not indicate damage and is normal to hear each time, but can be prevented (duct insulation, sealing, replacement, etc.) if it is too bothersome. To learn more, be sure to discuss solutions with your local HVAC company.

Why Do I Hear These Sounds?

If you hear a popping/banging noise louder than this, possibly at the end of the furnace cycle, you may have dirty filters or blowers. This requires immediate repair, as the lack of airflow will cause gas and heat to accumulate and crack your heat exchanger and leak carbon monoxide into your home.

This loud booming noise may also be caused by an unbalanced air-to-fuel ratio or dirty burners, which can delay the ignition due to gas buildup and cause you to hear an explosion sound when the furnace ignition is turned on.

A professional HVAC technician should be contacted immediately if you hear these loud banging noises. A trusted HVAC team will be able to inspect the situation and make repairs.

Thumping or Clanking and Scraping

If the blower wheel is loose or unbalanced it may create a thumping sound, like an unbalanced spinning washing machine, or even a loud clanking or scraping (metal rubbing against metal) sound, which indicates a major problem. This should be addressed immediately by an HVAC technician and your unit should be turned off right away to prevent further damage until they arrive to inspect the system.

Grinding, Screeching or Rattling

If you hear grinding, scraping, screeching and/or rattling noises when starting your furnace, the blower motor may be the source.

The blower motor functions using the fan to force warm air from the furnace through your home’s air ducts. To maintain proper function and perform efficiently over time, the blower motor bearings require routine lubrication. If not lubricated enough the fan may seize up, resulting in this loud sound heard upon start up.

Squealing

If you have a furnace with a belt-driven fan, as opposed to a direct drive blower, a squealing sound during operation often indicates a loose or damaged blower/fan belt – this is common as it wears over time, especially if used heavily.

If the belt is not the source of the squealing, something more complex within the blower motor may be to blame. With so many moving parts housed within it, regular lubrication prevents them from becoming dry and ensures the unit is always performing in peak mode during the months it is needed most.

Although it is possible to adjust the blower belt yourself, replacing a belt should always be done by a professional technician who will inspect the belt to determine any necessary repairs or adjustments, especially if the problem is elsewhere in the unit.

Continuous Clicking or Rattling

It is normal for gas furnaces to make clicking sounds at the start and end of each heat cycle. However, if the clicking noises can be heard repeatedly throughout the duration of the heating cycle the compressor may be the cause.

Clicking or rattling may also be caused by a loose control panel or screw. To attempt fixing one of these loose items yourself, be sure to cut off power to your unit at the source before using a screwdriver to tighten them.

Humming

While a furnace runs it is normal to hear a low humming noise, but if it becomes louder during a cycle or wasn’t making this sound previously the fan or capacitor may need to be inspected by a professional.

What to Do?

If you hear any strange or loud noises coming from your furnace and are in need of a heating system repair, turn off your system and call the experts at Barker’s Heating & Cooling, available 24/7. We will dispatch a certified technician to perform a professional diagnosis and repair to get any Brazos Valley home back to comfort in the heart of Aggieland!

Barker’s Heating & Cooling also offers affordable, seasonal maintenance to identify minor issues before they become costly repairs and prevent problems from occurring in the future. Regular furnace tune-ups can prevent many of these noises, such as dirty burners or filters popping, dry components grinding, and loose belts squealing. Be prepared for the cold weather and schedule seasonal inspections each year to keep your unit safe, efficient and ready-to-heat!