Don't Let Your Heater Go "Bump" in the Night!

Beware of Spooky Furnace Noises

While ghosts, ghouls, and goblins may all go bump in the night, when the heater makes that noise, it can be a much scarier problem. Any noises coming from the heater indicate that the heater isn’t running as smoothly and efficiently as it should be, which can indicate a bigger problem on the way. To better identify those sounds and what they may mean, local experts have put together a list of three of the most common and likely causes.

Grinding or Scraping

If there is a grinding or scraping noise in the home, especially during the fall and winter, when the heater is used more regularly, it’s probably not paranormal… it’s likely a problem with the blower wheel or motor.

Often, it’s simply a case of the bearings in the furnace being dry and needing more lubrication to function efficiently without grinding. The blower wheel is an essential part of the furnace, as it is the part that pushes the air both into and out of the HVAC unit. If it isn’t working efficiently, it won’t just be noisy, but it will also be far less efficient. This can lead not only to a total furnace breakdown but also to increased energy bills.


Banging is one of the scariest noises that a heater can make. It’s so loud and abrupt that it’s impossible not to sit up and pay attention.

However, that banging usually has a specific cause. In many cases, banging coming from the furnace is actually an air duct problem. All air ducts, especially those made out of metal, will naturally expand and contract with the temperature change. Older ducts can’t keep up as well and will bang and pop as air and heat pass through them. Frequent banging may be a sign that they need to be replaced entirely.

Another frequent cause of banging coming from the heater is dirty gas furnace burners. Dirty burners can lead to an accumulation of gas, which can cause the heat exchanger to crack. If that happens, the furnace will need to be serviced immediately. Don’t ignore banging- contact an HVAC technician right away.


Unexplained screeching noises are terrifying, no matter the time of year.

Screeching from the heater is likely related to one of three things - issues with the blower motor, problems with the blower belt (like fraying), or issues with the shaft bearings. Much like a grinding or scraping noise, this problem isn’t necessarily immediately dangerous but can lead to much greater problems if not addressed.

The good news is, most screeching noises are due to easily fixable problems. Contact an HVAC technician right away for service and avoid larger, more costly issues down the road. All of those components are essential to a functional, efficient furnace. Having just one of them develop problems can cause catastrophic issues in the entire unit.

About Rosenthal Heating & Air Conditioning

Rosenthal Heating & Air Conditioning is Southeast Wisconsin’s trusted name in HVAC service. They are focused on homeowner comfort and safety. Since 1995, their expertly trained and highly skilled technicians have been taking care of the area with friendly, professional, knowledgeable service. They are NATE Certified and have EPA Certified Licensure.