Furnace Noises: What Do These Different Sounds Mean?

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All mechanical equipment makes some noise when running–your furnace is no exception. However, the scary sounds furnace systems make may be normal or indicate trouble. Learn what all of these different noises are, including the noises that are really a sign you need furnace repair service.

Scary or Weird Sounds from Furnace

Some scary sounds furnace systems make are indicators of system issues that need attention–sometimes immediately. Listen for these noises while your furnace is running, and call Apollo Home for help if you hear them.

what do different furnace noises mean?

Clanging Noises from the Furnace Blower Compartment

If your furnace is making a clanging noise from the blower compartment, then the blower motor fan belt is badly worn or has slipped out of place. If you’re not comfortable replacing a furnace fan belt, it’s best to call for professional help. Don’t wait until the belt breaks, as it can flap around and damage other furnace components inside the compartment.

Loud Clicking Noises from the Furance

A persistent, loud clicking in the furnace cabinet can be deadly serious. It can indicate a cracked heat exchanger that’s letting carbon monoxide (CO) escape. If you suspect this is the case, shut the gas valve, turn the furnace off at the thermostat, and call your HVAC contractor.

Squealing or Grinding Noises in the Furnace

If you hear a squealing or grinding noise from your furnace, it can point to worn or dirty motor bearings inside the furnace. If the bearings aren’t replaced, the motor can overheat and burn out, so it’s best to have the problem taken care of before you face a costly component replacement.

Booming and Rumbling Noises from Burners in the Furnace

If a furnace isn’t serviced and cleaned regularly, dirt and grime will build up on the gas burner and cause a booming or rumbling sound when it ignites. This dirt buildup can block the gas jets and prevent ignition, so have the burner cleaned and tested by an experienced pro to ensure its safe operation.

Normal Sounds from a Furnace

A home high efficiency furnace. Furnace Dual Stage Electronically Commutated Motors. Motor UpflowHorizontal Furnace Multi-Speed Two-Stage Energy efficient a humidefier and a water heater.

Now, sometimes the same type of scary sounds furnace systems make are completely normal. Below are normal furnace noises that you can expect during normal heater operation.

Furnace Popping Noises from Ducts

When the thermostat signals the furnace to start up, the blower fan responds and starts to pump warm air through the ductwork. The resulting increase in air pressure inside the ductwork can cause a popping or pinging sound when a furnace is first turned on. When ducts are new or recently cleaned, these sounds are more noticeable, but they’re not a cause for concern.

Brief Click Upon Furnace Startup

As mentioned above, clicking noises from your furnace that persist are a serious issue. However, a brief clicking at the start of a heating cycle is normal. You probably only hear it if you happen to be close to the furnace when it turns on. This is just the sound of the ignition turning on.

Chirping Noises at the Beginning of a Heating Season

Some chirping noises the first time you use your furnace each year are normal. This commonly happens in systems that have been out of use for a stretch of time. Allow the furnace to run for a bit–the sound is likely to go away. Though if it doesn’t, it’s likely some routine maintenance is all that is needed.

How to Prevent Furnace Problems

When you care for your heating equipment, you protect it from the scary sounds furnace systems make and the problems the noises indicate. Do the following to keep your furnace in top shape and prevent problems.

Preventive Maintenance Tune Ups

HVAC system

Furnaces need a professional tune up each year to help prevent problems, increase energy savings, and boost indoor comfort. With a regular Cincinnati furnace tune up from Apollo Home, our technicians thoroughly examine your system to identify potential problems and the sources of scary sounds furnace systems make. This allows us to take action and perform the right fix before further damage or danger is caused.

Change Filters

Air filters need changed on a regular basis. How often depends on factors specific to your home and the timeframe recommended by the filter manufacturer–it can be anywhere from one month to one year, depending on your filter. Cheaper filters typically need to be changed more frequently. Filters need to be changed to allow proper air movement through the system, which reduces stress on the components. Dirty filters burden the system and cause issues that create worrisome noises.

Clear Airflow Obstructions

A dirty filter isn’t the only thing that obstructs airflow. Check the vents and return air grilles in your home to ensure they are not blocked and allow air to circulate freely through your home and back to the furnace, as the system was designed to do.

Also, check the fresh air intake vents leading to your furnace to ensure there are no obstructions–they are located on the exterior of your home.

Get Heating Help from Apollo Home!

Apollo Home HVAC technician

If the scary sounds furnace systems make in your home are on our list of concerns, contact Apollo Home today to schedule furnace repair in Cincinnati. Keep your furnace well-maintained to prevent bothersome noises when you have your annual tune up performed!

"Ernie & Mike did a superb job on my new furnace and A/C installation. Despite having more than a day’s work to do, they came in and stayed until the job was done. They were organized, efficient, and protected the rest of the house well. Got both furnace and A/C installed the same day. Ernie was courteous, informative, and clearly knew his job better than anyone I’ve encountered before. The units look so good guests now get The Tour of our new system. Apollo is clearly not a fly-by-night company. I would recommend them to anyone in need of a new furnace and/or A/C."
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- Cassandra B.
"The team at Apollo exceeded my expectations. As a business owner, my attention to the details and commitment to providing excellent service is high. From the sales rep. to the installation team, everyone’s performance was outstanding. For example, the installation team went to great lengths to protect our floors, placing floor runners and across the wood floors and up the stairs. They even were spot washing walls upon their departure. I highly recommend this company."
- Randy B.
"We scheduled an estimate AND a tune-up. We knew something was wrong with our furnace, but hoped we could make it through the rest of the season. Upon telling Bill what our furnace was doing, he warned us immediately what the possible outcome was going to be; a cracked heat exchanger. He watched the flames roll backward, tested carbon monoxide levels, which were so high they meter’s last reading was 5,600 before saying “high”. He immediately shut it down, tagged it, and explained that with levels that high and children in our home he wanted off right away. He continued his inspection and showed us via a camera that not only was it cracked in multiple places, but had holes all over it. He gave us a few options for repairing it; his knowledge as well as genuine concern was beneficial and refreshing. Luckily we also scheduled an estimator, Micah, to come too and we were able to get costs between repairing and replacing (with several options). We decided to replace with a much higher efficiency furnace and one sized properly to our home. Hands down, not only did they both provide us great service and knowledge, but without sounding dramatic, they may have saved our lives. This was our first time calling Apollo, but it won’t be our last."
- Sarah B.
"Apollo is an excellent company. I always receive great service. Alex A. was professional and friendly. He kept me informed during the process of checking my furnace and heat pump to make sure they were working properly. The company makes sure you are notified who is coming and when they are on the way. All my interactions with the company have been wonderful."
- Beverly S.



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