There are certain sounds your furnace should never make—at least if it’s well-functioning and in good condition. So when you hear your furnace making noise, it’s smart to pay attention. This is especially true if it’s making a strange noise you haven’t heard before.
When furnaces make strange noises, it’s a sign that something within the heating and cooling system is wearing out or broken. These strange noises might include humming, clicking, banging or rattling sounds. Let’s learn more about what it means when your furnace is making noises.
1. Making Banging Noises
If your furnace starts making banging noises, it’s time to contact a heating and cooling specialist to determine what’s going on. Depending on when the noise happens and for how long, it might signal several different problems with your furnace.
If the banging noise happens when you turn on the heat, it could mean the furnace won’t ignite like it’s supposed to. This could be caused by several different things. It might be a low gas supply or too much air mixing in with the gas. It could also be a faulty pilot light or dirty burners. A pro will be able to determine if one of these is the issue.
If the banging noise happens intermittently while the furnace is running, it may mean the ductwork connected to your furnace is expanding or contracting. If this is the case, you’ll most likely hear the banging noise somewhere in your home rather than coming from the furnace itself.
Occasional banging sounds caused by normal ductwork expansion and contraction is not something to worry about. But, if the sounds are loud or they happen a lot, it’s time to investigate. Common causes of this issue include blocked ducts, clogged air filters and ductwork that’s too small for the home’s HVAC system.
Hiring a pro to determine the cause of furnace banging noises is the most efficient way to get the heating problem solved correctly and completely.
2. Furnace Making Clicking Noises
If your furnace starts making clicking noises, it could be a problem with the system’s igniter. Similar to a car with a bad starter, when the furnace can’t ignite, it makes a clicking sound as it repeatedly tries to light up.
Sometimes, this is a simple problem to fix. The burners might be dirty and just need a good cleaning. The pilot light may have burned out and needs to be relit. Even if it’s easy to relight the pilot, though, whatever blew it out still needs to be resolved. This sometimes happens due to a draft in the area where the furnace is located. An HVAC specialist is the best person to determine the problem and how to fix it.
Problems with the furnace’s heat exchanger can also cause clicking sounds. This is a potentially serious problem since cracks in the heat exchanger can lead to a carbon monoxide leak in the home. A specialist can determine if it’s the heat exchanger that’s causing the clicking sounds.
A specialist is also the right person to call in cases of other serious or more complicated causes of clicking noises coming from your furnace. These include gas flow problems caused by an ignition board or valve that has gone bad, or by a broken flame sensor. Loose bearings in the furnace’s fan motor can also cause clicking noises. Any of these is a heating problem best diagnosed and resolved by a professional.
3. Furnace Making Humming or Buzzing Noises
It’s normal for your furnace to make a quiet, steady humming sound while it’s running. However, a loud humming or buzzing noise coming from the furnace could signal an electrical problem. The blower motor may need lubrication, or the inducer motor might have failed. Faulty transformers and blower motor capacitors also cause this type of furnace noise.
Electrical problems caused by a furnace should be checked out by a heating and cooling specialist as soon as possible. They can be dangerous if they aren’t addressed.
4. Furnace Making Whistling, Screeching or Squealing Noises
If your furnace is making a whistling, squealing or high-pitched screeching sound, it could be a problem with one of the blower components. It could also be caused by an issue with the flow of air through the system. If the sound is loud and sudden, it’s a good idea to turn the furnace off right away. That way, any failing parts will be less likely to break completely and cause bigger issues.
Blower motors have bearings inside them that start making high-pitched squealing sounds when they go bad. If the blower motor is simply old, it probably just needs to be replaced by a professional. If it’s going bad due to overheating, the cause of the overheating will also need to be diagnosed and fixed.
Other components within the blower can also go bad and cause loud noises. Sometimes, the blower wheel breaks, causing a loud, metal-on-metal screeching sound. This is uncommon, but it does happen. Fortunately, it’s a pretty quick and easy repair for a professional to handle.
Whistling noises coming from your furnace could be related to airflow problems within the system. Dirty air filters can cause airflow problems. So can dirty or clogged filters or ductwork. Changing your air filters is easy enough for most homeowners to do themselves. This is a regular HVAC maintenance task that should be done at least once every three months, if not more often. If replacing your air filter doesn’t resolve the whistling noise, it’s time to contact a specialist who can figure out what’s going on and fix it.
5. Furnace Making Rattling Noises
If tightening screws and panels do not fix the rattling noise, it’s time to turn off your furnace again and call in a specialist to investigate. Rattling sounds can be caused by more serious problems like cracks in the furnace’s heat exchanger. When the heat exchanger develops cracks over time, it’s a big deal. These cracks can release carbon monoxide into the home. This is a heating repair best handled as soon as possible by a heating and cooling professional.
Some Furnace Noises Are Normal
When your furnace starts making strange or loud noises it’s never made before, it’s a good idea to get help from a professional. But it’s also smart not to panic. Some furnace noises are perfectly normal, even if you’ve never noticed them before.
Most furnaces make a certain sound when they first start up, for example. They also continue making a mild humming noise the whole time they’re running. It’s also common for a furnace to make an occasional banging sound as its ductwork expands and contracts due to temperature changes.
The thing to look out for is when the furnace starts making a noise more often or louder than before. Sudden noises are also a potential sign of a problem. A trusted professional can determine whether the noise is coming from something normal or if it signals a problem that needs fixing.
Annual furnace maintenance check-ups by a professional are the best way to keep your heating and cooling system in great condition. A pro will be able to keep your system clean and in good working order. They can also spot problems as they start to develop, which helps to prevent bigger, more costly repairs in the future.
ABC Can Inspect and Repair Your Furnace
Instead of trying to diagnose and fix the problem yourself, our highly-trained professionals can come to check the problem out. Let ABC Home & Commercial Services’ professionals put your mind at ease about any sounds you hear coming from your furnace. Our experienced team members can make repairs to your furnace and are available 24/7 for emergency services. We even offer preventative HVAC maintenance too!