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.
Thumping sounds that come from your furnace could indicate that a motor or blower wheel is out of balance. This could cause big problems for your mechanical equipment down the road. It's best to have an HVAC professional take a look and fix a small problem before it becomes a big one.
We always want to stress that anything involving the burners and possible gas emission, should be addressed sooner than later. If you are hearing a boom sound coming from your furnace, the combustion chamber and burners can become clogged from grime and build up.
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.
Banging Sounds Coming From the HVAC Ductwork
It is the result of expansion and contraction in the duct walls as internal temperatures rise or fall. This type of noise can also be the result of pressure changes within the ducting.
Since your heating system works in a closed loop, water travels from the boiler to the line of radiators and back. End-of-the-line radiators are being warmed by water that's already released a lot of its heat. The banging noise occurs when new hot water is released into a radiator that contains standing cold water.
Popping. If you hear popping sounds and you don't have a bag of popcorn in the microwave, you could be dealing with dirty furnace burners or damaged air ducts. When the burners are dirty, the buildup prevents them from igniting, which causes too much gas to build up, making a popping sound.
If you hear similar clanging or loud banging noise in the walls, it can be a sign of clogs or air pressure in the system called a water hammer. If you don't resolve the problem, it can cause damage to the pipes, so consult a professional.
Banging Sounds
If your furnace is making a loud booming or banging noise, the problem may be caused by a small gas explosion that happens when there's a delay in ignition. Gas can build up in your combustion chamber when the gas burners in your furnace do not ignite on time.
If your furnace suddenly produces loud, sudden banging or booms, you should call an experienced technician as soon as possible. These sounds could indicate stuck ignition, a potentially dangerous situation involving carbon monoxide which is deadly.
At times, it may sound like an off-balance washing machine; at others, you may hear noises resembling something more like that of a jet engine. If you notice your furnace making a rattling or rumbling noise, or other major changes to the way it typically sounds, you're not crazy.
A loud, regular thump or thud that sounds continuously as your furnace is running is probably an unbalanced blower wheel or motor. You'll hear the sound of the rotation as the wheel or motor whirls unevenly in your system. You should have the part balanced as quickly as possible to avoid further damage.
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.
This phenomenon occurs as a result of the temperature changes in the ducts. As cool air passes through a warm duct, the metal of the duct contracts and makes a popping sound. Similarly, as warm air passes through a cool duct, the metal of the duct expands and creates a popping sound.
In an electric furnace, if the thermostat wire touches the metal frame of the furnace, it can cause a blown fuse. When the wire touches the metal frame, it can deliver a higher voltage than the wires are meant to handle. This will cause a fuse to blow.
In newer, high-efficiency systems, exhaust fumes are vented from the unit but can produce condensation from moisture in the air. If your furnace struggles to drain this condensation properly, it can cause gurgling, dripping, or bubbling sounds.
Clean or Replace the Filter
The pressure will decrease once the heating cycle stops and the metal panels will 'bang' and 'pop' as they contract. To reduce the noise, clean or replace the filter as needed, and check it every month during the heating season.
Loose or Unsecured Parts: Over time, components within your air conditioner can become loose due to regular wear and tear. When these parts move around, they can create banging noises as the unit turns off and on. Duct Expansion and Contraction: Your ductwork can expand and contract with temperature changes.
Furnace Screeching or Scraping
The blower fan may have come loose, letting the blades drag across the furnace casing. A scraping noise can also indicate other parts of the system have loosened. If you are unsure of the cause of the noise, turn the furnace off and have a technician come and take a look at it.
More often than not, a banging noise from your boiler is traced back to a process called “kettling”. This is usually when limescale builds up on the heat exchanger and restricts the flow of water to the point where it literally boils.
Most often, it's your home's plumbing system. It may be due to fluctuating water pressure issues, loose plumbing pipes, or a faulty valve. To help find the problem and solve it, the first thing you need to do is take note when you hear the banging noises.
The air conditioning compressor is a key part of the AC system. It's responsible for circulating refrigerant throughout the unit. If your AC unit's compressor is starting to fail, it can cause the unit to produce a popcorn sound. Another sign your compressor may be failing is if your AC unit is icing over.
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.