What causes loud furnace noises and how to quieten them
Furnace noise can be a nuisance and make it difficult to enjoy your home or perform tasks that require concentration. If your furnace is making loud, strange noises, it could indicate an issue that needs to be addressed. Knowing the causes of loud furnace noise and how to reduce them can help you keep your home comfortable and quiet.
What causes furnace noise?
There are several factors that can cause furnace noise. Small ductwork, dirty filters, faulty or loose blower wheels, and a cracked heat exchanger can often contribute to loud noises coming from your heating system.
Noise caused by ductwork
Ductwork can cause various noises including banging, knocking, popping, rattling, screeching, and whistling noises. These noises are often caused by air pressure, closed supply vents, and K-style elbows in the ductwork that expand and contract when the system starts up. To address these issues, you should have a professional inspect your ductwork and adjust any closed vents and K-style elbows.
Noise caused by dirty filters
Dirty filters can be another common cause of furnace noise. When your filter is clogged with dust and debris, it can result in a whistling or screeching sound. If left unattended for an extended period of time, dirty filters can also reduce the efficiency of your system and damage your furnace. To avoid this issue, make sure to change your filter on a regular basis.
Noise caused by blower motors and bearings
Rattling and screeching sounds from your furnace may indicate an issue with the blower motor or bearing. Both need to be regularly lubricated to ensure they operate smoothly. If you have an older blower motor, it may need to be replaced.
Furnace noise caused by delayed ignition
If your furnace is making a bang or boom when it turns on, it could be due to delayed ignition caused by dirty burners. This should be addressed by a professional who can clean or replace the burners if necessary.
Noise caused by a cracked heat exchanger
A cracked heat exchanger can be indicative of a carbon monoxide leak and must be dealt with as soon as possible by a professional. If you have any concerns about your furnace, it's important to call a professional immediately.
How to reduce furnace noise?
To reduce the noise from your furnace, you'll need to identify the source of the issue. For banging and knocking ductwork, you'll need to have a professional adjust and inspect the ductwork. If the filter is dirty, you should replace it. Issues with the blower motor or bearing can be addressed by lubricating or replacing those components. A bang or boom when the furnace turns on should be addressed by a professional who can inspect and clean the burner. Lastly, any suspected carbon monoxide leaks should be investigated by a professional.
How often should I have my furnace serviced?
Having your furnace serviced once a year is recommended to ensure it's running efficiently and safely. During a service appointment, a qualified technician will check your furnace for any potential problems and address them accordingly. This will help to prevent noise-causing issues from occurring in the future.
If you're noticing loud noises coming from your furnace, it's important that you take the time to identify the source of the issue and address it. Knowing the causes of loud furnace noise and how to reduce them can help ensure your home is comfortable and quiet.
Expert tip
Be sure to turn off the power to your furnace before attempting any repairs. This will ensure that you stay safe while addressing any issues with your furnace.
Your blower wheel comes face-to-face with moving parts and can become loose over time. As the furnace is running, this can cause rattling and screeching noises. To address this issue, you'll need to have a professional realign the blower wheel.
Ignition rods can start to wear out over time, causing them to make loud clicking or popping noises when they ignite. This should be addressed by a professional who can inspect and potentially replace the rods if necessary.
If your blower motor pulley has become misaligned or is worn out, it can cause an all-too-familiar squeaking sound. To address this problem, you'll need a qualified technician to check the pulley and realign or replace it if necessary.
Vent pipes are an essential part of your furnace, but they can become annoying when they start to vibrate and cause loud noises. To stop this, you can add insulation to the outside of the pipe or install flexible piping.
Dirty condensation pipes can cause gurgling and dripping noises. To fix this, you'll need to flush out the lines and ensure there isn't standing water in the pipe.
Expansion tanks are used to reduce the sound caused by the expansion and contraction of the water as it flows through the system. If the expansion tank is too large, it can cause loud thumping or banging noises. To fix this, you'll need to replace the tank with one that's the correct size.
Furnace fans can also cause noise. If the fan blades are bent in any way, they can create a loud humming noise. To fix this, you'll need to have the blades balanced or replaced by a professional.
If your furnace wasn't installed properly, it can lead to loud rumbling. To fix this, you'll need to have the unit inspected, and any existing issues fixed or adjusted.
Wiring problems can also cause various furnace noises. Inspecting the wiring should reveal any loose wire connections, which can then be tightened by a professional.
Vibration isolation pads are designed to reduce the sound caused by the vibration of your furnace. If they become cracked or worn, they will no longer be effective. To fix this, you'll need to replace the pads with new ones.
