Your furnace is an important part of your home, it keeps you and your family warm in the winter, so keeping up with maintenance and cleaning is vital to making sure it can continue to do its job. As furnaces age various parts can be more easily broken or just function less optimally than they did when they were new. Sometimes your furnace may start making noises that it’s never made before. Or perhaps you’ve moved into a new place and have never had this type of heating system and you’re wondering “is that sound normal?” We’ll go over common furnace noises and what they mean, so you can decide if you need to get a technician in immediately.
Normal Furnace Noises
There are some noises that happen regularly that you don’t have to worry about at all. Most furnaces will make a noise when they start up, especially if they’re older. You’ll often hear a click or pop as it ignites and then a humming as it starts working. If the noise of your furnace starting up has changed over time to be more excessive that might be an indication there’s something off. Mention it to your technician next time they’re in for maintenance or cleaning.
Unusual Furnace Noises
Rumbling – A loud rumbling that may even shake the whole house could be fuel continuing to burn in the furnace even after the burner is off. This sound is important to have looked at immediately as the issue can cause carbon monoxide to be released into your home. Make sure your carbon monoxide detector is up to date. (Link to carbon monoxide detector blog)
Pops – Popping noises can be more challenging because they can occasionally be completely normal while other times they can indicate a problem. As your air ducts expand and contract in response to temperature changes, small pops when your furnace turns on are probably normal. However, a dirty burner can also lead to an accumulation of gas, which can result in small explosions that significantly harm your furnace. Contact a technician if the popping sounds are loud and persistent.
Clicking – As mentioned above, it’s typical to hear a click as your furnace ignites. But during the cycle of the furnace, frequent, excessive clicking can indicate problems.
Your furnace may have faulty wiring or a leaky valve if it is clicking but not turning on. Get your sensor checked if the furnace is repeatedly turning on and off. Additionally, a compressor or control panel issue may be the cause of constant clicking during cycles.
Whistling – Often caused by dirty air filters that haven’t been changed in a while. The little holes whistle with air when the filter is clogged or dirty. Make sure to routinely clean or replace your air filters or have a technician come in to do so.
Squealing – High-pitched squealing from your furnace may mean the blower wheel could need to be repaired, if it is broken, or it may require some lubricant to keep it functioning properly.
Buzzing – Your furnace may vibrate or make buzzing noises if parts become loose or separated. You should have a technician check everything over to make sure it’s functioning properly.
Grinding, Scraping, Clanking – Another blower wheel problem often sounds like a train chugging along on tracks. Another piece may have fallen loose or become jammed in the blower, or the wheel may have become detached and is now scraping or grinding against metal. Regardless of the cause, if you hear metal grinding or scraping, have a technician look into it as soon as possible before it causes irreparable harm, costing you more in repairs.
Thumping – A thumping sound indicates that the furnace’s larger, more central piece has come loose and is banging against the framework. If the blower wheel or motor is unbalanced, you could run into serious issues. If the noise sounds similar to something heavy bouncing around in your washing machine then you’ll definitely want to have your furnace checked out soon.
Booms & Bangs – One of the sounds you want to address right away is a loud boom, which is most likely, a small gas explosion within your furnace. It’s possible that your furnace isn’t lighting properly, causing gas to build up before it turns on and resulting in a larger-than-usual explosion. Booms and bangs are frequently caused by a furnace that hasn’t been cleaned in a while. Small explosions like these can lead to additional problems like damaged heat exchangers that can leak carbon monoxide. Have a technician check for repairs or cleaning if you continue to hear booms that resemble a muted gunshot.
If you hear any of the above noises you’ll want to contact a technician to have your furnace looked at as soon as possible. To prepare for your technician appointment make sure you can clearly describe the noise, maybe consider recording it on your phone if possible, just in case the furnace is not making the noise when the appointment happens, and try to identify any patterns with the noise, such as frequency, time of day, etc.
Letting a furnace run with broken parts can cause damage that may be more expensive to repair or may mean you have to replace your furnace entirely. Some noises can even indicate safety issues so you’ll want to be extra cautious to avoid harm. If you hear these noises in the winter you’ll also want repairs to take place as soon as possible so you aren’t left without heat for too long. Finally, the best way to keep your furnace running at its best is to have regular cleaning and inspections so any issues don’t get out of hand. You can learn more about our furnace servicing here.