Oh the Weather Outside is Frightful… What Heater Noise Can Tell You About Your HVAC Unit

Oh the Weather Outside is Frightful... What Heater Noise Can Tell You About Your HVAC UnitYour HVAC unit is working best when you’re not aware it’s working at all, humming away quietly to keep your home comfortable. But like any complicated machine, it might begin to fail (for seemingly no reason!). There’s a lot of general guidance for home heating best practices, but you may find yourself in the dark when things actually go wrong.

One major indicator of HVAC unit problems is an unusual heater noise. If you start to feel your heat changing and are hearing heater noises you’re not used to, something may be amiss.

Repairing an HVAC unit is a difficult task, one that is best handled by a professional. That being said, an informed owner is a savvy homeowner. Just because you may not be able to fix your own heater doesn’t mean you shouldn’t have an idea of what’s going on. Different sounds can actually indicate different problems, so if you listen carefully, you may be able to puzzle out the issue yourself. If you’re hearing new kinds of heater noise, here’s what might be going on:


A sharp whistling sound can be an irritating heater noise, but it can actually be quite easy to nail down. If you can find the source of the whistling, you may be able to deduce the root of the problem. Turn your heater on and wait for the sound to start. With some careful listening, you can pinpoint the source of the whistle. If it seems like it’s coming from your ductwork, it’s most likely that air is escaping through gaps or holes in the ducts themselves.

If not, the heater noise might be caused by your air filter being clogged. It’s a common problem. Your air filter is there to catch particles flowing through your HVAC system, after all. If left unattended, though, you could be dealing with more serious problems down the road. If you think the whistling may be due to a clogged air filter, all you need to do to test it is pop it out and turn the unit back on. If the whistling is gone, there you have it. All you need to do is replace the filter.


If your heater is making a rattling noise, then something may have come loose within the system. Frequently, you’ll find the source of the heater noise to be your ductwork. As you use your HVAC system, the screws and supports keeping your ducts in place can naturally become looser. Sometimes, all that needs to be done to solve the problem is to find the loosened ducts and tighten the screws.

Rattling can also mean that your ducts are vibrating up against the structure of your house itself as they transport air through the house. That’s a more difficult problem to fix, as someone will need to get into the bones of your home. Once you have eyes on the ducts in question, all you need to do is place something between them to cushion the ducts from whatever they’re rattling against.


Humming can mean a mechanical problem within your HVAC unit. The usual culprit is an under-lubricated blower fan in the unit itself, the friction causing the endless hum. The first thing you’ll need to do to check is to turn off your system. Be sure to give the blower motor plenty of time to cool off before you get near it. The friction isn’t just causing your HVAC to hum; it’s also generating a lot of heat. It won’t be safe to touch until a little while after you’ve shut it down, so take a moment before looking any deeper into the problem. Once it’s safe, properly applying lubrication may solve the problem.


A high-pitched squealing or screeching coming from your HVAC may be annoying, but luckily, it doesn’t typically point to a serious problem within the unit. Said heater noise is likely being caused by a problem with the bearing, belt, or motor within the unit. Unless you happen to be a trained HVAC repair technician with spare parts laying around your home, it’s unlikely you’ll be able to solve the problem without the direct aid of a trained professional.

Even though squealing doesn’t indicate a more dire situation in your HVAC system, you should still have it fixed as soon as you’re able. Problems like this can lead to more malfunctions down the road, and it’s important to take preventative measures whenever possible.

Banging or Booming

A loud bang or boom isn’t an uncommon sound for a heater to make but should be taken seriously all the same. While it can be benign, it can also be a symptom of a more dangerous problem. Your best bet to tell the difference is to figure out where the heater noise is coming from.

If the source is the ductwork, it’s likely being caused by the metal siding expanding or contracting as air is forced through the system. In that case, you don’t have much to worry about. It just comes down to your ductwork having too much pressure put on it, so once you find the source of the pressure, the problem is easy enough to solve. Usually, all you need to do is check to see if your home vents are open or if your air filter is clogged.

If the noise is coming from the heater itself, though, you may have a bigger problem on your hands. A boom coming from your heater a little after your system turns on can indicate that you have a delayed gas ignition. Instead of the gas lighting right away as normal, it builds up in the furnace. When the gas does actually light, it causes what is essentially a small explosion inside your system. This is not only harmful to your HVAC system, but it’s also a danger to you and your family. If you think you may have a delayed ignition, it’s vital you turn off your heater right away and seek the help of a professional.

If You Do Need a Hand

Managing your home can be a daunting task, but hopefully, this crash course has made you feel a bit more prepared to handle any unusual bumps in the night. If you still have a heater noise that you just can’t explain, don’t hesitate to reach out to a trained expert, like Entek. With a basic understanding and the help of a technician, you can tackle any problem you might find.

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Susan Said… WHAT?! is your guide to style for the way you really live and was named one of the Top 50 Beauty Blogs in the World by RebateZone.com. You’ll find everything from fashion and beauty, to gorgeous gardens, stunning interiors and DIY projects, plus the latest ideas for holiday events and parties of all kinds. Editor Susan Conforte McNeill is an author, entrepreneur, and co-founder of the Delaware-based literacy organization Success Won’t Wait

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  1. 2

    This is good info. At our complex, the boiler was shaking and causing the upper floors to shake, it went on for six months until they fixed it. Very scary, not sure what the entire problem was, but they have no maintenance agreement, just wait until a catastrophe happens.

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