Why is my heater making noises?


There’s nothing quite like getting all snug under the covers on a chilly winter night with the heater running so your home is feeling extra cozy. Everything is perfect until your heater begins making an unfamiliar sound. Does this mean it’s time to get your heating system looked at? Heaters and furnaces are intended to function as quietly as possible. Most times, if you are hearing any abnormal sounds, such as whistling or rumbling, there’s a good chance there is a problem that should be resolved as soon as possible.

Here are the top most common HVAC & Furnace noises that require immediate attention:

  • Rattling
  • Rumbling
  • Banging
  • Whistling
  • Hissing
  • Screeching
  • Humming

If you hear any of these sounds coming from your heater or furnace, you should call a professional HVAC technician from FiveStar to come out and assess the issue at hand. Our certified heating and cooling experts are available for same-day servicing in Nashville and surrounding areas. 

Why is my furnace so noisy?

Here are a few of the most common reasons heating systems and furnaces make unusual sounds. 

  1. Ducts are too small or there are gaps in your ductwork

Type of sound: Whistling

Gaps in your ductwork will result in a whistling sound that is typically traced back to the spot where the ducts connect to the furnace. You may also hear this whistling sound if the ducts are too small for the amount of air flowing through them. To resolve either of these issues, you should rely on a professional. 

  1. Your air filter is clogged

Type of sound: Whistling

If your air filter becomes clogged, there will be a restriction in airflow that can create a sort of whistling or hissing sound. If you noticed the whistling more recently, you can try turning off your heater or furnace and removing the filter. If it is dirty with dust and debris, it should be thoroughly cleaned or replaced. Once you turn on the heating unit with a new or cleaned filter in place, try to listen carefully for any whistling sounds. In most cases, replacing the clogged filter will fix the issue. 

Please note that while it is safe to replace your own air filter, you should never attempt to perform any at-home furnace or heater repairs without professional assistance. 

  1. Your ductwork is beginning to flex

Type of sound: Banging

Your unit’s ductwork can begin to flex when the pressure shifts between the return and supply ducts. Another term for this issue is “oil-canning,” which essentially takes place when there is a fragile spot in the ductwork that is in need of reinforcement. Remember that older ducts are a channel for sound, so it can be normal to hear them from time to time. 

If the banging sound doesn’t go away, this is usually a tell-tale sign that your ducts are oil-canning. In this case, it is crucial to have a certified HVAC technician come out to assess and fix the issue carefully and properly. If you want to help, try to locate exactly where the banging sound is coming from.

  1. Delayed ignition due to dirty burners

Type of sound: Banging

When the inside of your furnace, especially the burners, become filled with dust and debris, the ignition can become delayed. Basically, instead of it starting up immediately, the gas begins to build up, creating a banging sound once it finally is able to light. This is one of the many reasons we recommend maintenance checks, as this is one of the things we inspect. If it has been a while since you have had your furnace properly cleaned, a routine servicing will usually resolve the issue. 

  1. A loose screw

Type of sound: Rattling

A rattling sound coming from your heater or furnace can either be a simple quick fix, or a more serious issue. If it’s an easy fix, tightening up a few screws will typically do the trick. When these screws become too loose they tend to be very loud. If you are wanting to perform this task on your own, all you really need to do is turn the furnace off and use a screwdriver to tighten each screw on the sides of your unit. Don’t hesitate to call a professional HVAC technician to come out and perform a routine maintenance check, and this will be taken care of for you. 

  1. Heat exchanger has a crack

Type of sound: Rattling

Improper air flow allows heat to build up inside the heat exchanger which can cause it to crack. A cracked heat exchanger is a more serious problem, as these cracks often lead to carbon monoxide leaks. That’s why it is important to routinely check your carbon monoxide detectors as well. If your carbon monoxide alarm ever goes off, everyone – including pets – should evacuate the home immediately. If you hear a rattling sound that doesn’t seem to be caused by any loose screws or parts, call us right away so that we can assess the situation, repair any issues, and keep you and your loved ones safe. 

  1. Loose blower wheel 

Type of sound: Scraping/Screeching

The blower wheel is the part of your unit that regulates air circulation, and sometimes it can become quite loose. When this happens, the wheel repeatedly bumps into the shell of the blower. If you are hearing any kind of scraping, scratching, or screeching sound, it is important for you to book an appointment with a professional HVAC technician as soon as possible. Ignoring the issue and continuing to use your heating system with a loose blower wheel will cause much more damage to your unit. Not to mention, the repair cost could also be significantly higher because of the extensive damage to both the wheel and the fan. 

  1. Malfunctioning blower motor

Type of sound: Screeching

The blower is what transports the heated air through your ducts and throughout the vents in your home. Blowers require proper lubrication to function properly. When the blower motor isn’t properly lubricated, it causes several other problems with the rest of your furnace or HVAC. If you hear a screeching sound coming from your furnace, we recommend turning it off immediately and contacting you locally trusted HVAC experts at FiveStar.

FiveStar HVAC Technicians will Repair Your Furnace & Your Noise Problem

Any sounds or strange noises coming from your heating system can be frustrating and annoying. But mostly, these are the warning signs that bigger problems may arise if the issues aren’t addressed sooner rather than later. The professional HVAC experts from FiveStar will carefully inspect each component of your furnace or HVAC system to identify the problem and provide you with the best solution. You can rest assured that once we finish, your heating system will be working as safely and effectively as possible. And the added bonus of having some much needed peace and quiet. 

Call FiveSTar today at (615) 382-8131