Start by ruling out potential furnace problems
Before you start thinking about what sounds are coming from your ducts, you’ll want to rule out that the sounds are coming from your furnace. There are several different furnace sounds that signal potential trouble. Here’s why you need to keep an ear out for popping, screeching, and rattling.
The sound of a loud “pop” coming from the furnace could be a sign that the furnace is igniting too much gas in the combustion chamber. In most cases, the root cause of this issue is a defective gas valve or dirty burners. Basically, what you’re hearing is a (small) explosion inside of the furnace.
This is something that you’ll want to get checked out by a gas furnace professional. Eventually, the furnace flame sensor—a safety mechanism that checks for the presence of a flame to ignite the gas—may kick in, shutting down your furnace.
If you have an electric furnace, you’re not likely to hear this problem.
A loud screeching sound is not a natural part of a furnace’s cycle. It’s probably an issue with the blower fan’s belt. As these belts age and wear, they begin to fray and cause strange sounds.
If you’re hearing a distinctive screech coming from your furnace, it’s probably not something you want to ignore for too long. Call our team and have us out to inspect the system. Left untreated, these could lead to your furnace breaking down for good.
Chances are that you do not have a rattlesnake in your furnace, so the likely culprit of a rattle is something that is loose. The furnace produces a harmless low-frequency hum while in operation. Anything that’s loose—from screws and components to the heat exchanger itself—could start rattling from this natural vibration.
Again, this is something you’ll want one of our technicians to help you diagnose. The rattling of a loose part is typically an early warning for an impending breakdown.
Diagnosing the sounds made by noisy furnace ducts
Now that you’ve eliminated the possibility that the noise could be generated by your furnace, it’s time to turn your attention to your ducts. Here are some of the most common sounds made by noisy furnace ducts while your heater is running.
Once you’ve ruled out the sound coming from the furnace itself, the next likely explanation of a loud popping or banging sound is the ducts.
As hot air enters a cold duct, the metal expands and warps in response to the sudden temperature change. This leads to the metal “banging” as it shifts into place. This same phenomenon occurs when a duct, once filled with hot air, cools down after the furnace has been shut off.
This sound is pretty harmless, and it’s natural to hear it whenever your furnace turns on or off.
The rattling noise is most often caused by loose metal ducts that tend to knock against one another. This could be a sign that your ducts have leaks or gaps between them, which will ultimately have a negative impact on the performance and efficiency of your heating system.
As ducts age, the connective sealing between them begins to deteriorate or loosen. This isn’t going to cause a breakdown or anything, but it’s still worth having a Reimer technician look into this winter.
A sound of vibrating or shacking of the duct walls normally occurs due to the blockage of the return side airflow. This usually happens due to a clogged filter that results in a drop in the air pressure that makes the duct walls vibrate and shake.
A loud booming noise coming from the ducts typically emanates from the plenum where all the ducts meet. This connecting point tends to endure the greatest swings in temperature.
Inadequate expansion of joints or dampers contributes to the noise. What you’re hearing is a loud boom echoing through the supply ducts.
In some cases, you can hear a whistling or rumbling noise emanating from the ductwork. The whistling noise is normally caused due to excessive airflow through the ducts.
On the other hand, the rumbling noise could be due to pressure differences between the supply and the return ducts.