The Furnace Is Making a Banging Noise – Should I Be Worried?
Is your gas furnace making a loud banging or thumping noise when you turn it on? If so, you know exactly how concerning those noises can be!
At Minnick’s, we commonly receive calls from homeowners describing startling noises coming from their heating systems.
It’s no fun worrying that something is wrong with your heating system – and that’s why we’re here. We want to give you the peace of mind you deserve when it comes to heating your house. Let’s dive right in!
There are several things that can cause your furnace to make a loud banging sound when it turns on, but typically, your furnace is most likely experiencing what is known as a delayed ignition. In this article, we will cover everything you need to know about delayed ignition and what you need to do to fix it and protect your system and home from damage.
Defective Ignitor
Are you hearing a banging or booming when your furnace burner cycles on? Learn the cause (and what you can do about it), so you can get back to binging Netflix in peace.
Delayed ignition. When everything is in working order, your pilot flame or electric ignitor will ignite gas flow from the burner the instant your thermostat opens the gas valve. Even the slightest delay causes a puff of unburned flammable gas to stay in your furnace’s combustion chamber.
When that cloud lights up behind schedule, loud sounds radiate throughout your metal furnace. The sound is amplified as it bumps along through your ductwork.
You now know why it sounds like there’s a rogue drummer running loose in your ductwork. However, you may be wondering what’s causing the delayed ignition in the first place.
Here are the common reasons why furnace ignitions get delayed:
- Defective ignitor
- Weak flame on pilot light
- Burner malfunction
- Low gas pressure
The Fix
You’ll need to first narrow down why your ignitor is delayed before correcting the problem. Going through the checklist may require shutting down the furnace wall control to safely access wires and valves in the control panel. Get an expert to help you get a quick answer safely.
The good news is that the same problem that’s causing the banging and booming may actually be making your furnaces less efficient. You might have a lower energy bill to look forward to after the right part is cleaned, readjusted, or replaced during a furnace repair call.
Expanding & Contracting Ductwork
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You’ve just fallen asleep when a loud banging sound wakes you from your slumber. You drift back into dreamland a bit later, only to be awoken again. What is the cause of these awful intermittent furnace noises?
Why It’s Happening
Blame this one on expanding and contracting ductwork. It happens because of positive and negative pressure caused by heated and cooled air being pulled through your ducts.
The Fix
While intermittent banging and booming won’t necessarily cause problems, there are fixes if the sounds are disruptive. The first is to fortify the flimsy sheet metal used for most ductwork with heavy-gauge ductwork that has more stability in extreme temperatures. The second is to have round ductwork installed in place of hard edges for smoother expansion and contraction.
Do you have mice in your walls or a banshee in your backyard? Nope, that’s just your furnace making a horrible high-pitched, whistle-like squeal. But don’t worry, there’s an easy solution.
Why It’s Happening
Unlike a dry squeal that just means a bearing or belt is worn, high-pitched squealing usually means an airflow issue. What you’re hearing is your furnace’s blower struggling to take in enough air.
Here’s why your blower might be struggling with air intake:
- Dirty air filter
- Closed heating vents
- Blocked heating vents
The Fix
Check that vents are open without obstruction. Next, replace your air filter.
Blower Motor
Last but certainly not least on our list of problematic furnace noises is humming. If you’re hearing a constant humming or low-frequency buzzing, you can be semi-certain your home is not under attack by rabid hummingbirds. However, it may mean your furnace is failing, and you should have it looked at ASAP.
Why It’s Happening
While buzzing is one of the more low-key furnace sounds, it often ends up being the most serious. Humming often means a major electrical component of your furnace is failing.
This includes:
- Blower motor
- Blower motor capacitor
- Inducer motor
- Transformer
The Fix
Consider this an electrical problem that requires caution. Bring in a furnace pro to carefully look for faulty or aging electrical furnace components.
