Why does my furnace make a noise when it shuts off?

Typically, when a heater makes a loud banging noise when it turns off, it’s the sound of metal contracting. Once the heating cycle stops, the sheet metal of the ductwork and the metal panels of your furnace cool and contract, producing a ‘bang’ or ‘pop’ that you hear inside your home.

When should I worry about my furnace noise?

Rumbling. If your furnace completes a cycle but produces a loud rumble through the house, this is a cause for concern. It could be fuel is continuing to burn in the combustion chamber even though the burners are shut down. Problems with burners, pilot light, or flame sensors are possible.

Why does my heating ductwork make banging noises?

WHY ARE MY AIR DUCTS POPPING AND BANGING? One of the main causes for these loud noises are differences in pressure between the supply and return ducts. Another common cause is expansion and contraction due to changes in temperature.

Is it normal for furnace to be loud?

A dull hum is normal while your furnace is running. But if you hear a loud humming or buzzing sound coming from your furnace, it usually means your furnace has an electrical problem. The most common electrical issues that cause a humming or buzzing sound include: A failing blower motor capacitor.

How do I stop my heating ducts from making noise?

What can you do? Short of covering all your ducts with fiberglass insulation, or opening them up and inserting acoustic duct liners, the best you can hope for is a modest reduction in the noise. Use rubber pads to isolate ducts from wood.

How do I stop my furnace ducts from banging?

CHECK DAMPERS AND ACTUATOR Dampers can either be open or closed. Check the dampers on the supply side of your ductwork and try opening them up one at a time to see if this reduces the popping and banging noises. You can also adjust the actuator inside of the duct dampers up or down to reduce the duct noises.

How do you know when it’s time to replace your furnace?

Heating8 Telltale Signs Its Time to Replace Your Furnace

• The Age of Your System.
• Rising Energy Bills.
• Excessive Dust, Dirt, Soot or Rust Particles.
• Home Humidity Problems.
• Furnace Becomes Unusually Noisy or Develops Rattles, Buzzes or Hums.
• Furnace Has Visible Signs of Rust or Cracks in or Around System.
• Frequent Repairs.

What does a bad furnace capacitor sound like?

Open the access panel to the furnace and listen for a relatively loud humming noise. If you hear that sound and it doesn’t stop, there’s an electrical difficulty. If you hear a “clicking” sound when the capacitor kicks in, that’s a problem too.

What does it mean when your furnace makes a noise?

Normal sounds you may hear are tiny little pops or hums as the furnace runs. However, when your furnace is noisier than usual or you start hearing a noise you have never heard before, this usually indicates that there is something wrong with your furnace and it may be time to talk to your heating technician about some maintenance and repairs.

Why does my Lennox Furnace make a popping noise when it shuts down?

Another cause could be the fan off (delay-off) setting on the control board being too short. This is the amount of time the fan runs after the burner shuts down. With the Lennox, the factory default is 90 seconds.

When do you know something is wrong with your furnace?

However, when your furnace is noisier than usual or you start hearing a noise you have never heard before, this usually indicates that there is something wrong with your furnace and it may be time to talk to your heating technician about some maintenance and repairs. Here are 3 furnace noises that you should not ignore.

Why does a dirty burner cause a furnace to explode?

Having dirty burners in your furnace can cause a delay in ignition. So the gas will build up instead of the gas igniting immediately. When the gas finally builds up enough the spark will finally ignite all that built up fuel and cause a small explosion inside your furnace. This needs to be fixed by a qualified HVAC technician.