Noise Guide
Furnace Noises Explained: Banging, Rattling, and Hissing
Banging at startup can point to delayed ignition, where gas builds up before lighting. That pattern needs a prompt check, not a wait. Rattling can point to loose panels, a loose bl
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Banging at startup can point to delayed ignition, where gas builds up before lighting. That pattern needs a prompt check, not a wait. Rattling can point to loose panels, a loose blower wheel, or duct movement when the blower starts. Hissing can point to a gas or air leak path, and it should be checked promptly.
Humming with no blower spin can point to a capacitor or motor fault. Squealing on startup can point to bearing wear. Note when the noise happens: at startup, during heat, or at shutdown. That timing helps us narrow the fault on the visit.
Do not ignore a new noise that appears with a smell, a shutdown, or a safety trip. Those combined signs point to a safety check first, before any other work.
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Frequently Asked Questions
What causes banging at startup?
Delayed ignition can cause a bang when gas builds up before lighting. Call for a prompt check.
Is rattling serious?
It can be loose panels or a blower issue. If it is new and loud, call for a check.
What about hissing?
Hissing can point to a leak path and should be checked promptly.
Can humming mean a motor fault?
Yes. Humming with no spin can point to a capacitor or motor fault.
Helpful Sources
No Heat? Do Not Wait It Out
Licensed and insured style service. Mon-Fri: 7AM - 7PM, Sat: 8AM - 4PM, 24/7 Emergency. Serving Hendersonville and Sumner County, TN.