
Furnace Making Loud Noise
Equipment that has changed its voice is worth a look, and a bang at lightoff is the noise that shouldn't be left to run all winter.
When this becomes an emergency
- There's a hard bang from the equipment shortly after the call for heat starts.
- A screech comes up with the blower and fades when it stops.
- Something is knocking rhythmically the whole time the system runs.
- The equipment has gotten noticeably louder over the past few weeks.
What a pro does
Sorting a noise means pinning down exactly when in the cycle it happens, which is why the first questions are about timing rather than about the sound itself. A bang shortly after the call for heat is delayed ignition, and it's the one that matters most, because every event stresses the heat exchanger. Screeching that comes and goes with blower speed is a bearing or a belt. Rhythmic knocking during a run frequently turns out to be a blower wheel out of balance, sometimes from a bit of debris, sometimes from a wheel that has collected years of grime unevenly. Salt-laden damp air ages motors and bearings faster than dry inland air does, so bearings deserve early attention here.
Frequently asked questions
Furnace Making Loud Noise?
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