HVAC
Why is my furnace making a strange banging, rattling, or squealing noise?
What’s likely going on
The specific sound actually matters: a squeal often points to a belt or motor bearing wearing out; a bang or pop on startup can mean a delayed ignition in a gas furnace; a rattle is frequently just a loose panel or duct connection. Very different causes that happen to sound similar to an untrained ear.
Is this a DIY job or worth calling someone?
A loose exterior panel is worth checking and safely tightening yourself. A banging sound specifically, especially from a gas furnace, is worth having looked at soon rather than waiting — delayed ignition is a real mechanical issue, not just an annoying noise.
Not sure, or ready to have someone take care of it?