humming noise

[pama]

Why does my wood stove fireplace insert hum when I close the damper?

 

[David.Ervin]

Probably a sympathetic vibration from the blower. I had a really nasty rattle in my insert like that until we added an extra nut to hold down the blower.

If you post what kind of setup you've got, I'm sure somebody will jump in with a more specific answer than I can provide.