We installed a new Hampton Bay 36" ceiling fan which replaced an existing light fixture. When the fan runs (on any speed) it produces a humming sound unlike the others we currently have in our house. Any ideas as to why and what might be done to stop it?
Thank you

Make sure all the parts are tight and any vibration isolating material included is being used. You may have to add some. See:

General ceiling fan troubleshooting and help FAQ- Ceiling Fans N More (http://www.ceiling-fans-n-more.com/ceiling-fan-general-troubleshooting-and-FAQ.php#6)