Please contact our Technical Support Department at 800-637-1453 for installation assistance.
The HD80L does not require hanger bars.
You can not use the hanger bars with the 678.
The AR110 requires the MHB4 hanger bars. The MHB4's will work up to 24". If you have further technical or installation questions, please contact our Broan Technical Support Department at 1-800-637-1453 between 7:30 AM and 6:00 PM (CST) Monday-Friday.
Our fans are not designed to be installed in a drop ceiling.
Hi, PK. Thanks for your question. Hanger bars are designed for using with fans when the fan is not going to be up against the joist. If you are unfamiliar with using these bars, I urge you to contact our Technical Support group at 888-336-6151. Thanks, again.