Exhaust Fans – Installation Tips / Kitchen and Bath
I know this sounds crazy, but be sure to carefully follow the instructions that come with your fan. The single biggest reason for problems with exhaust fan installations is failure to follow directions. It only takes five to 10 minutes to read instructions.
Be sure to use the recommended ductwork. Don't mix and match sizes, as you will affect the static pressure load on the fan!
For kitchen exhaust fans, be sure to use metal ductwork! Tape all joints with high quality duct tape. Fires are a real possibility.
Try to locate fans so that the duct run is as straight and short as possible. Remember, a 90 degree bend or elbow is often equivalent to 10 linear feet of duct run. Most fans have a limit to the total length of duct. Pay attention to this number!
Each exhaust fan has a discharge port where the exhaust air leaves the fan. This discharge port may be three, four, five or six inches in diameter. Do not, on your own accord, reduce the size of the duct between this port and your exterior termination cap.
I have found that it is often best to vent fans and dryers through the roof. I urge you to watch this video of mine to see how easy it is to install the correct vent-cap flashing on a roof. Have no fear - if done right you will have no leaks.