The noise of exhaust fans is typically measured in sones. An extremely quiet bathroom fan will have a sone rating of 1.0 or lower, where a sone rating of 4.0 is extremely noisy. There are several more factors that can cause noisy bathroom fan exhaust:
- In-duct fans tend to be quieter than ceiling mounted fans.
- The location of bathroom exhaust vents and the configuration of ductwork can cause fans to be noisy. Keep venting turns gradual. Do not create sharp bends in the ductwork.
- Larger venting will keep fans quieter. Use four inch venting rather than three inch venting.
- Rigid piping transmits more noise than flexible duct work. Look for noise-muffling duct materials.
- Using nails instead of screws in fan installation can create noise once the nails begin to loosen and vibrate.
- Keep the bathroom fan clean. Dirt and debris can accumulate over time to keep your fan from operating efficiently.
- Consider installing a bath fan with a timer to keep fans from running longer than 20 minutes.