This might cause due to the striking of the bent blade to other parts of the fan.
Attic fan blades noise.
This sound could mean that something is stuck in the blower s fan blades.
If this common noise comes and goes with airflow that s an easy way to tell if this is the problem.
If you ve had your fan for a decent amount of time and are starting to hear noise from the motor area of the unit it may be time to lubricate the bearings.
Remove the current worn out bearings and replace them.
Besides being annoying the vibration could lead to loose.
Reason 1 the fan blades are bent upwards and or downwards which causes the fan to be out of balance and therefore wobbles creating a rubbing noise.
This can cause the fan to start making constant noise and in some cases even a loud squealing sound.
If the fan blades are imbalanced or bent they can hit against one another or against other parts of the fan.
While this situation might not be critical to the ongoing functioning of your furnace the obstructing object might be creating unnecessary wear and tear on the unit.
This will definitely produce noise while the blades are rotating.
Blades are essential parts of every fan and there is no difference with attic fan as well.
Attic fans also have small ball bearings that help lubricate the fan s movement.
If the blades are unbalanced you can balance them yourself.
The attic fan tends to makes a humming noise when it has a few blades and is running at a high speed setting.
Older models of fans are designed to be re lubricated over time and have pre installed places to fill with oil specifically to lubricate the bearings.
The vibration is most likely the result of a wobble in the fan that could be caused by some loose screws or a fan blade out of balance.
Solution 1 to fix this check that each fan blade is angled the same use a level and lay it on top of the fan blades bend the fans blades so that they all are angled the same.
In order to get rid of the hum you need to either operate the fan at a low speed or replace the fan with a new one that has more blades.