Unlike the belt driven fans in case of a direct drive fan there is lesser energy loss.
Direct drive vs belt drive attic fan.
Thus the fan blades will rotate at the same speed as the motor rotates.
When compared to belt drive fans which require belts sheaves and bushings direct drive is just plain simpler and maintenance folks tend to lean toward direct drive for daily maintenance.
Sizing a whole house fan.
This is because of the fact that the amount of friction is greatly reduced in case of this fan when the fan is operating.
I fantasized building a small shack outside my house and setting the attic fan in the shack and running a duct up to the attic and through the same vent as an attic fan.
Direct drive models are the most do it yourself friendly because for most no attic joists need to be cut.
With a belt drive the fan speed can be easily raised or lowered but there is belt and bearing maintenance to consider with a belt drive there are 2 additional bearings.
Greater efficiency is the biggest pro of direct drive fan configurations.
That would be quiet but would look like a mess from outdoors.
Direct drive fans have motor bearings only and on motors typically 7 and a half horsepower and larger those motor bearings are regreaseable so direct drive fans should be designed for acceptable bearing life and.
You have a fan a motor and maybe a coupling.
Unlike belt driven fans there s less energy loss because there s a reduced amount of friction as the fan operates.
Belt drive whole house fans that use an integrated pulley system take longer to install but a belt drive unit provides for a smoother and quieter operation.
Most whole house fans are relatively easy to install.
Direct drive fans have no power transmission loss since the propeller is directly connected to the motor shaft.
I had a belt drive with a two speed motor years ago.
The second pulley is connected to a shaft that drives the fan propeller.
A belt driven fan adds two extra bearings to the system.
Direct drive fans require fewer parts and thus usually less maintenance.
However a belt drive fan has power transmission loss due to the friction between the belt and sheaves and due to the drive shaft bearings.
That pulls more air with less fan noise.
The motors have two bearings whether the fan is direct drive or belt drive.
I think that the belt drive blades can turn slower with a deeper pitch than a direct drive.
Where on a belt drive fan the fan motor shaft has a pulley connected by a belt to a second pulley.
Direct drive tables also will give you a speed control so as a dj if you want to change the tempo to blend one song into another with two turntables it is pretty easy to do so with the range of speed adjustment available on a direct drive table.