Direct drive fans have no power transmission loss since the propeller is directly connected to the motor shaft.
Attic fan belt vs direct drive.
You have a fan a motor and maybe a coupling.
Coming to the advantage of this kind of an industrial fan the biggest advantage is greater efficiency.
Where on a belt drive fan the fan motor shaft has a pulley connected by a belt to a second pulley.
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.
It s incredibly hard to balance a belt and pulley system.
There s also no belt residue and these fans cost less to maintain generally speaking because belts don t wear down and break.
Unlike the belt driven fans in case of a direct drive fan there is lesser energy loss.
It s balance or lack of balance actually which causes most of the noise.
Greater efficiency is the biggest pro of direct drive fan configurations.
Sizing a whole house fan.
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.
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.
Installation of an air vent attic fan in my garage.
The second pulley is connected to a shaft that drives the fan propeller.
This ventamatic whole house direct drive fan offers an efficient way to trim cooling costs while keeping your entire home more comfortable.
Direct drive models are the most do it yourself friendly because for most no attic joists need to be cut.
Ventamatic whole house fan 24in 3092 cfm belt drive model cx24bd2spd 9.
That would be quiet but would look like a mess from outdoors.
Most whole house fans are relatively easy to install.
Unlike belt driven fans there s less energy loss because there s a reduced amount of friction as the fan operates.
Cool attic belt drive whole house fan 36in 9 700 cfm model cx36bd2spd.
Belt drive fans are quieter than direct but still noisy.
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.