While both are equally Good power transmission mechanisms, there are some Gross differences, and paying attention to detail would give you the best out of the transmission system. Direct Drives and Belt driven Mechanisms are used in everyday objects right from A bicycle, Motorbikes, Cars, DJ turntables, Washing Machines, and many others. Both Belt Driven and Direct driven mechanisms have many sub-types in them which are used depending on the nature of the end-user. What we are aiming to do is give you some differences between the fans we use in our HVAC Systems in this post

9 Ways how Direct Driven Fans are different from its Belt-Driven relative

Direct driven fans have been becoming increasingly more popular in recent times compared to belt-driven blowers but both have their respective advantages and limitations which should be considered and that will help determine your choice.

Construction-wise, direct-driven fans have the blower and motor mounted on a common shaft whereas, in belt-driven fans, the blower and motor are mounted independently and coupled through a drive.

Break Down of a Belt Driven Blower
  • Efficiency: Belt driven < Direct driven ( 0-1)

Direct driven blowers have slightly better efficiency as compared to belt driven. Belt driven fans undergo power transmission losses due to the use of drives such as belts and pulleys whereas direct driven fans have the blower and motor rotate on a common single shaft thereby omitting the drive arrangement. 

  • Flexibility: Belt driven > Direct driven (1-1)

Belt driven fans are more flexible with speeds as the desired air discharge can simply be achieved by changing of pulleys. Direct driven fans will have to involve a VFD to achieve these variations.

  • Maintenance: Belt driven < Direct driven (1-2)

Frequency of maintenance required for direct driven fans is less due to the absence of drives & bearings. Belt driven fans on the other hand are more prone to wear & tear due to the use of belts, pulleys and bearings and require regular maintenance.

  • Sound: Belt driven > Direct driven ( 2-2)

For the same air discharge, belt driven blowers are slightly less noisy compared to direct driven blowers (measured from a distance of 3 meters).

  • Flameproof: Belt driven < Direct driven (2-3 )

Direct driven fans are the usual choice for flameproof applications because of the absence of bearings & provision of a copper ring between the impeller and inlet cone to avoid sparks. Belt driven fans have bearings on both the inlets and hence not recommended where fire hazard is a concern.

  • Replacement: Belt driven > Direct driven (3-3 )

The blower and motor in belt driven fans are mounted independently and replacing either can be done easily. In case of direct driven fans, the blower-motor arrangement will have to be dismantled first and replacing either and balancing them again requires high expertise.

  • Compactness: Belt driven < Direct driven (3-4)

Direct driven fans have compact designs and hence occupy less space within an Air Handling unit in comparison to belt driven fans.   

  • Cost:Advantage: Belt driven > Direct driven ( 4-4)

For the same air discharge, belt driven fans are cheaper compared to direct driven. They have two inlets unlike direct driven that has one so the selection for direct driven is usually a model higher. Also, most cases direct driven fans run with a VFD thereby boosting the price more.

  • Energy Efficiency: Belt driven < Direct driven ( 4-5 )

Direct driven fans have better compatibility with VFDs and consume less power compared to belt driven fans coupled with VFDs.

Washin Machine

That was really a close game between Belt Driven 4 points and Direct Driven 5 points. While both have its merits , we would prefer to use the direct driven type , unless our customers insist.

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