Dairy facilities have unique environmental and ventilation requirements with their need for adequate air quality while fighting harsh external environments. Proper airflow and cooling are essential for maintaining the welfare and productivity of animals. When selecting the right fan system for your operation, it's crucial to consider specific factors to determine which product is going to work best for your facility: belt drive fans or direct drive fans.

To get insight into which product might be ideal for any given operation, we caught up with VES-Artex's Technical Product Owner of Ventilation, Katlyn Langmeier. As someone who has a vast knowledge of ventilation systems specific to dairy production, including a Professional Engineer (PE) license, she says, "Direct drive fans are reliable long term when looking at output compared to belt drive fans. Belts stretch overtime, which causes a reduction in fan performance. Ventilation systems today are designed specifically to move a calculated amount of air to keep cows comfortable in their environment, so one would expect their fans to continually run at their rated airflow output, which isn’t always the case with belt drive fans. As the fans continue to run and the belts stretch, the fan airflow output will decrease resulting in an underventilated facility. Another reason for the dairy industry moving in the direction of direct drive fans in my opinion is due to the labor shortage. Producers are trying to run their operations and keep up with day to day tasks. Having to change belts on multiple fans does take up precious time, so that time can now be allocated to other tasks.”

What are the Pros of a Belt Drive Fan?

Initial Cost and Installation: Belt drive fans are a cost-effective choice during the initial purchase and installation stages, making them an attractive option for projects where budget considerations are heavy. Their affordability is particularly advantageous for budget-conscious projects, as the initial acquisition costs are typically lower compared to direct drive fans. This can translate to significant savings, allowing producers to allocate resources elsewhere in their facilities up front.

What are the Cons of a Belt Drive Fan?

Maintenance Requirements: While both types require overall maintenance such as cleaning the accumulated dirt and dust off, belt drive fans should have the belts replaced annually. Some producers look at this as a pro because they know their fans are getting attention at least once a year, but this regular maintenance should already be done on any fan and not forced due to belt changes. If regular maintenance is not routinely done, fan performance will be severely impacted. In addition, the overall cost of belts and sheaves can increase maintenance costs in the long run if not properly maintained. 

Noise Levels: Belt drive fans can generate more noise compared to direct drive fans, mostly from blade chop and electrical noise. Belt drive fans can also squeal on startup and squawk or chirp from worn or misaligned belts.

Vibration Concerns: Belt drive systems can introduce vibrations due to belt movement and potential misalignment issues. These vibrations can transmit to the fan structure and surrounding components, so proper alignment and tensioning are critical to minimizing vibrations. While some belt drive fans also have flexible couplings that can reduce vibration transmission, chain-mounted fans do not have reduced vibration capability, as it is transferred to the building differently.

What are the Pros of a Direct Drive Fan?

Lower Maintenance: In environments with dust, dirt, or chemicals, both systems require a similar maintenance schedule as dirt build-up will continue to create performance issues. The difference is that if it is not maintained, a belt drive system will fail faster and lose output performance compared to direct drive. In addition, a direct drive system won’t have belts, sheaves, or tensioners to replace, which lowers maintenance applications as well.

Noise Considerations: Direct-drive fans are generally quieter than belt-drive fans because there is no belt slippage or noise from the belt-drive components. Since there are no belts and sheaves, there is less potential for noise generated by the belt-to-sheave interaction. 

Vibration Concerns: Direct drive fans may have fewer vibration concerns because there are fewer moving parts, reducing the potential vibration sources. However, vibrations can still be generated if the fan is unbalanced or the motor needs to be more well-maintained.

What are the Cons of a Direct Drive Fan?

Cost and Budget Constraints: Direct drive fans may potentially pose budgetary constraints for some facilities as they may be more expensive when similar direct drive and belt driven fans are compared side-by-side. The elevated upfront costs associated with acquiring and installing direct drive fans may present challenges, particularly for smaller or budget-conscious operations. In such cases, careful consideration and financial planning are essential to ensure that the initial expense aligns with the facility's financial resources and long-term objectives.

While there may seem to be a clear winner in terms of which fan type is best for any given facility, there are pros and cons to both direct drive and belt drive fans. It's sometimes a complex decision when determining which ventilation system to adopt in your dairy facility. Still, here at VES-Artex, we strive to help our producers make the best decisions based on their specific needs. Contact your local dealer to discuss the best system for your barn with your short-term and long-term needs in mind.