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Exhaust Fan Use Cases: Direct Drive vs. Belt Drive

When selecting an exhaust fan for a commercial kitchen ventilation system, one of the key factors is choosing the correct drive style. Exhaust fans use a motor with either a belt drive or a direct drive. Belt drive fans use a belt that connects the motor and the fan impeller, and the belt is adjusted in order to achieve the desired fan speed. In a direct drive fan, the motor and the impeller are directly connected. Direct drive fans can be outfitted with an electronically commutated motor (ECM) which allows for fan speed adjustment for balancing as well as variable speed for fluctuating cooking levels. Selecting the correct fan style is crucial to meeting the airflow needs of the space and avoiding balancing or flexibility issues.

When to Use a Direct Drive Fan with ECM

For most commercial kitchens, a direct drive exhaust fan with an electronically commutated motor (ECM) is an ideal solution, particularly when ventilation flexibility is needed. While factors are weighed carefully to determine the appropriate exhaust fan model for a commercial kitchen, cooking loads are likely to vary in the final restaurant kitchen design. Therefore, it is beneficial to have a fan that can readily increase or decrease exhaust with the turn of a dial or the push of a button. Another application for an ECM is when a demand controlled ventilation system (DCKV) is implemented to automatically adjust fan speed in response to changes in the cooking load. This turndown capability makes direct drive fans a flexible option to service a variety of kitchen needs and cooking loads. The ability to modulate fan speed allows for energy savings up to 88% on systems paired with make-up air that can turn down 50%. Direct drive exhaust fans with ECM also last longer than belt drive fans and require less maintenance because they don’t have belts, bearings or pulleys that need to be serviced and replaced. However, using a direct drive exhaust fan with an ECM is most economical when moving less than 6,400 cfm. 

When to Use a Belt Drive Fan

When a large fan or a high airflow fan is needed that a direct drive motor cannot accommodate, a traditional exhaust fan with a belt drive motor is the appropriate choice. In instances where the airflow exceeds 6,400 cfm, it is more economical to use an exhaust fan with a belt drive motor. While certain speed and power requirements would render the exhaust fan too large for a direct drive motor to accommodate, a belt drive fan can achieve the necessary power to exhaust more effluent. Belt drive fans are ideal for situations where there is only one exhaust fan to supply multiple hoods. 

Overall, a direct drive exhaust fan with ECM will provide better value, more flexibility and less maintenance across its lifespan. For more detail on the different specifications for exhaust fans available from Accurex, download the product catalog. Our team of ventilation experts is always prepared to answer questions and assist you in selecting the correct exhaust fan for your commercial kitchen ventilation system. Find your local Accurex expert to receive personalized support and solutions.

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