Most of the five basic parts of an exhaust fan are quickly identifiable: bowl, base, blades, motor, and curb. But it’s easy to get confused between the exhaust fan base and curb as well as the roles they play in your commercial kitchen ventilation system. Here’s a quick primer on telling the two apart as well as their purposes.
What is an exhaust fan base?
The exhaust fan base is the very bottom portion of the exhaust fan and is usually constructed of heavy-duty galvanized steel to withstand the demanding and harsh environment of an exposed rooftop. Welded corners provide extra strength and rigidity to the fan unit and provides added support to exhaust fan hinges. Exhaust fan hinges are required to be installed on any fan that exhausts grease or smoke. The hinge serves as a movable joint between the exhaust fan base and the curb. It allows the fan to be easily opened, closed, or secured in a locked position. This makes inspection, cleaning and maintenance of the fan much safer and easier.
What is an exhaust fan roof curb?
A curb is basically a metal box for the exhaust fan to sit on. It may look simple, but it plays a very important role in your ventilation system. Curbs are generally used only for rooftop exhaust fan installations, and while some wall mounted fans may use a curb, they usually only require the use of a mounting bracket. Roof curbs should be between 1.5″ and 1.75″ smaller than base of your exhaust fan base. The curb sits between the roof and the fan base and is designed to provide a watertight, weatherproof connection that will protect the interior of your ventilation system. Roof curbs can be prefabricated or factory built and should always be installed by an experienced contractor.
Exhaust fan grease box.
There are some accessories that may be attached to your roof curb either before or after installation of your fan is complete. If your ventilation system requires a backdraft damper, it will typically be secured within the curb to the bottom of a damper box or damper support flanges before the fan is placed on top. Backdraft dampers are used to help the overall function of the ventilation system by preventing reverse airflow which can lead to too much negative pressure in the kitchen. This buildup of negative pressure can cause a lot of different problems from just annoying to downright dangerous.
Another accessory that is commonly attached to a roof curb is a grease box or other rooftop grease containment system. It is important to collect any fats, oils, or grease that are emitted from your exhaust fan to keep them off of your rooftop. Allowing these to run off onto your roof can cause roof leaks and structural damage as well as become dangerous fire hazards. And when rainwater carries the pollutants off of the roof and into the storm water system, you could contaminate the water supply and also end up paying costly EPA storm water violation fines.
Learn more about roof mounted exhaust fan curbs in this short video:
If you’re looking for a new exhaust fan, let the experts at HoodFilters.com help. We guarantee the lowest price, offer fast and free shipping, and of course, our unbeatable customer service! Visit us online and check out our Hood and Fan Assistant to determine the right set-up for your commercial kitchen, or just give us a call at 877-394-9731. You can also send your questions in an email to customerservice@hoodfilters.com.
