How to Select the Right Roof Mounted Kitchen Exhaust Fan

Installing a high-quality roof mounted kitchen exhaust fan is one of the most important investments a commercial kitchen can make. Properly removing grease, smoke, and heat from your kitchen improves safety, protects your building, and provides a healthier work environment.

With so many exhaust fan options on the market, it can be tricky to select the right model for your specific needs.

Types of Roof Mounted Exhaust Fans

There are several main types of roof mounted exhaust fans designed for commercial kitchen applications:

Centrifugal Upblast Exhaust Fans

Centrifugal upblast models are the most common choice for commercial kitchen ventilation. They utilize a spinning impeller wheel to draw air up through the fan and vent it vertically through the roof.

• Provide high airflow capacities from 500 - 30,000+ CFM
• Designed for medium to high static pressure
• Typically belt-driven with higher horsepower motors
• Well-suited for kitchen hood or direct building exhaust

Axial Roof Upblast Exhaust Fans

Axial exhaust fans draw air through parallel to the fan blade axis and expel it vertically.

• Best for low-medium static pressure applications
• Provide airflow volumes from 3,000 - 26,000 CFM
• Offer quieter operation than centrifugal models
• Ideal for makeup air or kitchen ventilation needs

Propeller Roof Exhaust Fans

Sometimes called "blower" fans, propeller roof exhaust models feature fan blades that rotate to push air out.

• Designed for low static pressure applications
• Deliver airflows from 800 - 11,000 CFM
• Compact in size and usually lightweight
• Provide cost-effective performance for light-duty ventilation

Key Factors to Consider

Selecting the right commercial kitchen exhaust fan requires careful consideration of your facility's unique needs. Here are the most important factors to take into account:

Ventilation Requirements

First and foremost, the exhaust fan must meet your kitchen's airflow (CFM) requirements to effectively remove heat, smoke and grease. Consider the size of your kitchen, number of appliances/hoods, and peak operating conditions. Also account for future equipment upgrades that may increase demand. A qualified contractor can help calculate your exact CFM needs.

Static Pressure

Determine the static pressure in your ductwork system. Long or complex duct runs create higher resistance and static pressure. Choose an exhaust fan powerful enough to overcome that pressure and deliver sufficient airflow.

Noise Level

Commercial kitchen environments are often loud, but excess fan noise can make communication difficult. Compare noise ratings (dBA) to find a quieter fan or one that offers speed control to reduce sound as needed.

Venting Type

Decide if you need a fan capable of vertical- or horizontal-discharge via HVAC ductwork or one with a factory-built exhaust stack for direct building venting. Your chosen exhaust fan must align with your existing or planned duct/vent configuration.

Fan Controls

Many roof exhaust fans offer speed modulation via variable frequency drives (VFDs). This allows you to match the CFM output to current kitchen demand. VFDs also provide soft start/stop to extend motor life. Determine if advanced controls are beneficial.

Construction and Durability

Kitchen exhaust fans must withstand high temperatures, grease, and moisture. Look for robust housings, corrosion-resistant materials, sealed ball bearings, and baked-on powder coat finishes. Component quality greatly affects longevity.

Installation Requirements

Factor in unit weight/dimensions, ducting, electrical, and structural modifications needed. Heavier exhaust fans often require a pre-fabricated roof curb to properly distribute weight. If access is limited, a smaller fan size may be better.

Available Service and Support

Commercial kitchens rely heavily on ventilation, so quick service response time is crucial if issues arise. Opt for an exhaust fan brand that offers 24/7 technical support along with local service technicians and any needed replacement parts.

Budget

While initial cost is important, also consider lifetime value, energy efficiency, maintenance needs, and warranty terms. A higher-quality exhaust fan often provides greater long-term savings through reliable operation and consistent performance.

Installation Process for a Roof Mounted Exhaust Fan

Proper installation is key to maximize performance and avoid premature breakdowns. Here is an overview of the roof mounted exhaust fan installation process:

Select the Roof Location

Choose an area directly above your kitchen hood system or cooking equipment. Ensure adequate clearance from HVAC units, ductwork, and other rooftop structures. Check that the surface is structurally sound.

Install Roof Curb

Fabricated curbs provide a transition piece between the roof and fan. Set the curb in place and fasten securely to the roof deck. Ensure it is level, plumb, and properly flashed/sealed. Use any required vibration isolators.

Mount the Exhaust Fan

Carefully place the fan assembly onto the curb per the manufacturer's instructions. Apply a bead of silicone caulk between the curb and fan base. Insert and tighten all bolts to the specified torque.

Connect Ductwork

Attach ductwork to the exhaust fan outlet using zip screws or flanged connections. Seal all joints thoroughly. Flexible connectors can reduce vibration transmission. Support duct as needed.

Complete Wiring

Have a licensed electrician connect the power source to the exhaust fan according to the rating label. This often includes high-voltage and low-voltage wiring for controls.

Test for Proper Operation

Start up the fan to verify smooth operation across its full speed range. Check for excess vibration and unusual noise. Confirm adequate airflow by measuring CFM output with an anemometer.

Finish Roof Work

Complete all roofing work around the curb and fan. Install guy wires secured to the roof structure if required. Apply any special coatings to protect the fan from weather exposure.

Maintenance Tips for Optimal Performance

Regular maintenance keeps your roof mounted kitchen exhaust fan operating effectively for years. Follow these upkeep best practices:

• Clean fan wheel, housing, and grease drain pan regularly
• Inspect ductwork and vents for any blockages
• Check belt tension and realign if needed
• Lubricate motor bearings every 6-12 months
• Tighten any loose bolts/fasteners on the fan or curb
• Confirm electrical connections remain intact
• Repair any leaks found on fan housing or ductwork
• Replace filters or worn components per manufacturer guidelines

A yearly professional maintenance visit can catch any issues before they lead to breakdowns. Always turn off power at the breaker when servicing the exhaust fan.