Need to learn more about the exhaust fan for a kitchen exhaust system: types, code enforcement, and continued service? You have found yourself in the right spot. This blog post will dive deep into what you need to know.
KITCHEN EXHAUST SYSTEM – The Exhaust Fan
The exhaust fan is located outside on the roof of each restaurant. The fan is the device that pulls all the air and grease vapor through the KITCHEN EXHAUST SYSTEM.
There are several styles of fans that can be used for operating a KITCHEN EXHAUST SYSTEM, the typical models being:
- Utility-set Fan
- Up-blast Exhaust Fan
- Down-Blast Exhaust Fan – NOT KITCHEN EXHAUST SYSTEM
- Supreme Exhaust Fan
- Pollution Control Unit (PCU)
- In Line Exhaust Fan
Utility-Set Exhaust Fan
A Utility-set exhaust fan has the ductwork turn into the exhaust fan blades, with the motor housing outside in its own housing. These exhaust fans are used with cooklines that produce a large amount of heat as well as large volume of air.
Figure 33 is an example of a utility set exhaust fan for a burger restaurant.
Up-Blast Exhaust Fan
These are the most common exhaust fan you will encounter when servicing the KITCHEN EXHAUST SYSTEM.
Upblast exhaust fans are produced in many sizes to meet each KITCHEN EXHAUST SYSTEM’s air flow requirements. The more air flow needed to evacuate the exhaust, the larger the fan.
Figure 34, is a Captive Aire Up-blast exhaust fan, located on the roof top of a breakfast restaurant in Meridian, ID. This is a nice and shiny new fan. Not all up-blast fans are this new and shiny, but they all are designed the same.
Figure 35 shows and old upblast exhaust fan being used on the KITCHEN EXHAUST SYSTEM of a breakfast restaurant. Same basic design with variations in construction.
- The fan motor housing is in the center of the fan.
- The fan blades are located directly below the motor.
- The air is then directed up and out, around the entire center housing.
This design allows access for cleaning from above the blades and below the blades when the exhaust fan is tipped backwards.
Down-Blast Exhaust Fan
Seen here, Figure 36, is a Down-blast exhaust fan. This type of fan is typically used for ambient air exhaust, meaning that it is NOT connected to the kitchen exhaust system.
This exhaust fan would push the greasy air straight onto the roof surface and create grease buildup on the roof. Manufacturers are looking to avoid grease buildup and want the air to be exhausted up and away from the building.
Supreme Exhaust Fan
Below, Figure 37, are the three stages of a supreme exhaust fans. These are large exhaust fan that are designed with a hinge on the fan wheel and the base. This allow the wheel to be pivoted out of the housing, allowing easy cleaning access.
PRO TIP – Supreme Exhaust Fan
These tipping features make the Supreme exhaust fan easy to clean, however, due to their unique design these fans are also expensive and therefore infrequently used. Most Jack-in-the-box restaurant concepts have these type of exhaust fans (Figure 38).
Pollution Control Unit (PCU)
Pollution Control Units are designed conjunction with the exhaust fan. They are an effort to capture more particulates of grease in addition odor from the cooking operations.
These systems are used when mandated due city code compliance or the proximity of the commercial cooking exhaust system’s possible interference with surrounding tenants, bystanders, or pollution control adherence (cooking odor too strong on a main walkway).
To accomplish pollution control, the fan pulls all exhaust air through a series of filters, Figure 39:
- Paper filters: used to remove grease more effectively
- Electrostatic filters: more complete grease and smoke removal
- Carbon filters: used to removed odor
In-Line Exhaust Fan
In-Line Exhaust Fans are used when you have ductwork after the exhaust fan (Figure 40):
- Duct — Fan — Duct — Outlet Vent
In-Line fans are uncommon but can be found when the placement of the fan of the rooftop or vent is difficult to achieve in the building. Also, these systems are typically difficult to clean due to the advanced level of prep necessary to clean the system properly.
There are specific NPFA 96 codes that regulate In-Line Fans. These codes specify a low point drain and access doors on each side of the fan to allow adequate access for service.
Exhaust Fan – NFPA 96 Codes
Up-blast exhaust fans are required to be hinged. As seen in the picture below, Figure 41, the exhaust fan can be safely removed from the roof-jack with the assistance of a hinge kit.
8.1.2.1 – Upblast fans with motors surrounded by the airstream shall be hinged and supplied with flexible weatherproof electrical cable and service hold-open retainers.
