When to Replace: Ventilation Systems

Components of commercial kitchen ventilation equipment include hoods, fire systems, pollution control units, grease extraction devices, controls, exhaust and make-up air systems.

Ventilation Systems: An Overview

Kitchen ventilation equipment removes heat and effluent generated during cooking of food. This engineered system includes stainless steel exhaust hoods, exhaust fans, make-up air units, grease removal apparatuses, fire suppression systems and controls.

Type I ventilation systems are grease rated for positioning over grease-producing appliances, while Type II units, or vapor hoods, remove heat and steam that dishwashers and some ovens generate. Ventilation systems must be in compliance with NFDA 96, a code that provides preventive and operative fire safety requirements intended to reduce the potential fire hazard of both public and private commercial cooking operations.

UL 710 requirements cover Type I commercial kitchen exhaust hoods that foodservice operators will install over commercial cooking equipment. The standard evaluates these hoods relative to minimum exhaust air flow required and maximum supply air flow allowed for capture and containment of cooking effluents under laboratory conditions. These codes, in addition to NFPA 70, the International Mechanical Code (IMC) and the Uniform Mechanical Code (UMC), cover products rated 600 volts or less.

“As foodservice equipment has changed, so have the ventilation system requirements,” says William Bender, founder and principal of William H. Bender & Associates, a Santa Clara, Calif.-based consultancy. “Combi ovens don’t require a gap between other pieces of equipment, which can reduce ventilation needs 2 to 4 feet. This is a cost saver.”

How to Know When to Replace Ventilation Systems

Depending on use, ventilation systems have an average lifespan of between 15 and 20 years. Here are five signs it might be time to replace a ventilation system.

Grease buildup: Heavy grease buildup on the ventilation system that an operator can’t remove using professional cleaning and maintenance services will compromise the safety and effectiveness of the unit.

Excessive airflows: If excessive airflows begin to increase HVAC costs due to an outdated ventilation system design, it may be time to consider replacing the existing equipment.

Menu changes: When new menu items require significant shifts in production, such as increased volume or equipment modifications, assess the ventilation system to ensure it is sized appropriately and can handle these changes.

Kitchen remodel: A back-of-the-house renovation typically requires a reassessment of the ventilation requirements, which most likely will result in modifications and/or replacement of the old unit.

Reliability Issues:  Unreliable equipment that requires frequent servicing and/or that is causing loss of sales due to downtime should be retired.

Ventilation Systems Applications

Ventilation systems are professionally sized and installed over cooking and warewashing equipment. Here’s a closer look at the role these systems play in commercial kitchens.

Foodservice operators use ventilation systems over the cookline and in the dishwashing area to remove heat and effluent.

“The design of the ventilation system is dependent on how the kitchen space is utilized and how equipment is arranged,” Bender says. “In placing these units, it’s important to consider the balance of air, placement of vents and ensure there is not too much air blowing on prepared food.”

The hoods include grease filtration capabilities to extract particles from the airstream.

These units also remove cooking odors from the kitchen by discharging the aromas outside of the building.

Maintaining Ventilation Systems

Ventilation system maintenance depends on the type and volume of cooking as well as federal, state and local codes. Here are eight maintenance tips to help extend the service life of a ventilation system. 

  • Professionally clean the hood and duct twice a year.
  • Clean the grease filters and the capture area at least weekly, depending on the application.
  • Less efficient grease extractors will need cleaning more often.
  • Thoroughly clean the makeup air unit’s aluminum mesh filters every six months.
  • Replace disposable makeup air filters monthly.
  • Clean the exhaust fan and inspect the belt biannually.
  • Depending on local code requirements and the operation, inspect fire suppression systems at least twice a year.
  • “Operators should look at the menu and the amount of manual cleaning that will be necessary to determine if a self-cleaning hood is a viable investment,” Bender says. “In most cases, these hoods pay for themselves over the lifetime of use.”

Spec Check: Ventilation Systems

Most ventilation issues arise from improper space balance with makeup air.

Here are four considerations operators should take into account when specifying a ventilation system.

Application: These systems are custom designed based on the type of foodservice facility, menu, equipment and volume. Federal and local codes also play a key role in the design and specification.  “The type and size of the hood is dependent on the amount of proteins prepared on the grill and fryer that produce heavy grease,” Bender says. “This has to do with vapors and the type of carbon or smoke being discharged.”

Goals: Consider what the operation hopes to achieve, such as cost, energy efficiency, aesthetics or a combination of all three.

Makeup air: In addition to the exhaust rate, operators should consider how makeup air will need to be brought in and in what capacity. Too much or too little air can cause the ventilation system to not draw properly. It’s key to have a comfort strategy in mind when considering the type of unit that is best suited for the operation.

Future changes: Not planning for future changes can be costly over the long term. When specifying a ventilation system, current and future needs for fire suppression, airflow and utilities should be taken into account.

Energy Efficiency and Ventilation Systems

Kitchen ventilation is not covered by the Energy Star program, but there are steps operators can take to increase the energy efficiency of these units.

When unbalanced or poorly designed, kitchen exhaust systems can allow heat and smoke to spill into the kitchen, negatively affecting air quality, back of house temperatures and utility bills.

“A balanced HVAC system works at a higher, more economical level when less ambient heat is being thrown up by kitchen equipment,” Bender says.

To increase energy efficiency, hood side panels can be added to capture and contain heat and smoke. Also, exhaust hoods should be turned off when the facility is closed.

There are several types of variable control ventilation systems that fluctuate the exhaust volume depending on the cooking activity and ventilation needs. This reduces the system’s operation to the minimum level necessary, which saves energy. Exhaust system costs can be reduced from 30 percent to 50 percent with these units, which can be installed on either new or existing equipment.

Improving Commercial Kitchen Ventilation System Performance” is a two-part kitchen ventilation design guide developed by the Food Service Technology Center that provides information to help operators achieve optimum performance and energy efficiency with commercial kitchen ventilation systems.

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