Commercial kitchen's exhaust contaminates cooking air. When you remove large quantities of air required for kitchen exhaust you need to safely bring an equal amount of air back into the building, typically directly to the kitchen, to "make-up" the air you are exhausting while cooking. The "type" of air you bring back in depends on comfort and cost demands. Let's explore three kitchen scenarios and the different types of make-up air units.

Scenario 1:

Concessions are made on comfort to keep costs low.

Common Make-Up Air units for these scenarios are either untempered or heat-only. An untempered unit brings air into your kitchen at the exact temperature and humidity as it is outside. This is a lower-cost option as the unit simply drives outdoor air into the kitchen. Two items to keep in mind with these units:

Supply Location

Bring air back into the kitchen as close to the hood as possible, by using a perforated supply plenum along the hood. This increases hood capture and minimizes untempered supply air from mixing with the rest of the building.

Air Quality

Ensure the unit has an effective filter to avoid bringing contaminants into your kitchen.

In cooler climates, a heat only unit is typically used which increases comfort and prevents unwanted cooling of food.

Scenario 2:

General Kitchen comfort is expected or desired.

In this case, you don't want freezing winter or hot summer air going directly on the chef or the space, for that matter. To prevent discomfort in the kitchen, select a make-up air unit with both heating and cooling. Cooling supply air comes at a cost, making it important to find a durable cooling unit that provides optimal performance and properly utilizes that cooling for the best overall value. There are a couple additional design factors to consider with cooled units:

Setpoints

Ensure the unit can begin cooling properly when the outdoor air temperature hits 75°F, rather than waiting until it gets as hot as 85°F (see chart below on unit utilization increase in different climates).

Unit Configuration

Confirm the unit is oriented where the cooling coil is before the fan, drawing air between the coils rather than blowing air through them. This utilization of the entire cooling coil results in consistent and effective cooling.

Scenario 3:

Comfort is paramount in the kitchen and/or open kitchens where patron comfort is dependent on make-up air tempering choices.

In these scenarios, make-up air is brought into a space that could mix with the air consumers are feeling. In these cases, heating and cooling become key, and humidity control may be considered. This can all be accomplished with a Dedicated Outdoor Air System (DOAS), which has the capability to fully condition outdoor air to a precise level as well as dehumidify the air. While this type of make-up air will have the highest first costs, it can actually save money and space by combining and/or eliminating the use of multiple HVAC units.

Rely on your local Accurex kitchen ventilation expert to review your design and help you determine the right unit for your concept. Visit Accurex Sales to find a local expert.