Reasons Restaurants Need a Make Up Air Unit For the Kitchen

When you add a make-up air unit for your kitchen, it adds replacement air for what’s being drawn out of the kitchen by your exhaust hoods.

What is make up air? Simply stated, a make-up air unit pulls air in to your space from outdoors and conditions it to the indoor temperature, to replace air that’s pulled out by your kitchen exhaust equipment. Without it, you get back drafting, poor temperature control, negative air pressure and air quality problems. Poor ventilation can also contribute to the spread of disease.

Why is make up air important for restaurants?

1. To replace air removed by exhaust systems

Depending on the type of cooking you are doing, you might even have more than one exhaust system in your kitchen: one for heat & grease generating cooking appliances (like fryers, grills, and cooktops) and another for steam-generating appliances (such as dishwashing equipment and baking ovens).

Restaurant kitchen exhaust systems are often very powerful, removing thousands of cubic feet of air per minute. When air is removed from your kitchen, it needs to be replaced with fresh air. Without that replacement air, you wind up with all sorts of unpleasant and even dangerous conditions, which we’ll get to in a minute. The problem is compounded in newer buildings constructed to be air-tight, which prevents the natural flow of outside air into the space.

2. To prevent odours from sneaking out

If your HVAC is designed correctly, about 10 percent of the replacement air will move into your kitchen from adjacent areas like your dining room. That’s a good thing, since air moving in to your kitchen will help keep odours from migrating out. But you don’t want TOO much air moving into your kitchen from other areas, because that makes things drafty and causes other concerns.

The remaining 90 percent needs to be replaced, and that’s called “supply air.” It’s unlikely that your air conditioning system alone can replace that much exhausted air on its own. That’s why you need a make-up air unit for your kitchen, to add the needed supply air from outdoors. The make-up air unit for your kitchen will usually be installed on the roof (if available) or in a mechanical room, and provide a steady stream of outside supply air into your kitchen.

3. To provide healthy ventilation for your employees and customers

Without enough supply air entering your space, your air quality can suffer. Adequate ventilation and air exchange is important to prevent harbouring bacteria, mould, and viruses that can cause disease. According to the World Health Organization, “Poorly ventilated buildings affect air quality and can contribute to the spread of disease.”

So, how can you tell if your restaurant is not getting an adequate supply of replacement air? You’ll notice the following signs that you need a make-up air unit for your kitchen.

8 problems you can solve with a make-up air unit for your kitchen

1. Unpleasant Odours Where You Don't Want Them

Having a make-up air unit for your kitchen allows better control of airflow, to direct cooking odours away from where your customers are trying to enjoy a meal.

2. Negative Air Pressure.

The air balance problems that result from inadequate replacement air cause lots of annoying symptoms in your restaurant: drafts, doors that are hard to open, or doors that slam shut with no warning.

Those things happen in a negative air pressure system because air is finding its way in through windows, doors and any available crack and hole. You’ll notice high velocity cross drafts that can make your diners and your workers quite uncomfortable. Even worse, any dust being blown around can end up in your food! You might even hear distracting whines, whistles and rattles as uncontrolled drafts move around your space. All these things add up to a very unpleasant dining experience that could be driving your customers away.

3. Back Drafting

Your restaurant kitchen is designed with draft stacks or chimneys to vent dangerous carbon monoxide and other by-products from your heating systems and from cooking appliances like grilles and wood-fired ovens. In a negative air pressure situation caused by inadequate supply air, those drafts that are supposed to be escaping outside could be moving back into your space. That means everyone from your employees to your customers could be breathing in dangerous substances.

The next thing you know, your carbon monoxide detectors will be going off, which can result in a major disruption of business when the fire department shows up and evacuates the building.

4. HVAC Problems

When chimneys are not drafting properly, you can experience problems with heating systems, such as pilot lights extinguishing and damage to stacks and heat exchangers.

5. Poorly Perfoming Kitchen Exhaust Hoods

Without a make-up air unit for your kitchen, your exhaust hoods don’t do their job as well. That’s because the lack of supply air causes an increase in static pressure that lowers the cubic feet per minute (CFM) of air the equipment can remove from your kitchen.

6. Excess Kitchen Grease

When your exhaust doesn’t work well, you’ll notice more grease building up on the surfaces of your kitchen, and your staff will have to spend more time cleaning.

7. Air Quality Concerns

Can’t be taken lightly since they impact the health and safety of your employees. The smoke and VOCs given off by cooking appliances can cause air quality concerns in your kitchen. Exposure to these substances can lead to respiratory problems for the people who spend a lot of time in that kitchen. The last thing you need is your kitchen workers calling in sick!

8. Poor Comfort Conditions And Higher Energy Bills

When your restaurant is lacking replacement air, it leads to unbalanced heating and cooling conditions, and often the measures taken to mediate those problems can make matters worse. And increase your utility bills!

For example, when outside air is being pulled in through doors and windows, the exterior of your space can become too hot or too cold (depending on the outside conditions). Then what will you do? In the absence of a good HVAC designer, probably you will add more heaters or fans around the perimeter. But since the outside air keeps blowing in with more pressure, that heat or air won’t stay where you want it, and will just drive up your energy costs.