Kitchen Makeup Air Units (MUA)

The Balance of Your Kitchen's Ecosystem

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Comprehensive Kitchen Makeup Air Units (MUA) Solutions

A Makeup Air Unit (MUA) is the essential counterpart to your kitchen exhaust system. For every cubic foot of air your exhaust hood pulls out of the building, the MUA must 'make up' that volume by pulling in fresh, filtered outside air. Without a properly functioning MUA, your kitchen becomes a vacuum, leading to a 'negative pressure' environment that wreaks havoc on your building's climate and your staff's comfort.

The High Stakes of Unbalanced Air

'Hard-to-Open' Doors

Negative pressure makes exterior doors difficult to open for guests or causes them to 'slam' shut, creating a safety hazard and a poor first impression.

Whistling and Drafts

Air will try to enter the building through any small gap—under doors, through windows, or even down plumbing vents—creating annoying whistling sounds and cold drafts.

Back-Drafting Hazards

A strong vacuum can actually pull dangerous carbon monoxide fumes back down the flues of your water heaters and ovens, creating a serious health risk.

HVAC Strain

Without makeup air, your dining room air conditioning system has to work significantly harder to overcome the vacuum, leading to skyrocketing energy bills and premature equipment failure.

⚠️ The Cost of Inaction

"You call us when the kitchen is unbearably hot or the front door won't stay closed. At this point, your staff is already frustrated and your AC system may be overstressed."

✅ The Professional Choice

"As your Reliable Partner, we perform regular MUA inspections. We clean or replace intake filters (which clog quickly in LA's environment), check fan belts, and verify that the heating or cooling elements within the MUA are firing correctly. We ensure your 'Air Exchange' ratio is perfect."

Why Choose Kitchen Services?

Digital Air-Flow Reports

We use specialized tools to measure air pressure and volume. You'll receive a report with photos of the unit's internals showing that your kitchen is perfectly balanced.

Kitchen Flow Respect

Make Up Air service usually happens on the roof or in the mechanical mezzanine. Our technicians work discreetly and quietly, ensuring your 'flow' remains uninterrupted while we optimize yours.

Honest Infrastructure Guidance

If your kitchen has added more cooking equipment but didn't upgrade the MUA, your system is likely out of balance. We provide a transparent 'Health Score' for your ventilation and help you plan for a system that matches your current output, supporting your decision 100%.

Need Emergency Service?

Our technicians are on call to minimize downtime and save your inventory.

Call us anytime

(323) 310-2010

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Digital Transparency

We provide detailed photo reports with every service call. You see exactly what we fixed.

Frequently Asked Questions

It is a mechanical fan system that pulls in fresh outdoor air to replace the air being removed by your kitchen's exhaust hoods. Its primary job is to maintain balanced air pressure within the building.

Yes. Per the International Mechanical Code (IMC), any exhaust system capable of pulling more than 400 CFM (Cubic Feet per Minute) must be provided with a make-up air system roughly equal to the exhaust rate.

Your building will develop negative air pressure. This creates a vacuum effect that makes doors hard to open, causes 'whistling' noises at windows, and forces the exhaust fan to work harder, significantly reducing its efficiency.

Negative pressure can cause back-drafting. It pulls dangerous combustion byproducts (like Carbon Monoxide) back down chimneys and water heater vents instead of allowing them to escape, posing a severe health risk to staff and customers.

The general industry standard is the 80/20 Rule: Roughly 80% of the replacement air should come from the MUA unit, while the remaining 20% can be 'transfer air' pulled from the dining area's HVAC system.

New 2026 standards emphasize Demand-Controlled Ventilation (DCV). If your total exhaust exceeds a certain threshold (often 5,000 CFM), your MUA must have variable-speed controls that modulate based on the actual cooking load.

While untempered units are cheaper, 2026 codes in many regions require make-up air to be tempered (heated to at least 60°F or cooled) to prevent dangerous drafts and to protect the main HVAC system from being overloaded.

This is the most common type for cold climates. It burns natural gas directly in the airstream (with 100% efficiency) to heat the incoming winter air before it enters the kitchen.

Yes. In dry climates, evaporative (swamp) cooling is a highly energy-efficient way to provide tempered make-up air during the summer without the high cost of mechanical refrigeration.

Codes require the MUA unit to be electrically interlocked with the exhaust fan. When the hood is turned on, the MUA must start automatically to ensure the air pressure remains balanced.

Typically on the roof or a concrete slab outside. It must be located at least 10 feet away from any exhaust fans or plumbing vents to prevent 're-entrainment' (sucking the dirty air back in).

Perforated Supply Plenums: Air comes out of the front of the hood. Ceiling Diffusers: Air is dropped from vents in the ceiling. Backwall Supply: Air is pushed up from behind the cooking line.

This is a common design flaw. If the MUA vent is too close to a thermostat, it will 'trick' the main HVAC system into thinking the room is much hotter or colder than it actually is.

Energy codes often limit 'internal' make-up air (air pumped directly into the hood cavity) to 10% of the total exhaust flow, as too much internal air can disrupt the hood's ability to capture smoke.

Only for very small operations (under 400 CFM). For commercial kitchens, relying on an open door is unreliable, unconditioned, and invites pests and dust into the prep area.

Because they pull in raw outdoor air, filters should be checked monthly and replaced every 3 months. Clogged filters are the #1 cause of 'weak' exhaust performance.

This usually means the pilot light is out or the gas burner has failed. Most units have a 'low-limit' safety switch that will shut the fan off if the air temperature is too low to prevent freezing the kitchen pipes.

This indicates your MUA intake is too close to your exhaust fan discharge. The MUA is sucking in the grease-laden air you just exhausted, which is a fire hazard and ruins the MUA filters.

A well-maintained commercial MUA unit typically lasts 15 to 20 years. The fan belts and motors are the most common parts that require replacement during that time.

Checking the fan belt. A loose or broken belt on the MUA unit will cause the kitchen to immediately go into a high negative-pressure state, making it feel stuffy and causing odors to drift into the dining room.