2018 IMC Reference
Commercial Kitchen Exhaust and Makeup Air
A practical guide for restaurants and food-service spaces: kitchen hood exhaust, makeup air, rooftop units, pressure balance, comfort complaints, odors, and HVAC coordination.
2018 International Mechanical Code
Mechanical code references used on this topic
The 2018 International Mechanical Code addresses commercial kitchen exhaust in Chapter 5. Sections 506, 507, 508, and 509 cover commercial kitchen exhaust ducts and equipment, hoods, makeup air, and fire-suppression system coordination.
Model code reference
References are based on the 2018 IMC, the mechanical code book used for Arizona HVAC contractor licensing study. Local adoption decides the enforceable version.
Manufacturer instructions
2018 IMC Section 304.1 ties equipment installation to approved equipment, listing, manufacturer instructions, and the code.
Local inspection
2018 IMC Chapter 1 covers administration, permits, inspections, and the code official role. Permitted work follows the local jurisdiction.
Restaurant HVAC Context
Kitchen exhaust affects pressure, heat, and cooling
A restaurant can have working AC equipment and still feel hot, drafty, smoky, or out of balance if the kitchen exhaust and makeup air are wrong. The hood may remove a large amount of air, and that air has to be replaced through a controlled makeup-air path.
Kitchen exhaust, grease ducts, hood systems, makeup air, fire-suppression coordination, clearances, rooftop equipment, and fan operation are specialized. CTS can evaluate the HVAC side and identify when a hood, fire-suppression, controls, or specialty contractor needs to be involved.
- Hood exhaust removes air that the building has to replace.
- Missing makeup air can pull hot outdoor air through doors and gaps.
- Kitchen pressure problems can affect dining comfort and rooftop unit performance.
- Rooftop access, fan condition, belts, filters, controls, and unit operation all matter.
- Specialty hood, grease duct, and fire-suppression work may need other licensed specialists.
Hood Exhaust
Kitchen hood exhaust
Kitchen hood exhaust removes heat, smoke, steam, grease-laden vapors, and odors from cooking equipment. That exhaust path may include hood filters, grease ducts, rooftop exhaust fans, controls, and fire-suppression coordination.
When a kitchen exhaust system is not working correctly, the symptom may be heat in the kitchen, smoke, odors, greasy air, fan noise, poor capture at the hood, or complaints from the dining room and neighboring spaces.
Makeup Air
Makeup air for hood exhaust
If a hood removes a large amount of air, the building has to replace it. Without a planned makeup-air path, the restaurant may pull air through front doors, ceiling cavities, gaps, restrooms, water heater rooms, or other unwanted paths.
That can make doors hard to open, bring hot Phoenix air into the space, move odors, affect comfort, and make the AC look weak even when the unit is not the only problem.
Pressure Balance
Restaurant pressure balance and comfort
A dining room that feels hot, drafty, smoky, or hard to balance may have an exhaust and makeup-air problem. If the building is too negative, the AC may fight constant hot-air infiltration. If makeup air is dumped poorly, staff and customers may feel hot or uncomfortable.
The diagnostic should look at what is running: hood exhaust, makeup-air unit, rooftop AC, thermostats, economizer or outside-air settings, filters, belts, controls, and whether the complaint happens only during cooking hours.
Rooftop Coordination
Rooftop equipment serving the space
Restaurants often have multiple rooftop units: AC package units, exhaust fans, makeup-air units, and sometimes refrigeration-related equipment. One failed belt, dirty filter, bad motor, stuck damper, or failed control can change how the space feels.
CTS checks the HVAC side: rooftop unit operation, filters, coils, motors, capacitors, contactors, disconnects, controls, thermostat calls, airflow, and whether the complaint points toward exhaust or makeup-air coordination.
Scope Boundaries
Kitchen exhaust scope and coordination
Kitchen hoods, grease ducts, fire suppression, fire alarms, hood cleaning, and some exhaust system changes can involve specialists beyond a normal AC repair. That should be identified early so the restaurant owner does not get half an answer.
CTS can help determine whether the call looks like rooftop HVAC repair, controls, maintenance, filter or belt issues, makeup-air concern, AC replacement planning, or a specialty hood/exhaust project.
Related CTS Pages
Related service pages
Related service pages connect the reference topic to diagnostics, repair planning, and replacement decisions.
Commercial HVAC
Commercial service for rooftop units, package units, tenant spaces, restaurants, controls, maintenance, and replacement planning.
Ventilation basics
Outdoor air, exhaust, makeup air, pressure balance, tenant spaces, and why ventilation is different from cooling airflow.
Rooftop access
Access, service clearance, rooftop units, disconnects, panels, and replacement planning for HVAC equipment.
AC maintenance
Maintenance can catch dirty filters, weak electrical parts, coil issues, fan problems, drain issues, and early cooling failures.
Commercial kitchen exhaust and makeup air FAQs
Answers about repair, replacement, maintenance, and service.
Why does kitchen exhaust affect the AC?
Kitchen exhaust removes air from the building. If that air is not replaced correctly, the building can pull hot outside air in and make the AC work harder.
What is makeup air in a restaurant?
Makeup air is replacement air brought into the building to replace the air removed by hood exhaust or other exhaust fans.
Can bad makeup air make a dining room uncomfortable?
Yes. Poor makeup-air balance can create drafts, hot areas, odors, door pressure, smoky areas, and AC performance complaints.
Does CTS handle every part of kitchen hood work?
CTS can help with the HVAC side, rooftop units, controls, maintenance, and comfort diagnostics. Hood, grease duct, and fire-suppression work may require specialty contractors.
What details should a restaurant provide when calling?
Mention the main complaint, whether the hood exhaust is running, whether makeup air is present, rooftop access, business hours, tenant approval, and whether the problem happens only during cooking.
Call CTS Air Conditioning
CTS handles AC repair, HVAC service, replacement, maintenance, water heaters, and other plumbing across the Phoenix area.
480-696-5033