Problems frequently encountered in “Commercial Kitchen System”

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This question is great— It is a problem that is often encountered in “Commercial Kitchen System”
Many places install hoods to suck in air only but do not design for Fresh Air or

Makeup Air comes in to compensate for the air that is sucked out.The consequences include pressure and temperature.

and efficiency of the system 👇

🔥 1. Pressure in the kitchen “Excessive Negative Pressure”

When the Hood sucks out air without adding new air.
→ The pressure inside the kitchen is much lower than the surrounding area.
Effect:
 • Difficulty opening the kitchen door. (The suction door is tight)
 • Hot air or odors from the kitchen. “Leaks into other areas” such as the dining room
 • Air from the air vents in other rooms flows back into the kitchen.

🌫️ 2. Hood does not suck well - efficiency decreases.

The exhaust system will work well only if there is a balanced amount of air flowing into the kitchen.
But if there is no Fresh Air → the air flow under the Hood will be “incomplete”.
Effect:
 • Smoke escapes from the Hood.
 • The temperature in the kitchen is very high.
 • Smell and hot steam drift out of the room.

⚡ 3. Exhaust fan works too hard (Overload)

Because the air inside the kitchen has low pressure.
→ The fan must spin faster to try and suck out the air.
The result is:
 • Motor is hot.
 • Loud noise
 • Shorter lifespan.

💨 4. The air circulation in the building is out of balance.

If the kitchen does not have Makeup Air → Air from other zones (restaurant, lobby) will be sucked into the kitchen instead.
The result is:
 • Other zones are getting hotter. because the air is sucked out
 • Integrated air conditioning system (AHU/FCU) works hard.
 • The pressure of the entire building is out of balance (Air balance broken).

💧 5. High humidity and condensation problems. (Condensation)

When the hot and humid air from cooking is not completely sucked out
There will be “water buildup” on the ceiling, walls, or cold air ducts → Risk of mold and grease accumulation.

✅ Correct design guidelines
 1. Air filling rate (Makeup Air) ≈ 80–90% of the air that the Hood sucks out.
 • The rest (10–20%) should be kept as Negative Pressure to prevent odor leakage.
 2. Fill air temperature: Should be cooler (about 26–30°C) to help reduce kitchen temperature.
 3. Air supply position: In front of or around the Hood to "support" the air into the Hood in a directional manner.
 4. Install Damper / Grill / Diffuser specifically designed for Kitchen Makeup Air.