Commercial Kitchen Ventilation: Hood Exhaust, Make-Up Air & Pressure Balancing

Every cubic foot of air a kitchen hood pushes out of the building has to be replaced by a cubic foot coming in. When that replacement air is not planned, the building finds it on its own, through the front door, the drive-through window, the rooftop unit’s return, and the walk-in gasket. TechBridge Pacific HVAC Corp repairs, installs, and balances the mechanical side of commercial kitchen ventilation: exhaust fans, make-up air units, interlocks, and controls, for restaurants and commercial kitchens across Collin County and North Dallas. Commercial-only, based in Melissa, TX, license TDLR TACLA 00151786R.

Call (469) 609-6204 or request service online.

Signs Your Kitchen Ventilation Is Out of Balance

• The front door is hard to open, or slams shut on its own
• Smoke and cooking odors roll out from under the hood into the dining room
• Pilot lights and standing burners blow out; gas water heaters or furnaces backdraft
• Cold drafts at the host stand in winter, hot drafts in summer
• The dining room never reaches setpoint even though the rooftop units run constantly
• Grease accumulating on ceiling tiles and RTU return grilles
• Walk-in and reach-in units icing or running long because warm humid air is being pulled past their doors
• The make-up air unit runs but blows cold air on the cook line in winter, or does not run at all

Each of these is a symptom of negative pressure, and negative pressure is a mechanical problem with a mechanical fix.

What We Service

Exhaust fans

Upblast and utility-set exhaust fans on the roof: motor and bearing replacement, belt and pulley replacement, hinge kits and grease containment, VFD and speed controls, and airflow verification. A slipping belt on a hood exhaust fan quietly cuts capture velocity long before anyone notices the fan is “still running.”

Make-up air units

Direct-fired and indirect-fired gas make-up air units, and untempered supply fans. Repairs include burner and ignition faults, gas valve and pressure switch problems, flame safeguard and controller faults, damper actuators, intake filters, supply fan motors and belts, and discharge temperature controls. We install new MUAs sized to the hood exhaust volume and set discharge temperature so winter make-up air does not freeze the line cooks.

Hood interlocks and controls

Code requires the make-up air to run whenever the exhaust runs. We repair and install interlocks so the MUA starts and stops with the hood, integrate fire-suppression shutdown where required, and set up demand-control ventilation on hoods equipped for it. We work on CaptiveAire, Accurex, Greenheck, and similar systems.

Pressure balancing

Airflow measurement at the hood and the MUA, pressure differential readings between the kitchen, the dining room, and outdoors, and adjustment of fan speeds, dampers, and setpoints to bring the kitchen to a slight negative relative to the dining room and the dining room to a slight positive relative to outdoors. That is where a code-compliant, comfortable restaurant sits.

How We Diagnose a Ventilation Problem

• Measure exhaust airflow at each hood and compare it to the hood’s design CFM and the fan’s nameplate.
• Measure make-up air at the MUA discharge and any dedicated supply grilles.
• Read the pressure across the front door, the kitchen door, and the RTU return.
• Verify the interlock: does the MUA start with the hood? Does it stay running? Does the damper actually open?
• Check the MUA burner and controls: gas pressure, ignition sequence, discharge temperature, and safeties.
• Look at the RTUs and refrigeration as victims: are they running long because of negative pressure? See rooftop unit service and commercial refrigeration.

You get a written summary with the airflow and pressure numbers, the cause, and the fix, with pricing, before we proceed.

New Installations and Build-Outs

On a new restaurant or a kitchen remodel we size the make-up air to the hood exhaust volume (typically 80 to 90 percent of exhaust, with the RTUs supplying the rest, depending on the design), select tempered or untempered supply based on where the air is delivered, coordinate curb locations and roof penetrations with the hood contractor, and handle gas, electrical, and controls. We commission by measuring, not by assuming, and leave you the airflow and pressure readings for your inspection file.

Maintenance for Kitchen Ventilation

Exhaust fans and MUAs are included in our Large commercial plan and the MUA is included in the Medium plan. Quarterly, we check belts and pulleys, motor amp draw, bearings, hinge kits and grease containment, MUA filters, burner operation, damper actuators, and interlock function, and we log airflow so drift is caught before it becomes a complaint. Details on the maintenance agreements page. Grease-duct cleaning is performed by a hood-cleaning contractor; we coordinate with yours as needed.

Why TechBridge Pacific

Two technicians, commercial-only. We service the RTUs, the ventilation, and the refrigeration in the same building, which means we see how they affect each other instead of treating each one in isolation. EPA 608 certified, factory training from LG and Daikin (certifications). For the full restaurant picture see restaurant HVAC.

Service Area

McKinney, Allen, Melissa, Anna, Prosper, Celina, Frisco, Plano, Richardson, and Dallas.

Frequently Asked Questions

What is a make-up air unit and do I need one?

A make-up air unit supplies outdoor air to replace what the hood exhausts. If your kitchen has a Type I hood, the mechanical code requires make-up air, and in practice any hood over a few hundred CFM will put the building into negative pressure without it.

Why is my front door hard to open?

The building is in negative pressure: the hood is exhausting more air than is being supplied. Usually the MUA is off, undersized, or has a stuck damper.

Do you clean hoods?

No. Grease-duct and hood cleaning is done by a hood-cleaning contractor. We handle the mechanical systems: exhaust fans, make-up air, interlocks, and balancing.

Can you make the make-up air warmer in winter?

If you have a tempered (gas-fired) MUA, yes; we set the discharge temperature and repair the burner if it is locking out. If you have an untempered unit, we can discuss adding tempering or redirecting the discharge.

Is my make-up air unit required to be interlocked with the hood?

Yes. Mechanical code requires make-up air to operate whenever the exhaust operates. We repair and install interlocks.

Our rooftop unit contractor says we need a bigger AC. Could it be ventilation?

Very often. A dining room that never reaches setpoint in a restaurant with a large hood is usually a pressure problem. We measure before anyone buys tonnage.

Which brands do you service?

CaptiveAire, Accurex, Greenheck, and other common exhaust fan and MUA manufacturers.

How often should exhaust fans and MUAs be serviced?

Quarterly, matched to your RTU maintenance. Belts, bearings, filters, and burner operation drift faster in a kitchen than anywhere else in the building.