Make-up Air Systems in Sunnyvale: Balanced Airflow That Passes Inspection

Signs Your Exhaust System Needs Make-up Air

You notice it before you can name it. The back door to the kitchen suddenly takes a shoulder to open. Your exhaust hood used to clear fryer smoke in seconds, but now the smoke lingers. Something’s off: too much air is leaving the building, and not enough is coming back in.

• Exterior doors that slam shut on their own or take real muscle to pull open
• A kitchen exhaust hood that struggles to clear smoke, steam, or grease vapor
• Whistling or hissing around windows and door frames
• Pilot lights on water heaters or furnaces that flicker, or a burner that won’t stay lit
• A faint burnt or gas smell near appliances that vent through the roof
• Rooms that feel stuffy or oddly cold near exhaust fans, even with the HVAC running fine

Any one of these signs on its own might be nothing. Two or three together form a pattern, especially when a kitchen hood or large exhaust fan runs most of the day. Negative pressure does more than make a building uncomfortable. It can pull exhaust gases back down flue pipes that should carry them outside.

That last problem worries us most. Backdrafting isn’t just about comfort. It’s a safety issue, so we don’t treat these symptoms as minor.

Tempered vs. Untempered Make-up Air: Matching the System to North Texas Weather

Untempered make-up air pulls outside air straight into the building. It doesn’t heat or cool the replacement air. That works fine in mild weather, but Sunnyvale doesn’t stay mild for long.

Summer here can mean pulling 100-degree air through a kitchen hood system for months. An untempered unit dumps that heat into your dining room or walk-in cooler‘s mechanical space. Your main HVAC system then fights the added heat all day. We’ve seen restaurant owners chase comfort complaints for weeks before tracing them back to unconditioned make-up air.

Tempered systems heat or cool incoming air before it enters your building. They require more equipment and cost more upfront, but they put less strain on everything downstream. Summer highs and winter cold fronts can both hit North Texas hard. In those conditions, tempered make-up air often earns its keep fast.

Which one is right for your building? It depends on how you use the space and how often the exhaust runs. The rest of your mechanical setup also matters. A commercial kitchen running hoods twelve hours a day has different needs than a warehouse with occasional exhaust fans. We size the system around your usage, not a one-size-fits-all spec sheet.

Not sure which category your building falls into? That’s a normal question. Most owners aren’t expected to know this off the top of their head.

When a Dedicated Make-up Air Unit Isn’t Required

Not every exhaust fan or range hood needs a dedicated make-up air unit. We’ll tell you that directly, even when it means less work for us.

A single restroom exhaust fan moves a small amount of air, and so does a basic range hood in a break room. If the exhaust is modest and the envelope is not tightly sealed, ordinary infiltration through gaps around doors, windows, and penetrations may supply enough replacement air on its own. We see that in older Sunnyvale buildings still on original construction, where the envelope simply leaks enough to keep the space from going negative.

Newer, tightly sealed subdivisions are a different story, but that alone doesn’t mean you need a unit. What matters is the exhaust volume compared with the fresh air your space gets naturally.

• A single bathroom exhaust fan running on a normal switch, not a continuous system
• A standard kitchen range hood pulling a modest, everyday amount of air
• A dryer vent by itself, since dryers don’t usually trigger make-up air requirements on their own
• Older buildings with enough natural infiltration through the envelope to balance the exhaust
• Rooms where the exhaust fan rarely runs, such as a seldom-used guest bathroom

If your setup falls into one of those groups, you likely don’t need us out there for make-up air. The fix may be as simple as cleaning a dirty exhaust fan. It could also mean adjusting the hood’s fan speed or checking for a blocked vent. We’d rather tell you that on the phone than send someone out for nothing.

What to Expect During a Make-up Air Installation

You’ve decided a make-up air unit is the right fix. Here’s what installation day looks like, with no mystery involved.

Our team arrives with your building’s exhaust load already calculated. We complete that math before touching a tool, so the work follows a clear plan instead of guesswork.

• Confirm where the new unit connects to your existing ductwork or roof curbs.
• Set and secure the unit on the roof or wall, based on your building.
• Connect the ductwork and wire the unit to interlock with your exhaust hood or fan.
• Start the system and test the balance between exhaust and incoming air.
• Check gas venting and combustion safety if the unit is gas-fired.
• Walk you through the controls before we leave.

The balance test in step four matters more than many people realize. We’ve entered Sunnyvale kitchens where the exhaust hood ran full blast. Staff had to prop open the back door just to breathe. A properly balanced make-up air system fixes that problem without anyone touching a door.

Startup and testing aren’t a formality; they’re the point of the job. We check the temperature rise and confirm the unit starts with the exhaust fan. We also make sure your space stays properly pressurized instead of fighting itself.

Most installations wrap up in one visit. Our licensed and insured technicians haul away old equipment when there is any. We also explain what we did, so you aren’t left guessing about changes to your building.

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Passing Final Inspection with a Tested Interlock

Some contractors rush this part. Installing the make-up air unit isn’t enough. It also has to work with the exhaust system connected to it.

That proof comes down to the interlock. Many commercial kitchens, walk-in coolers, and exhaust-heavy spaces in Sunnyvale use fans that pull air out fast. The make-up air unit must start automatically when that exhaust turns on. Without the interlock, you don’t have balanced airflow. That’s one of the first things an inspector checks.

• Confirm the exhaust fan and make-up air unit are electrically interlocked, not merely installed side by side
• Run the exhaust system and watch the make-up air unit respond within seconds
• Check airflow with a balancing tool so the space isn’t starved for air or overpressurized
• Verify that dampers open fully and close tightly when the system shuts off
• Inspect the ductwork for leaks or restrictions that could throw off the readings

We test the interlock before calling the job done, not after the inspector arrives. That prevents a scramble, rescheduling, or another day with your kitchen shut down.

A failed interlock test often traces back to rushed wiring. It can also come from pairing the exhaust with an incorrectly sized unit. We see both problems more often than you might expect.

Once the interlock passes and the airflow readings hold steady, your system stops fighting the building and your energy bill. That’s the point of installing it correctly.