Last winter, Megan noticed something odd—her furnace seemed to be running almost nonstop. At first, she chalked it up to the cold snap sweeping through her small Midwestern town. But even on milder days, the constant hum of her HVAC system didn’t let up. She checked the thermostat, changed the filter, and even had her furnace serviced. Still, the problem persisted.

The surprising culprit? Her brand-new, high-powered kitchen vent hood.

If you’ve ever faced a similar issue or are simply curious about the role kitchen ventilation plays in your home’s HVAC balance, you’re in the right place. Let’s unpack how something as innocent as a cooking vent can throw your entire system off-balance—and what you can do about it.

The Heart of the Home: Kitchens and Ventilation

Kitchens are where the magic happens—sizzling pans, steamy pots, and fragrant spices. But all that cooking produces heat, moisture, smoke, and odors. That’s where your kitchen vent hood comes in. Its job is to remove airborne contaminants and push them outside or through a filtration system.

But here’s what many homeowners don’t realize: Vent hoods don’t just suck out air—they also disrupt your HVAC system if they’re not balanced properly.

What a Vent Hood Really Does

A vent hood (or range hood) pulls air from your kitchen and either:

• Sends it outside via ductwork (called an exhaust hood), or

• Filters and recirculates it back into the room (ductless hood).

The stronger the hood’s fan, the more air it removes. High-end models can extract up to 1,200 CFM (cubic feet per minute). That’s a lot of air to replace—and your HVAC system notices.

How Vent Hoods Impact HVAC Balance

Let’s go back to Megan’s home. Her vent hood was rated at 1,000 CFM. That means every minute, it pulled 1,000 cubic feet of conditioned air out of her house.

Now imagine that air isn’t being replaced. What happens?

1. Negative Pressure Builds Up: Your home becomes like a vacuum. Air gets sucked in from wherever it can—through cracks, poorly sealed windows, even from the attic or garage.

2. Cold Air Rushes In: Especially in winter, this leads to cold drafts, which your furnace tries to counteract—constantly.

3. Furnace Runs Continuously: It’s working overtime to maintain your desired temperature because your home is leaking air faster than it can warm it.

4. Indoor Air Quality Declines: Instead of fresh, filtered air, you’re pulling in dusty, allergen-laden air from unconditioned spaces.

How to Avoid the “Overworking Furnace” Trap

Luckily, there are solutions that can restore balance and keep your HVAC system from working harder than it should.

1. Proper Hood Sizing

Choosing the right size hood is step one.

• Electric cooktops: Aim for 100 CFM for every 10 inches of cooktop width.

• Gas ranges: Need more—100 CFM for every 10,000 BTUs.

• Island hoods: Add 100 CFM for open-air exposure.

📌 Rule of Thumb: Most standard kitchens do fine with 250–600 CFM unless you’re cooking commercially or with high-BTU gas ranges.

2. Makeup Air Systems

This is the magic fix Megan didn’t know she needed.

A makeup air system brings fresh, conditioned air back into your home to replace what the hood removes. These systems prevent negative pressure and help your furnace maintain a stable workload.

Some models are even tied into the HVAC system and heat the makeup air before distributing it—talk about efficiency!

3. Use Your Hood Wisely

• Turn on the hood only when cooking.

• Use lower fan speeds when possible.

• Seal other parts of your home—doors, windows, and attic spaces—to reduce unwanted air infiltration.

When to Call in a Pro

If your furnace runs constantly and you suspect it’s tied to ventilation, call an HVAC professional who understands whole-home airflow dynamics. They can:

• Perform pressure tests

• Evaluate your current HVAC and hood setup

• Recommend or install makeup air systems

They’ll ensure your comfort, energy bills, and air quality aren’t being compromised by your kitchen habits.

Conclusion: Balance Is the Key

What seemed like a minor home upgrade—installing a high-powered kitchen vent hood—turned into a cascade of HVAC headaches for Megan. But with a few adjustments, including the addition of a makeup air system and dialing down the hood’s fan speed, her furnace finally caught a break.

Your kitchen might be the heart of the home, but your HVAC system is the lungs. Treat them both with care, and your whole house will breathe easier.

FAQs About Vent Hoods & HVAC Balance

1. Why does my furnace keep running even when it’s warm inside?

A common cause is air imbalance. If your vent hood is pulling air out but not being replaced, your furnace will keep running to maintain the set temperature.

2. What is a makeup air system?

It’s a ventilation device that introduces fresh air into your home to replace what’s removed by exhaust systems like range hoods. It keeps pressure balanced.

3. Can a kitchen vent hood really affect my HVAC system that much?

Yes—especially high-CFM models. Without proper compensation, they can create negative pressure, making your HVAC system work harder.

4. How do I know what size vent hood I need?

Match your hood’s CFM to your cooktop type and size. For electric, 100 CFM per 10” of width. For gas, factor in BTUs. Islands need extra CFM.

5. Is it better to use a ductless range hood?

Ductless hoods are easier to install and don’t impact HVAC as much, but they’re less effective at removing moisture and odors compared to ducted models.

6. Should I run my vent hood all the time?

No. Use it only when cooking, especially during high-heat or high-moisture processes like frying or boiling.