The Kitchen That Couldn’t Stay Cool

A few summers ago, the Thompsons moved into their newly built home in Ottawa. It had everything—modern finishes, open concept living, and a high-end gas range with a commercial-grade vent hood. Yet every summer, they noticed the kitchen and adjoining living space became unbearably warm during meal prep.

Even with the AC blasting at 22°C (72°F), it felt like someone had turned on a sauna. The culprit? An oversized vent hood that was pulling more than just cooking fumes—it was throwing their entire HVAC system off balance.

How Range Hoods Impact HVAC Balance

Range hoods are essential for removing smoke, grease, steam, and cooking odors. But a powerful vent hood doesn’t just extract air—it displaces it. In homes without balanced make-up air systems, this air must come from somewhere. If your kitchen hood is removing 600 CFM (cubic feet per minute) or more, it could create negative air pressure in the house.

Here’s what that means for your HVAC system:

• Air Pressure Imbalance: The HVAC system struggles to maintain consistent airflow, especially in open-plan homes.

• Backdrafting Risks: In gas appliance homes, negative pressure can draw combustion gases back into the living space—a serious safety concern.

• Reduced AC Efficiency: Warm outside air can be sucked into the home through cracks and gaps, making your AC work overtime.

Proper Ventilation: The Unsung Hero of Summer Comfort

Good kitchen ventilation isn’t just about removing smoke—it’s about managing air circulation so your HVAC system doesn’t have to fight a losing battle. Here’s how to get it right:

1. Use a Make-Up Air System

If your vent hood exceeds 400 CFM, Canadian building codes often require a mechanical make-up air system. This system replaces the air being exhausted with fresh, tempered air.

2. Vent Outside, Not Into the Attic

Always direct your vent hood outside the home—not into the attic or wall cavity. This prevents heat and humidity from accumulating where it shouldn’t.

3. Balance Is Everything

Ventilation systems should be properly balanced with your home’s HVAC system. Work with an HVAC professional to ensure your setup doesn’t create pressure imbalances.

Sizing Guidelines for Kitchen Vent Hoods

When it comes to choosing the right vent hood, size and power matter—but more isn’t always better.

A. Match CFM to Cooking Needs

Here’s a quick cheat sheet based on cooktop type:

B. Width Matters

Your hood should be at least as wide as your cooktop. For best results, go 3 inches wider on each side. For example, a 30″ stove works best with a 36″ hood.

C. Mounting Height

The standard height between cooktop and vent hood is:

• Electric ranges: 20–24 inches

• Gas ranges: 24–30 inches

This allows for proper suction while minimizing loss of conditioned air.

What AC Temperature Is Best in Canadian Summers?

Now that your kitchen isn’t sabotaging your HVAC system, you can actually enjoy a cool, efficient summer. Most experts recommend setting your AC between:

• 23–25°C (73–77°F) for comfort and energy savings.

• Increase slightly during the night or when you’re away to reduce costs.

If you’re using ceiling fans or dehumidifiers, you can keep the thermostat a bit higher and still stay comfortable.

Conclusion: Cooking Smart Means Cooling Smart

The next time you wonder why your kitchen feels like a steam room while your AC runs nonstop, take a closer look at your range hood. With the right ventilation setup, balanced airflow, and appropriate hood sizing, you can reclaim your kitchen comfort—and your energy budget.

The secret to summer comfort in Canada isn’t just about the thermostat. It’s about designing your kitchen and HVAC system to work in harmony.

FAQ: Kitchen Ventilation and HVAC in Summer

1. How do vent hoods affect HVAC systems?
Powerful vent hoods can disrupt airflow by creating negative pressure, making your HVAC work harder to maintain indoor temperature.

2. What is make-up air and why do I need it?
Make-up air replaces the air exhausted by your vent hood. It keeps pressure balanced and ensures efficient HVAC performance.

3. How do I know if my range hood is too powerful?
If it’s over 400 CFM and you don’t have make-up air installed, you may experience pressure imbalance and energy inefficiency.

4. Should I leave my vent hood running after cooking?
Yes, for 10–15 minutes to clear remaining pollutants. Just ensure you’re not overcooling or overheating your home in the process.

5. Can a vent hood be vented into the attic?
No. Always vent outside. Attic venting can cause mold, structural damage, and poor air quality.

6. Does a recirculating hood affect HVAC?
Recirculating hoods don’t expel air, so they have less HVAC impact but don’t remove heat or humidity effectively.

7. How do I calculate the right hood size for my kitchen?
Match hood width to your range and CFM to your cooking intensity. A professional can also assess your home’s airflow needs.

8. What’s the ideal summer AC temperature in Canada?
Aim for 23–25°C (73–77°F) for a good balance of comfort and energy efficiency.