If you notice that smoke comes from the chimney or stove into the house when you turn on the kitchen hood, it means that a negative pressure issue is being created. This phenomenon is common in well-insulated homes with modern windows and doors, where the hood, by extracting indoor air, creates a suction effect that can reverse the chimney’s airflow and bring smoke back inside.

In this article, we’ll examine the causes of this issue and explore the best solutions to avoid it. Keep reading to better understand how to handle the situation effectively.

Why Does the Chimney Release Smoke When You Turn On the Kitchen Hood?

The connection between the extractor hood and the chimney is directly related to air pressure inside the home. Let’s take a look at the main causes that lead to smoke problems:

  • Air pressure imbalance: In very well-insulated homes, the hood extracts air, but if there’s insufficient air exchange, it creates a vacuum effect that pulls smoke back into the house from the chimney or stove.

  • Improper ventilation system: If there are no dedicated air intakes, the hood may create a "vacuum" effect when it draws too much air, pulling it in from any available opening – including the chimney.

  • Poor chimney draftA flue that is too short, blocked, or has an unsuitable diameter may be unable to counter the negative pressure caused by a particularly powerful hood.

  • House structure: In some cases, renovations and the installation of new windows have eliminated natural air exchange, promoting smoke backflow. This often happens when windows are present but cannot be kept open – for example, during the winter.

These are the most common causes of smoke entering the house when the hood is in use, but don’t worry – below, we’ll look at all the solutions you can adopt in these situations. Let’s go.

Smoke enters through the kitchen hood

Solutions to Prevent Smoke from the Chimney When the Kitchen Hood Is On

Below you'll find three of the most effective solutions to help resolve your problem. You can choose the one that best suits your needs and offers the right balance for addressing the issue:

A) Ensure Proper Air Exchange

  • Install dedicated air vents: Create ventilation holes or install air grilles or ducts that allow air to enter from outside and compensate for the air extracted by the hood.

  • Open a window while the hood is running: A temporary but effective solution to rebalance the air pressure.

  • Consider a mechanical ventilation system (MVHR): An MVHR unit helps maintain a constant balance between incoming and outgoing air.

B) Optimize Chimney Draft

  • Extend the chimney flue: Increasing the chimney height improves its ability to draw out smoke.

  • Install a windproof chimney cap: This helps stabilize draft and prevent smoke from coming back into the house.

  • Clean the chimney regularly: Soot and debris can reduce draft efficiency and increase the risk of smoke backflow.

C) Choose a Hood with the Right Motor

  • Opt for a hood with lower power or variable speed settings: Reducing suction power can help prevent pressure imbalances.

  • Consider a recirculating (filtering) hood instead of a ducted one: Filtering hoods recycle air rather than expelling it outdoors, avoiding the issue of negative pressure.

  • Install an air compensation valve: This system automatically balances internal pressure when the hood is running.

Still having the same problems even after trying these solutions? It might be time to contact a professional.

When to Call a Technician

If the issue persists despite the measures you’ve taken, it’s important to consult an experienced technician for a more detailed assessment and targeted intervention.

A specialist is also needed if the chimney has structural issues or if you want to install a mechanical ventilation system.

And if reading this article made you realize that you’ve never done thorough maintenance on your hood, now might be the right time to do it — by cleaning or replacing the filters. This will help your hood function better and maintain peak efficiency.

At Filtro Cappa, you’ll find everything you need to get your hood back in shape, including brand-new filters and spare parts that will allow your hood to extract and filter air perfectly.
Contact us for expert technical advice, and we’ll help you identify exactly what you need.