The cabinet above the cooker held baking trays. I had never wondered where the hood's duct went until a contractor asked to see it. There wasn't one. Our hood pulled air through filters and returned it through openings near the top.
That explained why replacing the charcoal filter had changed the smell without making the kitchen window stop misting during a long cooking session.
Filtering and exhaust have different jobs
Source: Health Canada: ventilation and the indoor environment
A recirculating hood returns air to the room. Its grease and odour filters do not provide the moisture removal or outdoor air exchange of a ducted exhaust system. Health Canada's ventilation guidance distinguishes that recirculation from ventilation.
The hood manual is the right starting point: some models support either arrangement, and their appearance does not prove which one was installed. We checked the model and asked a contractor to confirm the route rather than dismantling cabinets ourselves.
I kept up the specified filter care. Discovering a limitation was not a reason to run the existing hood with dirty or missing filters.
Plan the route before buying the hood
Health Canada recommends an outdoor-vented range hood for cooking. Converting our kitchen meant discussing an exterior route, suitable ductwork, termination and replacement air, plus permissions where applicable. It was more than ordering a new appliance.
I asked for those items to appear in the proposal. If the route proved impractical, I wanted the limitations explained and a plan for the home's overall ventilation.
We also discussed the cooking we actually do, the noise we would tolerate and access for cleaning. Those details helped narrow the choice.
The old hood had not secretly become an exhaust fan because it sounded busy. Knowing where its air returned let us make a sensible improvement plan and stop expecting a charcoal filter to remove a potful of water vapour.
