Kitchen vent fan options to control cooking odors
Dick Reznik
| Posted in Energy Efficiency and Durability on
I’m building a 2200 sq ft ranch with six inch thick combo foam/blown fiberglass walls,triple pane windows and HRV. I would like to avoid the additional exterior wall penetration and cold air infiltration when a traditional kitchen exhaust fan is operating. I was leaning towards a Broan QS1 series recirculating fan to difuse kitchen cooking odors (onions and garlic..no grease). My wife, the cook, says outdoor venting would be best. I’m more concerned with cold air infiltration when the fan is not in operation. My gratitude for any insights or suggestions. Sincerely, Dick
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Replies
Dick,
Two points:
1. There is no doubt that when you duct a range hood fan to the outdoors -- a measure which is required by most building codes -- you have to penetrate the thermal envelope of your home, and you introduce the likelihood of increased air leakage into your home.
2. There is also no doubt that an exhaust fan ducted to the outdoors does a better job of removing cooking odors than a recirculating fan (which, as I pointed out earlier, may not be legal anyway).
Most homeowners conclude that the small thermal penalty associated with a range hood fan ducted to the outdoors is justified.
Many Passivhaus builders, on the other hand, side with you. They prefer to install a recirculating fan (often one that directs the exhaust air flow through a charcoal filter). They also usually install an exhaust grille in the kitchen ceiling, far from the stove. This exhaust grille is connected to a duct that leads to the exhaust side of an HRV. (You need to keep the exhaust grille far from the stove so that you don't gum up the HRV core with grease.)
More info on these issues here: Makeup Air for Range Hoods.
I can't remember who said it best, but "Installing a recirculating fan in a kitchen is like installing a recirculating toilet in a bathroom." Nice picture, eh?
If the range is propane or natural gas, you should absolutely vent outside.
Martin: Thank you for the clarification , especially regarding Passivhaus builders. The installation hints are extremely helpful.
Armando: Certainly a striking visual image.
Kevin: The current plan is to eliminate/reduce combustion gases by using an electric cooktop.
Thank you all for the responsive & timely feedback. Very much appreciated.