kitchen ventilation: what are CFMs?

Minnesota homes, like others in colder climates, are built air-tight. It’s not really something we think about until we remodel our kitchens.

Oh yes. That beautiful, pro-style range or cooktop. All that power. All those BTUs. But all those BTUs require a certain amount of another acronym: CFMs.

More heat being produced means more heat needing to be exhausted. But our state code actually says ventilation hoods can’t exceed 300 Cubic Feet per Minute before needing “makeup air.”

Why? It’s kind of confusing, honestly, but Faber Rangehoods has a good explanation on this:

A situation of negative pressure could also occur when too much air is pulled out of the home and it is not replaced by air from the outside. In today’s construction the homes are becoming more and more air tight and when too much air is pulled out of a home, you need to sometimes “make up” for that lost air by pumping outside air into the home

Before you get really excited about the solution of makeup air, understand that depending on your home, it will cost $2,000 to $10,000.

Passive makeup air, which is less expensive, could work for the 300-600 CFM range. Passive makeup air is basically holes in your house that only bring air in or out depending on air pressure differences.

The safest bet in Minnesota? Unless you want to invest a boat load of money, stick to a 300 CFM hood. This limits you to about 3,000 BTUs of cooking power (using our 100 CFMs per 1,000 BTUs suggestion), but erring on the safe side also protects the investment you make in your kitchen.

For instance, think about what all that extra smoke, grease and moisture will do to your cabinets. Plus, your house could end up smelling like a Burger King. Is that really what you wanted?

If you’re still not satisfied with that answer, you might be able to cheat a bit by oversizing the vent (i.e. 3 inches of overhang on both sides). This will increase the capture area of your smoke and grease.

Sticking to 300 CFMs gives you fewer options, for sure, but they’re nothing to snub. Previously mentioned Faber makes a 250 CFM insert hood liner. Broan makes an affordable 300 CFM hood.

But if you’re looking to top your pro-style vent with something higher-end, check out Vent-A-Hood. They’re quiet and they come with full, five-year warranties.