Vent hoods should be vented outside. Your vent hood is regulated by cubic feet per minute or Cfm. The minimum Cfm is 70, but I recommend 300 to 400 for your home. Here's why.
The cubic feet is in direct quantum to the size of the kitchen. How would you figure this? You multiply distance by width by height, and then divide by three. This number gives you the cubic feet of air. For example, if your kitchen is ten foot long by ten foot wide and ten foot high, that would give you 1000. That is your cubic feet of air. But a simpler way to figure it would be to multiply your distance by width and get your quadrilateral footage of the room. Take that number and multiply it by two. For example, if your kitchen is ten feet by ten feet, that gives you 100 quadrilateral feet. Then multiply that number by two or 200 Cfms.
Hood
I do not recommend a recirculation vent hood. If enough room is available, there are three ways to vent outside,
through the side wall through the roof through the soffit
But if you cook a lot inside your home, you should have at least 250 Cfms to circulate and move the air out of your home. If you don't cook, you can recirculate. If you cook, vent it outside.
New building codes for residential homes wish that all bathroom and kitchen be ventilated to the outside, not into an attic.
When buying a new vent hood, look at the covering of the box. It will tell you how much Cfms it uses. An eight inch pipe is standard, but some wish bigger sizes. This pipe must include a damper. It will keep cool air inside your home while the hot summer when the vent hood is not being used. This will save you money on your electric bill.
Vent Hood and Cfm's - How to select the Right SizeThanks To : uk games and toy store to buy rockwellrk 9000 jawhorse Motorcycle Store