A stove without a vent is like a small indoor campfire-but not nearly as romantic. Effective venting removes smoke, grease, odors and steam as you cook. Your walls, cabinets and every other surface in the kitchen stay cleaner, and your lungs breathe easier. Downlights in the hood will also serve an important task-lighting function while you cook.

Some people are turned off by the noise vent hoods produce. To reduce noise, get a variable speed blower and run it only as fast as needed to do the job. An exterior-mounted blower is even quieter, provided there are at least 10 feet of duct between the hood and blower. You'll find that centrifugal blowers (squirrel cage style) are quieter than blade fans. Look for a model rated at 8 sones (the standard measure of fan noise) or fewer.

The key to the vent hood is its venting capacity, which is measured in cubic feet per minute (CFM). As a rule of thumb, you need 2 CFM for each square foot of kitchen floor area. If you do a lot of stovetop cooking, look for a fan with at least 250 CFM.

Overlong ducts and crossdrafts can impair venting. So try to place the cooking and venting against an outside wall, or consult with a professional before installing one elsewhere.

• Ductless Hoods
  The least expensive-and least effective-hood installations are not vented to the outside. The big saving is that you don't have to install a duct. However, ductless hoods don't eliminate all smoke and odors and they don't reduce heat. Instead, ductless hoods re-circulate the room air though a removable filter. If you go this route, it's important to know that charcoal filters remove odors far better than fiberglass filters. Be sure to clean and change filters regularly for best results.
  
  When you purchase a low-cost ductless hood, you'll probably get a 30-in. wide, painted metal or chrome box that mounts under an upper cabinet. They are likely to have fiberglass filters and a 200 - 400 CFM rating. Mid-priced, also 30-in. wide, may be available with a stainless steel box, and feature halogen lights, a quieter fan and charcoal filters. The best of these ductless units come 30-in. wide and larger, with flared custom shapes in stainless, copper, wood or tile. They're quieter, with a 600 CFM fan and charcoal filters.
  
  
• Ducted Hoods
  A vented hood removes smoke, odors and heat from the kitchen through a duct running to the outside. Set above the cooking surface, it catches heat and smoke on the rise and prevents them from polluting your kitchen. Vent hoods, though an essential part of the cooking process, can serve as a visual centerpiece in your kitchen. A wide range of materials and designs gives you plenty to choose from.
  
  Lower-priced 30-in. wide models will feature painted metal or brushed chrome boxes that mount under the cabinet and have a 200 - 400 CFM rating. Mid-priced hoods, also 30-in. wide, may feature a stainless steel box, with baffle filtering (better for smoke), halogen lights and a quieter fan rated at 350 - 600 CFM. If you shop in the higher price range, expect to find 36-in. wide or larger, flared custom shapes in stainless, copper, wood or tile. They'll have exterior mounted blowers and 600-1400 CFM fans.
  
  

Adding a Duct

If you don't yet have a duct to the outside from your new range or cooktop, the cost will vary with the route.

• Try to place the cooktop and hood on an outside wall to minimize the ducting.
  
  
• No matter what the route, try to reduce the number of fittings needed that change the duct's direction, shape or area. These all slow airflow and increase the noise. As the length and intricacy of the duct route increases, you have to increase the fan's CFM, too.
  
  
• Ideally, the hood or exterior vent cover should have an effective damper to stop airflow when the fan is not operating.
  
  
• Never terminate the vent in an attic. In cold weather, the warm air condenses and encourages wood decay.
  
  
• An exterior mounted fan is typically quieter than one mounted in the hood.
  

Hood with Microwave

This space-saving combination incorporates a small hood under a microwave oven. The microwave is installed at about eye-level above the cooking surface (watch the available clearance below the installed combo unit). The unit has either a fixed, flared hood or a slide-out, thin profile vent. On slide-out models the fan starts when you open the hood. These combined units have relatively small hoods that sacrifice some venting effectiveness and should never be used to vent a commercial style range. They're available only in 30-in. width.

With the smallest investment, expect a black or white finish on a re-circulating blower with 230 CFM. In the medium budget range you can afford a stainless steel finish and re-circulating blower. At the high end expect a 300 CFM blower, vented to outside, and combination electric convection and microwave cooking.