How far can you vent a range hood? Your range hood duct should not exceed 30' for a straight run, 25' for a run with one elbow, and 20' for a run with two elbows. The shorter the duct, the better. If your ductwork is too long, your kitchen air may not reach the outside.
Following the 3-inch rule, your range hood should not be more than three inches wider on the left and three inches on the right, or 6 inches wider in total than your kitchen range.
Although the international CFM code for range hoods is 100CFM, some local authorities allow for range hoods with slightly lower or higher CFM than this, depending on the type of your cooking, and the square footage of your cooktop.
In general, yes an exhaust vent (or any vent) can turn corners.
No, you should never vent your range hood into the attic. The excess buildup of grease and moisture in your attic will ruin it and over time may cause mold damage. Instead, vent your hood through an interior wall or through the ceiling all the way outside of your home.
Range hoods do not have to be vented to the outside. You can purchase hoods without ductwork called ductless hoods. But, ducted range hoods are almost always preferred over ductless hoods.
Although it is a desirable option, a regular kitchen cooktop does not need to be vented and exhausted to the outside. A downdraft cooktop and grill must be vented from the kitchen to the outside, following manufacturer's specifications.
To power your range hood, you need at least 100 CFM for every 10,000 BTUs of your stovetop. For example, a 100,000 BTU stove needs at least a 1000 CFM range hood. For electric stoves, multiply the stove width by 10. So, for a 42” electric stove you want a range hood with at least 420 CFM.
An exhaust fan is required in a kitchen. A kitchen exhaust fan removes particles, smoke, carcinogens, and odors from your kitchen's air. They prevent your house from filling up with cooking smoke and setting off alarms. Many local residential building codes require them.
Unvented range hoods do filter some grease and cooking odors from the air, but the general consensus is that they're nowhere near as effective. Nor do they remove heat and humidity, so they won't help keep your kitchen cool while you cook.
You must not vent into the soffits, or even under the soffits unless you are more than a foot and a half below the soffit to allow the wind to dissipate the moisture before it rises back up into the attic.
There's no great way to vent your range hood, but you need to ensure that you have sufficient space behind walls to run the ductwork before proceeding with the installation. Also, it's a great practice to decrease some elbows in the ductwork. This maximizes the efficiency of airflow, making a path of least resistance.
Most range hood manufacturers recommend mounting your range hood between 20 and 24 inches above your kitchen range, but we recommend at least 28 inches for our professional-quality, powerful vent hoods.
For example, if you have a 30” range, a 36” wall mounted range hood (3” longer than the range on each side) is the perfect size. It will vent unwanted contaminants out of your kitchen with incredible efficiency.
In general, most installations require a distance from 20" to 24" between the bottom of the hood and the cooking surface. Over a gas range, this distance should be between 24" and 30", unless otherwise specified.
If you have a gas range, install your range hood 24 to 36 inches above your cooktop. If you have an electric range, install your range hood 20 to 24 inches above your cooktop. If you have an outdoor grill, install your range hood 36 to 42 inches above your cooktop.
What size range hood do I need for a 30” cooktop? With a 30” range, a 36 inch range hood is your best choice.
For high-output gas ranges or cooktops, the minimum rate of 1 CFM of ventilation per 100 British thermal units (BTU) is recommended. For example, if your high-output burner output is 45,000 BTU, look for a range hood that provides 450 CFM to best clear the air. However, the higher the CFM, the louder the hood will be.
Limited Effectiveness
Because of their design, downdraft vents work harder than updraft systems to remove air, and are usually ineffective at drawing steam, odors and smoke from burners that are farthest away, and from tall stockpots.
With D49M Series, the groundbreaking new downdraft from BEST, you can design confidently, knowing it will pair with a broad range of cooktop appliances—aesthetically and mechanically—in virtually any installation configuration.
If your stove is near an exterior wall, the fastest way is to go through the wall. Other vents have to go up through the roof. If your home has a chimney, you can often connect the vent pipe to the chimney instead of creating another hole in an exterior wall.
Cost to Vent Range Hood Outside
The cost of installing the ductwork needed to vent a range hood outside is about $500, depending on the labor it requires and the cost of the new ductwork.
A ductless (or ventless) range hood does not vent out of the home, instead, it carries the debris and smoke form the air and filters it through a charcoal or carbon filter before releasing it back into the room. While many times this method is not as functional as a vented hood, it does work.
Rigid duct is the best type of duct to vent your range hood. It requires a one-time installation and little to no maintenance as long as you clean your range hood filters. Most rigid ductwork is made from durable stainless steel, as opposed to rigid ductwork which is aluminum or flimsy plastic.