KitchenAid Sunken Cooktop with Pop Up Vent Hood

Regardless of the type of stove you have–either gas, electric, or induction—you need to have some type of built in kitchen ventilation system. Many areas even require them by law. Kitchen ventilation removes excess moisture, heat, smoke, cooking odors, and chemical byproducts due to fuel combustion from the house so as to make the kitchen environment clean, healthy and comfortable. Furthermore, up to one gallon of grease goes into the air from cooking every single year! Without some form of ventilation system of filter, all that grease eventually condenses and attaches itself to furniture, walls, windows, and curtains! For providing ventilation in the kitchen, chimneys and oven hoods are the most common appliances used. They work to remove cooking fumes by utilizing an extraction fan to either filter the air, or exhaust it outside. We put together a list of some of the basic things you need to know when shopping for a new kitchen ventilation system so that you can breath easy.

There are two basic types of configurations for kitchen ventilation systems, vented or ducted, and non-vented or duct free, as well as a few units with combinations and variations on the theme. Here are some of the pros and cons of each type of kitchen ventilation system:

Vented Oven Hoods
Ducted or vented oven hoods are the most efficient and popular type of ventilation system by which fumes are exhausted outdoors using a duct or channel. The kitchen exhaust fan must have an outlet to the outdoors, using smooth ducting with as few bends as possible. Too long a duct might require a larger fan or insulation to prevent moisture condensation. It is therefore best to place the stove alongside an exterior wall, allowing for direct outlet to the outdoors. Standard ducts are either 6 inches wide in diameter or 3 1/4 x 10 inches for rectangular models although the more powerful the system, the larger the vent, with some ducts as large as 10 inches in diameter. Most units also come with grease filters to catch the oil preventing it from attaching to walls and curtains. It is important to note that it is essential to purchase a properly sized fan for your vented oven hood to avoid the risk of depressurization, in which deadly fumes are sucked back into the house. (Read “Power” below for more information)

Duct Free Oven Hoods
Whereas vented oven hoods transport the kitchen fumes out of the house, non-vented or duct-free systems filter the air using washable and replaceable filters and then return it to the kitchen through vents at head level. Although they pull steam and smoke away from the stovetop, removing odors and fumes by way of a charcoal filter, they don’t prevent heat and moisture caused by steam. Recirculating kitchen exhaust fans are therefore not recommended for anyone who can install a vented system. They are however ideal for kitchens that are built on inside walls of the house. Filters need to be replaced at least once a year but replacements are on the expensive side, so people often neglect to change them regularly enough, greatly diminishing their effectiveness. On the positive side, there’s no concern of depressurization with duct free oven hoods since they don’t attach to the outside.

Convertible Ventilation Systems
Convertible ventilation systems can be used with or without ducts depending on where you have them installed. They basically make it easier for stores, so they only have to carry one model and are beneficial for consumers since they can be converted if you move houses and find it necessary to switch from a ducted system to a non-ducted one or visa-versa.

Combination Systems
Combination kitchen ventilation systems combine an oven hood with a microwave oven which are both mounted above the stovetop.

KitchenAid Canopy Ventilation Hood

Power
Not all hoods can be used efficiently on both gas and electric ranges. Each range requires its own CFM (cubic feet per minute), which is essentially a measurement for how powerful the exhaust system can pull air. An electric range requires less CFM than a gas range and therefore a range hood anywhere between 220-300 CFM is more than adequate. The proper CFM for a gas range will depend on the gas range’s BTU. For every 100 BTUs you need around 1 CFM from your oven hood. Therefore a gas range with 450,000 BTU’s requires a range hood of about 450 CFMs. If the oven hood is installed on an interior wall or island, the distance to the outside will be longer and therefore a higher CFM will be necessary to successfully remove the air. Professional ranges require more powerful ventilation systems with up to 1400 CFMs.

Too large a fan will detract too much air from your house—if your home is heated or air conditioned, that’s expensive air that you’ve paid for. It will also cost more in utility bills to run. More importantly, an oversized fan can cause depressurization which leads to back-drafting, pulling deadly combustion gasses from furnace exhaust back into the house. A qualified professional should be contacted to check your HVAC (Heating, Ventilation and Air Conditioning) system and the kitchen exhaust, and install a CO alarm in your home to make sure that everything is functioning safely.

Fan Placement
There are basically three types of fan locations for kitchen ventilation systems: internal fans placed inside the oven hood, remote mount blowers which consist of an external fan, and in-line blowers where the fan rests inside the ductwork. Internal fans are the most basic and do a fine job for normal ranges. Remote fans are more powerful and since the fan is located outside the house, it is somewhat quieter. Nonetheless, the majority of noise comes from the air getting sucked through the ducts, so don’t be fooled when testing out a fan inside the store–it will be substantially louder when it is fully installed in your house. They are however preferred in conjunction with a professionally sized range. In-line blowers are more powerful and are best when air has to pass through a long system of ducts to reach the outside.

Size
The length of the hood should be according to the range size, and it should be as wide as the range. This will also protect cabinetry from heat and smoke damage. It should be mounted at a proper height so that the exhaust fumes are sucked up before they have a chance to disperse into the kitchen. A standard oven hood is 6 inches high, although professional ranges may require hoods as large as 18 inches tall.

Styles
There are basically three different styles of oven hoods: chimney styles, under cabinets, and hood liners. Chimney styles hang directly under the ceiling whereas under-cabinets rest underneath the upper kitchen cabinetry, as the name suggests. Both are generally built of stainless steel and may be painted. Hood liners, on the other hand, require special built-in cabinets that hide the hood inside, so that they don’t become the focal point of the kitchen décor.

Additional Features to Consider:

• Hoods are made up of fans which are either rotary (like a traditional bladed fan) or centrifugal (barrel shaped). A centrifugal fan will move more air, more quickly, and is quieter to operate and is therefore the more popular option.
• Hoods come with automatic shutoff features in which the fan is automatically switched off after a specific preset time. Some turn on automatically throughout the day to ensure that air stays fresh in the house without getting stale.
• Heat sensors automatically activate fans or speed up fan oscillation, and some even sound an alarm when they detect increased heat.
• Lighting options are also available on hoods with one or two incandescent. More expensive items come with up to four halogen bulbs.

Keeping your kitchen air safe and clean is a priority! We hope that this guide has been helpful to assist you in purchasing the right kitchen ventilation system for your needs. Remember, fresh air is our greatest commodity!