Downdraft Ventilation

This is the technology that frees up kitchen design more than anything else.

Downdraft ventilation is a great addition to any kitchen and cooking range or cooktop, be it electric, gas or dual-fuel because of the health benefits of better indoor air quality. It is usually installed in the back of the cooking surface and consist of a powerful exhaust fan and venting system. It may come with sophisticated features like a retractor mechanism, variable speed controls and service alarms.

It's not very well known that cooking vapors add more toxicity to indoor air than any other activity in the home. Specially when high-temperature cooking like stir frying and indoor grilling is common in a home, the contribution of the kitchen to air quality needs to be controlled as efficiently as possible for health reasons. Unfortunately, downdraft systems are simply not as efficient as updraft systems in cleaning the air because while the former need to vent air downwards, against the natural tendency of the smoke and grease fumes to rise, the latter works with this natural tendency and more easily vents away rising aerosol contaminants from overhead hoods. This is more the case when the aerosol grease and steam is rising from tall cooking vessels.

However, we can help downdraft systems to work as efficiently as possible by cooking the more smoke and grease producing foods closer to the downdraft vents and filter which are usually towards the back of the cooktop. We can also:

Buy more powerful units: High CFM (cubic feed per minute) units rated at 500 CFM or greater will work better than less powerful fan ducts that are rated 150 CFM or less. By avoiding the cheaper and less powerful units, we can clean more of our cooking pollution.

Choose the right filters: Filters that can be cleaned in dishwashers easily will tend to be cleaned regularly and therefore remove more contaminants from kitchen smoke. There are also filters available that have an alarm system that notifies us when it is time to clean them. Again, these will cost a little more but repay us many times over with cleaner air to breathe.

Install more efficient ducting: This is unfortunately not always followed in practice and is one of the least costly and most efficient methods of cleaning kitchen contaminants from the air. While designing the ducting system, the contractor or builder should be encouraged to examine the most efficient layouts rather than simply the most easily installed. Often, this is simply a matter of reducing the number of sharp bends in the ducting and replacing them with gradual curves or less-sharp bends. This not only keeps the ducting cleaner by retarding the buildup of grime and grease in the bends but also makes it easier for the fan to vent away more of the contaminated air.

The top downdraft venting system manufacturers are Broan, Bosch, Dacor, Electrolux, Frigidaire, GE, Kitchenaid, Thermador, Viking & Whirlpool.

Thermador makes a model that is very tall, rising 14 inches with full-face filters and recirculation. Dacor makes several raised filters too and also has several remote blower installation options.

Here is one of the best current downdraft ventilation units:

Broan 273603 36" Downdraft Ventilation system w/500 CFM Internal Blower (Stainless Steel)

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This is from the Broan-NuTone Collection and comes with a stainless steel cover as standard and optional colors white, Bisque or black. It is a compact design that is installed unobtrusively behind virtually any self-contained cooktop. It automatically rises into position with the push of a button and retracts completely out of sight, flush with the surface. It also has an easy to use speed control system. Most importantly, it has a front access panel that allows for easy cleaning of the filter.